Whisper and Phonation: Aerodynamic Comparisons Across Adduction And

Home , Glottis, Whispering

WHISPER AND PHONATION: AERODYNAMIC COMPARISONS

ACROSS ADDUCTION AND LOUDNESS LEVELS

Ramya Mohan Konnai

A Dissertation

Submitted to the Graduate College of Bowling Green

State University in partial fulfillment of

the requirements for the degree of

DOCTOR OF PHILOSOPHY

May 2012

Committee:

Ronald C. Scherer, Advisor

Lewis Fulcher Graduate Faculty Representative

Roger Colcord

Alexander Goberman

Ramya Konnai

Ronald Scherer, Advisor

ABSTRACT

The purpose of the present project was to compare the aerodynamics of whisper and phonation. The novel aspect was to have subjects produce both whisper and phonation for nine different conditions, three qualities relative to levels of adduction (breathy, normal, and pressed) and three levels of loudness (soft, medium, and loud). The study reports subglottal pressure (Ps),

airflow (F), and laryngeal flow resistance (Rf, the ratio Ps/F) for all conditions. Three males and

five females between 20 and 30 years of age whispered and phonated smooth syllable strings of

/baep/. This resulted in 18 treatment combinations (i.e., 3 adductions x 3 loudness levels x 2

genders). A regression analysis was performed using a Proc-mixed procedure with SAS

statistical software.

Results relative to laryngeal source (phonation vs. whisper): Ps was not significantly different between whisper and phonation (except for the breathy soft condition in females, where

Ps was greater in phonation). Flow typically was higher for whisper than phonation (except for

soft conditions, where flow was about the same). Rf tended to be greater for phonation than for

whisper for females, but not for males (where Rf was about the same between phonation and

whisper).

Results relative to loudness: Ps increased with loudness (soft, medium, loud) at each of

the three adduction levels for both phonation and whisper. Flow tended to increase with loudness

in whisper at each level of adduction, but flow results were varied for phonation. In phonation,

Rf increased with loudness at each level of adduction, but there was no general pattern for

whisper (being relatively constant across loudness levels for each gender). iv

Results relative to adduction: Ps increased from normal to breathy to pressed at each level of loudness for phonation, and similarly for whisper (except Ps was about the same for normal and breathy whisper productions). Breathy adduction had the greatest flow at each level of loudness for both phonation and whisper. Flow was about the same in both phonation and whisper for normal and pressed productions. Rf increased from breathy to normal to pressed at each level of loudness (although for whisper, Rf was similar for breathy and normal productions)

Results relative to gender: Ps tended to be higher in males than females for all nine conditions for phonation and whisper. Males tended to have greater flow for phonation but lower flow for whisper for all conditions. Males produced greater Rf values for whisper across adduction, but lower Rf values (relatively small differences, however) for phonation across adduction levels.

While there are some clear and understandable trends for the aerodynamic measures relative to changes in loudness and adduction for whisper, phonation, and gender, the results are best taken as testable hypotheses for future research.

This dissertation is dedicated to:

The memory of my beloved grandfather,

M. Elumalai.

You encouraged me to pursue my dreams.

My husband, Asai.

You make my dreams come true! vi

ACKNOWLEDGEMENTS

This project would not have been possible without the guidance of Dr. Scherer, my advisor. Dr. Scherer, you took a genuine interest in my learning and challenged me in my academic program. I will always remember our lengthy brainstorming discussions (not necessarily all the content), the long hours spent making figures on excel, and above all our ability to laugh away even at the eleventh hour of meeting a deadline. You taught me not just about the larynx but lessons for life. Thank you!

Sincere thanks to my committee members- Dr. Goberman, Dr. Colcord, and Dr. Fulcher for their time and input on my project. I am grateful to Amy Peplinski and Dr. Kenneth Ryan from the Statistical Consulting Center, BGSU for their immense help with the data analysis. A big “Thank you” to Jason Whitfield for assisting me with data collection. Special thanks to Dr.

Fari Alipour, University of Iowa, for providing solutions with technology issues in the lab whenever we needed. Thanks also go to Dr. Hewitt for supporting my transition from University of Cincinnati and helping me throughout my program at BGSU. I am thankful to the College of

Health Sciences and the Graduate College, BGSU and University of Cincinnati for the financial support of my education.

I am indebted to my husband, Asai, for being patient, supporting, and encouraging throughout this tough and long journey. Special thanks to my son, Aarya, for bringing absolute joy into my life and constantly reminding me to enjoy the simple moments every day! I cannot thank my brother and parents enough for all their care and support throughout my life. Thanks to my cohorts- Haidee Tan, Biji Philip, Emily Rusnak, Scott Palasik, Eric Swartz, Farzan Irani,

Charlie Hughes, and Stephanie Hughes for lending their ears day and night and helping me to get to the end of this program. Friends, Sabiha Parveen, Purnima Gopalakrishnan, Siva “akka,” vii

Sethu Karthikeyan, and Vijay Ramachandra deserve special thanks for accommodating my needs at Bowling Green when I needed it the most. Thanks also go to friends from Cincinnati, Venkat,

Prodipto, Ritesh, Renuka, Anu “didi”, Rohit, and Chris for making me feel at home when I was

10,000 miles away from home. Last but not the least, thanks to Dr. Alice Silbergleit, Henry Ford

Health System for her encouraging comments and being flexible with my work schedule.

viii

TABLE OF CONTENTS

Page

CHAPTER 1. INTRODUCTION…………………………………………………………1

1.1 Phonation types ...... 1

1.2 Whisper vs. phonation...... 3

1.3 Significance of whisper ...... 3

1.4 Loudness and intensity ...... 5

1.5 Aerodynamics ...... 6

1.6 Whisper characteristics ...... 9

1.7 Proposed research ...... 13

CHAPTER 2. METHODOLOGY ...... 14

2.1 Subjects ...... 14

2.2 Equipment ...... 14

2.3 Syllables for analysis ...... 15

2.4 Procedure ...... 15

2.5 Data analysis ...... 20

2.6 Significance ...... 22

CHAPTER 3. RESULTS ...... 23

3.1 Research question 1 ...... 30

3.2 Within-subject and between-subjects variability ...... 42

3.3 Research question 2 ...... 44

3.4 Research question 3 ...... 55

3.5 Values for variables ...... 65 ix

CHAPTER 4. DISCUSSION ...... 66

4.1 Subglottal pressure ...... 66

4.2 Airflow ...... 69

4.3 Flow resistance ...... 72

4.4 Other observations ...... 74

CHAPTER 5. SUMMARY ...... 75

CHAPTER 6. CONCLUSION ...... 90

REFERENCES ...... 95

APPENDIX I. Table of physical characteristics of subjects...... 105

APPENDIX II. Flow mask and oral pressure calibrations ...... 106

APPENDIX III. Figures of pressure vs. flow for each subject ...... 113

APPENDIX IV. Consent form...... 133

LIST OF TABLES

Table Page

1 Proc Mixed Model Terms for Log Subglottal Pressure (Ps)...... 28

2 Proc Mixed Model Terms for Log Laryngeal Airflow ...... 29

3 Proc Mixed Model Terms for Log Flow Resistance ...... 29

4 Summary of Predicted Subglottal Pressure ...... 31

5 Predicted Values and 95% Confidence Intervals for Mean Log Ps

and Median Ps by Treatment Based on Table 1 Mode ...... 33

6 Summary of Predicted Laryngeal Airflow Values...... 35

7 Predicted Values and 95% Confidence Intervals for Mean Log Flow and

8 Median Glottal Flow by Treatment Based on Table 2 Model ...... 36

9 Terms with Significant Difference in Airflow between Whisper and

Phonation ...... 37

10 Summary of Predicted Flow Resistance values ...... 38

11 Predicted Values and 95% Confidence Intervals for Mean Log Resistance

and Median Flow Resistance by Treatment Based on the Table 3

Model ...... 39

12 Terms with Significant Differences between the Flow Resistance

of Whisper and Phonation ...... 40

13 Predicted Median Subglottal Pressure (Ps), Airflows (Fl), and Flow

Resistances (R) across Loudness in Males (M) and Females (F) ...... 45

14 Predicted Median Subglottal Pressure (Ps), Airflows (Fl), and Flow

Resistances (R) across Adduction in Males (M) and Females (F)...... 56 xi

LIST OF FIGURES

Figure Page

1 Residual Analysis from Full Model of Subglottal Pressure...... 24

2 Residual Analysis from Full Model of Laryngeal Airflow ...... 25

3 Residual Analysis from Full Model of Flow Resistance ...... 25

4 Residual Analysis from Full Model of Log Subglottal Pressure ...... 27

5 Residual Analysis from Full Model of Log Laryngeal Airflow ...... 27

6 Residual Analysis from Full Model of Log Flow Resistance ...... 28

7 Predicted Subglottal Pressure from Table 1 Model ...... 30

8 Predicted Laryngeal Airflow from the Table 2 Model ...... 34

9 Predicted Laryngeal Airflow from the Table 2 Mode ...... 38

10 Sample Medians of Subglottal Pressure by Treatment ...... 41

11 Sample Medians of Laryngeal Airflow by Treatment ...... 41

12 Sample Medians of Flow Resistance by Treatment ...... ……………………42

13 Pressure vs. Flow Relationship across Loudness in Pressed Whisper ...... 46

14 Pressure vs. Flow Relationship across Loudness in Pressed Phonation ...... 46

15 Pressure vs. Flow Relationship across Loudness in Breathy Whisper...... 49

16 Pressure vs. Flow Relationship across Loudness in Breathy Whisper...... 49

17 Pressure vs. Flow Relationship across Loudness in Normal Whisper ...... 50

18 Pressure vs. Flow relationship across Loudness in Normal Phonation ...... 50

19 Pressure vs. Flow Resistance across Loudness in Pressed Whisper ...... 52

20 Pressure vs. Flow Resistance across Loudness in Pressed Phonation ...... 52

21 Pressure vs. Flow Resistance across Loudness in Breathy Whisper ...... 53 xii

Figure Page

22 Pressure vs. Flow Resistance across Loudness in Breathy Phonation ...... 53

23 Pressure vs. Flow Resistance across Loudness in Normal Whisper ...... 54

24 Pressure vs. Flow Resistance across Loudness in Normal Phonation ...... 54

25 Pressure vs. Flow Relationship across Adduction in Soft Whisper ...... 58

26 Pressure vs. Flow Relationship across Adduction in Soft Phonation ...... 58

27 Pressure vs. Flow Relationship across Adduction in Medium Whisper ...... 59

28 Pressure vs. Flow Relationship across Adduction in Medium Phonation ...... 59

29 Pressure vs. Flow Relationship across Adduction in Loud Whisper ...... 60

30 Pressure vs. Flow Relationship across Adduction in Loud Phonation ...... 60

31 Pressure vs. Flow Resistance across Adduction in Soft Whisper ...... 61

32 Pressure vs. Flow Resistance across Adduction in Soft Phonation ...... 61

33 Pressure vs. Flow Resistance across Adduction in Medium Whisper ...... 63

34 Pressure vs. Flow Resistance across Adduction in Medium Phonation...... 63

35 Pressure vs. Flow Resistance across Adduction in Loud Whisper ...... 64

36 Pressure vs. Flow Resistance across Adduction in Loud Phonation ...... 64

CHAPTER 1.

INTRODUCTION

Laryngeal sound sources have been discussed as the absence of voicing (i.e., as in whisper and aspiration), to breathy voice, to regular modal register voicing, to vocal fry, and to full glottal closure (Alku & Vilkman, 1996; Ladefoged, 1971). This range has been suggested based on the aperture between the arytenoid cartilages, or in other words, glottal adduction.

People can control the glottis so that they can produce speech sounds with not only regular voicing vibrations at different pitches but also using harsh, creaky, breathy, and a variety of other phonation “types” (Gordon & Ladefoged, 2001), often referred to as voice qualities

(Childers & Lee, 1991). These phonation variations are controllable relative to the actions of the glottis and not just personal idiosyncratic possibilities or involuntary pathological actions

(Gordon & Ladefoged, 2001). For example, Gordon and Ladefoged (2001) explain that the occurrence of phonetic rarities such as the strident voice quality that occurs in the !Xόõ language and a few other neighboring languages shows that people can use the glottis in a wide variety of ways. In order to expand our knowledge of differentiating how various laryngeal sound sources are produced, a primary objective of this study was to explore comparisons between two basic and quite different laryngeal sound source types, whisper and phonation.

1.1 Phonation types

In this study, the term “phonation types” of breathy, normal, and pressed voice productions will refer to the (primarily) adductory classification. These types are associated with the position of the vocal folds resulting from the contraction and coordination of the laryngeal adductory and abductory muscles, and thus the arytenoid cartilages (Scherer & Titze, 1986;

Sundberg & Rothenberg, 1987). In reality, there are several degrees of freedom to position the 2 arytenoid cartilages (and therefore also the vocal processes) to achieve a variety of glottal configurations.

The configuration for breathy voice is typically found to be an incomplete closure of the glottis, either the posterior glottis alone or both the anterior and posterior glottis. Breathy voice is characterized by having both modulated flow from vocal fold vibration as well as turbulent noise from flow through the more static open portions of the glottis. Acoustic analysis of breathy voice shows that its acoustic signal is less periodic than non-breathy voice due to the turbulent noise present in the breathy voice (Hillenbrand, Cleveland, & Erickson, 1994). Klatt and Klatt (1990) report that the harmonic components in breathy signals tend to be relatively weak in the high frequency region and aspiration noise is stronger in the mid and high frequencies than in the lows. Clinically, breathy voice is found in patients with vocal fold paralysis, sulcus vocalis, laryngeal trauma, and radiated larynx (Isshiki, Kitajima, Kojima, &

Harita, 1978), as well as in those with glottal obstructions (polyps, etc.) and in patients with functional breathiness (where the glottis is held open without an organic problem present).

Modal voice in the typical speaking F0 range is characterized by very little turbulent noise, regular, quasi-periodic components, and an open quotient that is approximately 50% with an average amount of vocal fold impact stress (Alku & Vilkman, 1996).The fundamental frequency and intensity can be varied from lower to higher values (Kent & Ball, 2000). Modal voice in this study will be called the “normal” voice type.

Pressed phonation is a type in which the vocal processes of the arytenoid cartilages are pressed together resulting in a constricted glottis with relatively low modulated airflow and relatively high medial compression of the vocal fold tissue during the closed portion of the glottal cycle (Fujimura & Hirano, 1995). Pressed voice is considered an etiological factor in 3

phonotraumatic injury due to tight vocal fold adduction and increased vocal fold impact stress

(Grillo & Verdolini, 2008). In terms of glottal flow characteristics, the pressed phonation type

has been suggested as being distinguished from normal phonation by its lower peak flow value,

shorter return time of the differentiated flow, longer closed period, and shorter delay between

peak flow and peak-differentiated flow (Sundberg, Titze, & Scherer, 1993).

1.2 Whisper vs. phonation

Unlike phonation, whisper is an aphonic laryngeal action that is characterized by the

absence of vocal fold vibration (Colton, Casper, & Leonard, 2006). According to Luchsinger

and Arnold (1965), whisper differs from phonation in the following manner: a) The glottis

shows the shape of an inverted Y, and the vocal folds are incompletely closed. b) The vocal fold

tension is much lower than in phonation, and the folds do not vibrate; as a result, the escaping

air is set into non-periodic frictional turbulence so that a noise is produced instead of a tone with

periodic vibrations. c) The expiratory air volume is greatly increased; whispering is therefore

“much more strenuous” than speaking in a normal voice. d) The subglottal air pressure is much

lower than it is during phonation. Hence, according to Luchsinger and Arnold, it is incorrect to

classify whisper as a type of phonation or use the term “whispered voice.”

1.3 Significance of whisper

Whispering is a socially significant form of communication (Cirillo, 2004). Cirillo

(2004) surveyed 350 people to find out when and why people whispered. Fifty-nine percent of the subjects said that they seldom whisper and 24% said that they whisper from time to time.

More than 50% of the subjects mentioned that whispering has a “contagious” effect. Thirty-eight percent of the subjects indicate that they whisper in private, often quite frequently. People whisper in order to a) avoid disturbing someone (for example, in “silence zones” of libraries and 4

hospitals), b) communicate a secret message to a specific person and confirm affiliation with the

person, c) initiate a playful encounter or for fun, and d) attract the attention or induce curiosity in

members of an audience (Cirillo, 2004). Actors and singers use “stage whisper” for special

effects (Poyatos, 2002), and children whisper during play. Patients with aphonia communicate by

whispering (Luchsinger & Arnold, 1965). Furthermore, “soft whisper” is therapeutically

prescribed for some patients with vocal pathologies (Hufnagle & Hufnagle, 1983). This unique

physiologic action of the larynx (whispering) is important to the understanding of certain

pathological vocal phenomena, such as aphonia and vocal fold paralysis. Also, in the field of

communication, the rare occurrence of a specific signal is often correlated with high relevance

and there is evidence that a rare usage can help to sustain a signal’s salience (Todt 1986, in

Cirillo, 2004). Hence, whisper can be used as a rare alternative to phonation for communication effect.

Differences in whisper and phonation types imply important linguistic information in many languages (Gordon & Ladefoged, 2001), are identified in vocal pathologies (Kent & Ball,

2000), used to communicate mood, emotion, and attitude (Gobl & Chasaide, 2002), and are also used in vocal performance such as singing and in dramatic speech (Poyatos, 2002). Hence, investigating different ways of producing both whisper and phonation constitutes an important

area of research as such an investigation is relevant to theories, models, and synthesis of

laryngeal sound sources and communication styles and intents, and to clinical diagnosis and

intervention.

1.4 Loudness and intensity

Loudness is a common perceptual characteristic of laryngeal sound production (Childers

& Lee, 1991). Loudness is defined as that attribute of auditory sensation that corresponds most closely to the physical measure of sound intensity (Plack & Carlyon, 1995). Varying loudness is

an important aspect of communication effectiveness. Various professionals such as speech

language pathologists, singing teachers, voice and speech coaches, and instructors of public

speaking, attempt to modify loudness to enhance speaking and singing skill (Schmidt, Gelfer, &

Andrews, 1990). It is not surprising that researchers in a number of fields have been concerned

with loudness perception and physical measures of vocal intensity, and the variability of these

factors. For example, considerable research has studied underlying mechanisms to “vocal”

intensity relative to physiological measures such as aerodynamics, acoustics, and

electroglottography (Dromey, Stathopoulous, & Sapienza, 1992; Grillo & Verdolini, 2008;

Holmberg, Hillman, & Perkell, 1988; Holmberg, Hillman, Perkell, Guiod, & Goldman, 1995;

Mendoza, Valencia, Munoz, & Trujilo, 1996; Stathopoulous, 1986; Stathopoulous & Sapienza,

1993; Tanaka & Gould, 1983). Intensity changes have also been studied as a function of

elicitation task and music training (Schmidt, Gelfer, & Andrews, 1990), and as a result of certain

pathologies.

Titze (1994) explains that changes in vocal intensity are brought about by three distinct

mechanisms at three anatomic levels at, below, and above the larynx. At the level of the larynx,

intensity changes can be made by making adjustments to the glottal width (the distance between the

vocal folds and between the arytenoid cartilages). Below the larynx, intensity can be regulated by

the aerodynamic power supplied by the lungs to the vocal system. Above the larynx, vocal intensity

can be varied by adjusting formants and how well they coincide with harmonics of the source. Titze 6

also mentions that not all three mechanisms are routinely used by speakers. Clinical studies have

suggested that quiet whisper may be used when vocal rest or minimal voice usage is recommended

as part of treatment and does not impede vocal fold tissue healing following surgery for vocal fold

lesions such as nodules (Colton, Casper, & Leonard, 2006; Hufnagle & Hufnagle, 1983). However,

an operational definition of quiet or loud whisper is unavailable in the literature. Colton, Casper,

and Leonard (2006) point out that by contrasting whisper and habitual loudness in phonation,

speech language pathologists may help improve awareness in patients who habitually use excessive

loudness and make it easier for them to accomplish the target loudness level. A study of the

production of quiet, medium, and loud whisper that identifies the changes in aerodynamic and

acoustic measures is needed as a backdrop for recommendations of the appropriate use of whisper

loudness for patients with vocal fold lesions.

A large number of acoustic, aerodynamic, and articulatory measures potentially

distinguish the different types of phonation and whisper (Grillo & Verdolini, 2008). Some of these measures include periodicity, intensity, spectral tilt, fundamental frequency, formant frequencies, and airflow (Kent & Ball, 2000). In this proposal we are interested in using selected aerodynamic measures (mean flow, mean subglottal pressure, and glottal flow resistance) to investigate the differences among whisper and phonation variations, with a special emphasis on whisper.

1.5 Aerodynamics

Aerodynamics provides information related to the valving characteristics of the glottis

during phonation (Ladefoged, Maddieson, & Jackson, 1988) and whisper as well as to

respiratory capacity, as given by measurements for air pressures, airflow, and air volume

(Sapienza & Dutka, 1996). 7

Subglottal pressure (Ps) is the amount of pressure exerted on the inferior surfaces of the vocal folds and can be measured in cm of H2O (or more currently, kPa). It is the primary factor for raising vocal intensity (Baken & Orlikoff, 2000). Direct measures of Ps are determined through invasive procedures such as tracheal puncture or an airway catheter (Baken & Orlikoff,

2000). Indirect measures are estimated from measures of the intraoral air pressure during the production of a plosive, such as /p/ produced in the sequence /pVpVpVp/, where “V” is a vowel.

In producing the /p/ phoneme, the vocal folds are abducted sufficiently to stop vocal fold oscillation and the lips and velopharyngeal port are closed, sealing the airway. Within a short time after bilabial closure, the pressure within the oral cavity reaches the value equal to the Ps.

If the /pv/ sequence is performed smoothly, the Ps value that existed during the production of the previous and next vowel when the vocal folds were adducted will be equal to the oral pressure during the /p/. Abnormalities in Ps can be indications of impedance in the vocal tract, neuromuscular abnormalities of the chest wall, and pulmonary disease (Baken & Orlikoff, 2000).

Mean Glottal airflow: The mean airflow over the course of producing a speech sound, phonation, or an utterance may be of value when assessing the general characteristics of speech and vocal function. According to Hirano (1981), the normal mean phonatory airflow rate is between 90 and 140 mL/s, although a given speaker’s airflow may range between approximately

70 and 200 mL/s when voice is maintained at comfortable pitch and loudness. Glottal airflow has also been shown to be an apparent determinant of vocal intensity (Tanaka & Gould, 1983).

However, the relationship between glottal airflow, vocal intensity, and fundamental frequency is complex. Increases in Ps result in greater sound pressure but not necessarily in greater flow. At high fundamental frequencies, however, flow does increase with increasing vocal intensity and

Ps (Isshiki, 1965). Some other factors that may influence flow measurements include the 8 instructions and feedback provided to the speaker before and during the task (McCurrach, Evans,

Smith, Gordon, & Cooke, 1991; Soman, 1997), voice onset characteristics (Koike, Hirano, &

Von Leden, 1967; Beckett, 1971; Murry & Schmitke, 1975), and whether the data are derived from phonation sustained over a comfortable or maximal duration (Terasawa, Hibi, & Hirano,

1987). Average airflow is most useful and reliable as an indicator of relatively large changes in vocal function; for example, comparing vocal function before and after medialization for vocal fold paralysis (Hillman & Kobler, 2000).

Glottal flow resistance is defined as the ratio of mean subglottal pressure divided by mean glottal airflow (Hirano, 1981). It apparently is a major controlling parameter of vocal intensity for low pitched phonation and in the modal register according to Ishikki (1964). To increase glottal flow resistance for a constant subglottal pressure, the adductory muscle system of the larynx that positions the vocal folds to the midline must contract more. Such increased muscle activity would also lead to an increase in the subglottal pressure to sustain vocal fold vibration near threshold (Aronson & Bless, 2009). Low glottal flow resistance may be seen in cases of glottal incompetence and high flow resistance may be seen in cases of reduced tissue pliability and hyperfunction (Aronson & Bless, 2009).

The airflow and pressure measurements are of great assistance in diagnosis, documenting change during therapy, and providing biofeedback to patients with pathologies of voice or articulation (Amerman & Williams, 1979; Dalston, Warren, & Dalston, 1991; Fritzell,

Hammargerg, Gauffin, Karlson, & Sundberg, 1986; Gordon, Morton, & Simpson, 1978; Leeper,

Gagne, Parnes, & Vidas, 1993; Miller & Daniloff, 1993; Rammage, Pepard, & Bless, 1992;

Ruscello, Shuster, & Sandwisch, 1991; Tanaka, Hirano, & Terasawa, 1991; Warren, 1996;

Watson & Alfonso, 1991; Woo, Colton, & Shangold, 1987). Yiu, Yuen, Whitehill, and 9

Winkworth (2004) found that the aerodynamic measures of mean flow and estimated mean subglottal pressure could be used to reliably predict the voice condition (non-dysphonic vs dysphonic) with an accuracy rate as high as 91% when five trials were included for each measure.

1.6 Whisper characteristics

Whisper is characterized by the presence of turbulent noise (Colton, Casper, & Leonard,

2006). According to Schwartz (1970), whisper has a flat spectrum and a marked reduction in intensity especially between 125 and 4,000 Hz when compared to phonation. Traunmuller and

Ericksson (2000) found that in whispering, speakers adopt an articulation that is similar to phonation produced at a higher vocal effort. This may be caused by a need to increase the vocal fold tension in order to prevent vocal fold vibration. The authors assert that when controlling vocal effort, such as an increase in vocal fold tension, a modification of articulation is possible.

Speakers may also modify their articulation in an attempt to increase the audibility of their whisper in the same way as they may do for phonation (Traunmuller & Ericksson, 2000). The glottal area during the production of whispered or aspirated vowels is in the range of 0.1 to 0.5 cm2 and instantaneous airflow rates can be as high as 1500 cm3/s (Stevens, 1971). Stathopoulos,

Hoit, Hixon, Watson, and Solomon (1991) found that their subjects (ten normal adults) generally terminated breath groups at lower values of lung volumes, ribcage volumes, and abdominal volumes, used fewer syllables per breath, and expended more air per syllable during whispering than phonated speaking. They found that whisper had lower tracheal pressure, higher peak flow, and higher average flow than phonated speaking. Weismer and Longstreth (1980) found that the mean intraoral pressure differences between the whispered /p/ and /b/ were similar to the /p/-/b/ pressure differences in phonation. The peak flow difference for /p/ and /b/ 10

in whisper was reduced when compared to corresponding differences in phonation. In whisper,

the peak flow of /p/ (mean= 388 cc/s; SD= 141 cc/s) was greater than the peak flow of /b/

(mean= 276 cc/s; SD= 126 cc/s). However, this finding was when repetition of syllables was the task. When the stimulus was a carrier phrase (Say /p/ again; Say /b/ again), the peak flow of whispered /b/ was greater than /p/. The difference between mean intraoral pressures of /p/ and

/b/ were not significantly different in whisper but was significantly different in phonation.

Similar results were found by Murry and Brown (1976). In an attempt to find out if glottal flow

resistance played a role in the pressure differences of the stop cognates, the authors did a slope

analysis of the intra-oral pressure data. They assumed that since the rate at which the pressure

develops in the closed vocal tract is dependent on the magnitude of the glottal flow, greater

slopes for intraoral pressure should indicate greater flows and thus less glottal flow resistance.

Slope data were calculated from the initial linear portion of the pressure data (intraoral pressure

signals have an initial linear portion, a brief plateau, and peak pressure) for the stop cognates in

phonation and whisper. The pressure slopes (expressed in cm H2O/centisecond) for voiceless

stops were greater (and hence reflecting less glottal flow resistance) than voiced stops in both

phonation and whisper. The absolute difference in intraoral pressure slopes between /p/ and /b/

was greater for normal phonation than in whisper. This suggests that the difference in glottal

flow resistance for whispered /p/ and /b/ brings about changes in the peak flow but the

difference may not be large enough as in phonation to produce a difference in intra-oral pressures. The authors concluded that the segmental gestures in phonation were preserved to some extent in whisper due to the peak flow differences and the intraoral pressure slopes between /p/ and /b/. 11

To our knowledge only two studies have reported the aerodynamic measures of whisper

at different loudness levels. Monoson and Zemlin (1984) compared two types of whisper (quiet

and loud or forced whisper) with breathy and normal phonation in five young adult females. In

their group of female subjects, mean flow was the greatest for forced whisper (328 ml/s)

followed by breathy phonation (258 ml/s), quiet whisper (203 ml/s), and normal phonation (120

ml/s). These mean airflow values for whisper are much lower than the mean airflow values (0.9-

1.71 L/s) found by Sundberg, Scherer, Hess, and Müller (2010). This difference could be due to

the nature of the subjects used in the studies. The Monoson and Zemlin study investigated young

adult female subjects, whereas Sundberg et al. investigated an older adult male. Age and gender

effects have been found for mean glottal airflow with elderly males demonstrating significantly

greater airflow rates compared to young females (Holmberg et al., 1988; Higgins & Saxman,

1991; Isshiki & Von Leden, 1964; Koike & Hirano, 1968; Netsell et al., 1991; Yanagihara et al.,

1966). Also, the Monoson and Zemlin study did not use other routine aerodynamic measures

such as estimated subglottal pressure or glottal flow resistance. Glottal flow resistance especially

has been shown to distinguish normal, breathy, and pressed phonation (Grillo & Verdolini,

2008).

Sundberg et al. (2010) examined aerodynamic and glottal measures for different levels

of loudness and adduction in whisper. A tall male was the subject for this study. The subject

produced four types of whisper: hyperfunctional, neutral, hypofunctional, and post-phonatory, at

three loudness levels (soft, medium, and loud). Measurements were made of the glottal area,

glottal flow, and subglottal pressure. For this subject, whisper had a wide range of subglottal

2 pressures: 1.3 - 17 cm H20; glottal flow: 0.9 - 1.71 L/s; glottal area: 0.065 - 1.76 cm ; and glottal perimeter: 1.09 - 1.76 cm2. Hyperfunctional whisper tended to have higher subglottal pressures 12 and lower areas and flows than hypofunctional whisper, with neutral and postphonation whisper values in between. In hypofunctional and hyperfunctional whisper, the glottis assumed a rectangular or elliptical shape for this subject. Prior investigations of glottal configuration during whisper revealed vocal folds with straight edges or a toed-in configuration (Solomon, McCall,

Trosset, Gray, 1989). The authors found that glottal flow changed more for small changes of area when the area was already small than when it was already large. The authors derived an equation for whisper aerodynamics (relating glottal flow, subglottal pressure, and glottal area), as well as an equation involving nondimensional terms (pressure coefficient and Reynolds number relative to glottal perimeter divided by glottal area).

While the study by Sundberg et al. is the first of its kind to offer generalized expressions for whisper aeromechanics, the limited subject sampling of the study (the study used a single subject) does not provide insights into individual differences. Whisper especially is known to be produced by different speakers differently. Research by Hicks and Sweat (1983), Solomon et al.

(1989), Rubin et al. (2006), and Fleischer, Kothe, and Hess (2007) suggest that there is high inter- and intra-subject variation during whisper production, especially with respect to glottal configuration that influences glottal aerodynamics. At the level of the glottis, individuals demonstrate various configurations such as no vocal fold contact, various degrees of closeness of the two vocal folds, and compression of the anterior and middle thirds or the entire length of the true vocal folds. At the level of the supraglottis, there may be various degrees of false vocal fold gap and/or anterior-posterior displacement of the epiglottis and arytenoid cartilages. In general, these variations in laryngeal configuration lead to variability of pertinent measures of whisper.

Thus, establishing the extent to which the chosen measures vary across and within individuals is crucial for the clinical use of these measures. It is noted that wide variability does not imply lack 13 of order among the production variables of whisper, but that individuals may differ in their productions of whisper when given the same instructions. Also using subjects who differ in gender would help determine whether or not gender should be taken into account in the evaluation and management of people with voice disorders when whisper is considered.

1.7 Proposed research

The present study attempts to answer the research questions below:

1. Do subglottal pressure, flow, and flow resistance differ between phonation and whisper

relative to loudness and adduction in males and females?

2. Do subglottal pressure, flow, and flow resistance vary across the three loudness levels

(soft, medium, and loud) for phonation and for whisper in males and females?

3. Do subglottal pressure, flow, and flow resistance vary across the three adduction levels

(breathy, normal, and pressed) for phonation and for whisper in males and females?

The results of using this level of specificity should help to clarify the aerodynamic characteristics of each production condition and contribute to an understanding of the variability of whisper measures. Also, a comparison of aerodynamic measures using different levels of loudness and adduction in whisper is relevant to voice and whisper diagnostics and therapy. For example, the treatment goal for patients with aphonia and vocal fold paralysis may progress from their use of whisper to the production of breathy phonation and ultimately normal phonation.

Knowledge of aerodynamic measures at different levels of adduction and loudness in both whisper and phonation can assist in better understanding whisper production and in the objective assessment and determination of progress in therapy.

CHAPTER 2

METHODOLOGY

2.1 Subjects

Eight subjects (3 males and 5 females) participated in the study. The subjects’ ages were in the range of 20 to 30 years. The mean age for male subjects was 22.6 years (SD = 3) and the mean age for female subjects was 23.8 years (SD = 2.8). All subjects were non-smokers and native speakers of English with no history of voice or speech problems, hearing loss, or professional voice training. The study was advertised across the BGSU campus using flyers and emails. Subject characteristics are included in Appendix I. Normal pitch was verified by measuring the fundamental frequency from the normal adduction – medium loudness conditions.

2.2 Equipment

A Glottal Enterprises aerodynamic flow mask system (MSIF-2 S/N 2049S) was used to obtain oral air pressure and airflow. Static calibrations for pressure and flow were completed

(See appendix II for details). A head band microphone system (AKG C-420, AKG acoustics,

Austria) with pre-amplifier (APHEX 107, APHEX systems, Sun Valley, CA) was used to record acoustic signals simultaneously with the airflow recordings. The mouth to microphone distance was held constant at 6 cm for all subjects. Headband microphones have the advantage of being close to the mouth, maximizing the strength of the direct signal in relationship to the background noise (Baken & Orlikoff, 2000). All signals were simultaneously recorded into a 16-bit DATAQ

A/D system (model DI-720 Series, Dataq Instruments, Akron, OH) and analyzed using custom-

written “Sigplot” software using MATLAB.

2.3 Syllables for analysis

Subjects were instructed to produce at least five trials of the five syllable series of /bæp/, i.e., /bæp:bæp:bæp:bæp:bæp:/ smoothly on one breath for each condition of whisper and phonation. However, for certain conditions such as breathy whisper at loud volume, subjects were unable to produce to five syllable series and produced only up to three syllable series. In such instances, subjects produced additional trials to arrive at a sufficient number of syllables for analysis. The middle three syllables within each trial were averaged and used for analysis. There were a total of 721 valid syllables for analysis. Each syllable yielded a single mean subglottal pressure estimate, mean flow, and derived flow resistance.

2.4 Procedure

Screening: Eleven individuals responded to the advertisement and underwent a screening by the experimenter for the target productions of whisper and phonation at different adduction and loudness levels. The subjects passed the screening for target production if the subject was a) able to perceptually discriminate the three types of adduction and the three loudness levels b) produce the three adduction and loudness levels after the experimenter had demonstrated them.

Subjects were also screened by the experimenter for hearing at 500Hz, 1kHz, and 2 kHz at 20 dB. Eight subjects passed the hearing screening and the screening for the target productions, and participated in the study.

Training: The goal of training was to refine the skills of the subjects to differentiate and produce a) phonation and whisper, b) three adduction levels for both phonation and whisper

(breathy, normal, and pressed), c) each of the adduction conditions at each of the three loudness levels of soft, medium, and loud, and d) produce the /bæp:/ sequence very smoothly so that pressure measurements (and thereby flow measurements also) would be valid because tracheal 16

pressure would remain relatively constant throughout. Subjects received visual feedback of the

oral pressure signal by viewing it on an oscilloscopic display during training (with target flat

portions of intraoral pressure during lip occlusion). Training concluded when subjects were able

to correctly produce at least three valid tokens of the voice and whisper types at the different

loudness and adduction conditions. The time taken for training subjects varied from 45 to 75 minutes. Training and recording of the experiment was carried out on the same day.

The experimenter demonstrated and provided verbal descriptions of the different phonation and whisper types. Normal voice was demonstrated and described as a spontaneous voicing mode without any attempts to manipulate the quality of the voice. Breathy voice was demonstrated and described as easy phonation, characterized by auditory air escape during phonation, with the vocal folds abducted and the feeling that more air than usual is exiting the body. Pressed phonation was demonstrated and described as extremely high adduction phonation, with the perception of a completely closed airway at the glottal level and very little air flow. Normal whisper was demonstrated and described as a noise caused by rapidly flowing air through the glottis, in the absence of phonation. Breathy whisper was described and

demonstrated as whisper with unusually high levels of airflow, in the absence of phonation.

Pressed whisper was described and demonstrated as whisper with very little airflow and a

constricted glottis, in the absence of phonation. Although the experimenter demonstrated the

various voice and whisper types, subjects were instructed to produce their own version of the

different voice and whisper types and were coached in their validity or appropriateness relative

to the description of the six sound source types. Pitch was not controlled for the phonation tasks

considering that it was likely to increase with loudness in vocally untrained subjects. 17

Each subject practiced each of the different adduction levels (three for phonation and

three for whisper) at each of the three different levels of loudness (soft, medium, and loud).

Normal/Medium loudness was the subject’s preferred comfortable loudness during a short

dialogue with the experimenter sitting approximately 3 feet away for phonation and whisper.

Loud voice was above the subject’s comfortable loudness level by at least 5 dB, and soft voice was below the subject’s comfortable loudness level by at least 5 dB. Approximate loudness levels were attained by first prolonging /a/ at a comfortable loudness to obtain the corresponding dB value using a B & K (Bruel & Kjaer Type 2230) sound level meter. Then the /bæp:/ sequence near that loudness and effort level was practiced. For the loud level, /a/ again was prolonged at least 5 dB higher than for the comfortable /a/ prolongation. The /bæp:/ sequence was then practiced with that loudness and effort level. Similarly, for the soft productions /a/ was prolonged at least 5 dB less than that for the comfortable condition, followed by practicing the /bæp:/ sequence at that loudness and effort level. Participants were instructed to take a deep enough breath before beginning the /bæp:/ syllable train to produce the entire syllable train on a continuous expiration. Subjects were also instructed to use constant effort throughout all syllable strings and to produce them very smoothly. Breathy productions did not permit a full string of 5 syllables. However, shortening the vowel portion of the syllable, without changing the mean flow, allowed more syllables within the breath group.

Recording: The subjects replicated the same procedures that they practiced during training. The subject was comfortably seated inside a IAC sound-treated booth (4 feet x 6.3 feet x 6.5 feet) in the voice physiology laboratory, Bowling Green State University. One experimenter was present with the subject inside the sound booth. A second experimenter outside the sound booth monitored the signals on a multichannel computer oscilloscope and recorded the 18 signals using Windaq Pro software (Dataq Instruments). The subject placed the mask over his or her face with the thin oral pressure tube positioned between the lips; the tube end was placed in the mouth but was not obstructed by the tongue. The subject was instructed to hold the mask firmly on his or her face during the recording, covering the mouth and nose, ensuring an adequate seal on the skin of the face. The subject also wore the head-band microphone with the microphone located off to the side of the corner of the mouth by 6 cm. The experimenter with the subject monitored the mask fit and seal, mouth-to-mic distance, and the correct production of the tokens during the recording. The mouth to mic distance was periodically checked by measuring the distance using a ruler.

The subject first produced the different phonation conditions followed by the whisper conditions. Within each condition of phonation and whisper, the “normal” adduction condition was produced first at normal loudness followed by soft and then loud. This was followed by the production of the hypoadducted condition at normal, soft, and loud levels. Finally, the hyperadducted condition was produced at normal, soft, and loud levels. Five or more successful trials were recorded for each of the nine conditions (3 levels of adduction and 3 levels of loudness) for phonation and nine similar conditions for whisper. A ten minute interval was given after recordings of phonation were completed. Subjects were asked to repeat any token that they or the experimenters considered as a poor example of the intended condition. Any token considered unacceptable by either the subject or the experimenters was excluded from analysis.

Pilot study: Two young adult female subjects participated in the pilot project a) to determine if the training techniques proposed could be easily followed, and b) to estimate the approximate amount of time for training and collecting data. Pilot subject 1 was a speech- language pathologist with two years of experience and pilot subject 2 was a first year speech- 19 language pathology Master’s student. The subjects were chosen according to the inclusion criteria for participating in the study. Neither subject had any formal speech or singing training.

The findings of the pilot study suggest that the subjects did not have any difficulty with the instructions. When asked for suggestions to improve the instructions, they reported that the wording of the instructions and demonstrations in the present form were clear and easy to follow.

Training Subject 1 took about 20 minutes and she was able to produce all nine conditions (three adduction levels and three loudness levels) for phonation and whisper with ease. She was able to produce five tokens (/baep:baep:baep:baep:baep:/) smoothly for all nine conditions. However, during the training for the production of breathy whisper, the subject tried to contrast the soft, normal, and loud conditions in one breath (a technique not to be used in the experiment) and felt

“a little lightheaded.” She quickly reported feeling fine again after taking a couple of breaths and she felt the need to drink water. Training Subject 2 took about an hour. She was also able to smoothly produce all nine conditions for phonation and whisper. She needed additional training to produce soft pressed condition for both phonation and whisper. She had some difficulty contrasting her “normal” loudness and “soft” loudness especially during the production of pressed phonation and whisper. She was asked to count from 1 to 5, with 1 being the softest and

5 being the loudest. This exercise helped her to contrast the loudness levels. She was able to produce five tokens (/bæp:bæp:bæp:bæp:bæp/) for all nine conditions of phonation. For whisper, she was able to produce five tokens for all the conditions except normal loudness - breathy whisper and loud breathy whisper. She “ran out of air” for the normal loudness – breathy whisper and loud breathy whisper and was able to produce only two tokens for both of those conditions. When she was instructed to shorten the duration of the vowel in /bæp/ she was able to 20

produce 3 tokens for the normal loudness-hypofunctional whisper and loud hypofunctional

whisper.

Once the training was completed, the two subjects produced the nine conditions for whisper and phonation with the face mask as if it were a recording session (the signals were not

recorded). Two experimenters were present and judged if each of the tokens produced were

valid. The subjects produced a single trial of the nine conditions without any interval and it took

less than 10 minutes. Assuming the same time for the reminder of the trials, the total time for

recording five trials would take about 50 minutes. A one minute interval should be sufficient

after each trial which would make the duration 55 minutes. Thus, with these two subjects the

total time that this experiment would take was estimated to be about 2 hours (one hour training and one hour of recording). However, in the real situation we anticipated a little longer time to ensure that the mask would fit, to record the signals with enough time, and to allow that some

subjects may need to have more training and practice. Thus, the experiment was estimated to

take less than two and half hours for each subject.

2.5 Data analysis

The independent variables in the study are source (whisper and phonation), adduction

(three levels), and loudness (three levels). The dependent variables are measures of

aerodynamics (mean Ps, mean airflow, and laryngeal flow resistance). Table 1a below is a check

list and cells for values for each subject.

Chart showing how data were entered for each subject

PHONATION/WHISPER PS PM PL NS NM NL BS BM BL Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Adduction: P (Pressed), N (Normal), B (Breathy) Loudness: S (Soft), M (Medium), L (Loud) Each trial = 5 syllables of /baep/. Middle 3 syllables were averaged and used for analysis.

Each of the microphone, air flow, oral pressure, and sound intensity signal were recorded into a separate channel of the DATAQ A/D converter using a sampling rate of 20,000 Hz per channel. The digitized signals were analyzed using custom software (SIGPLOT). In SIGPLOT, each signal’s baseline was adjusted to be zero. The pressure and flow signals were then averaged. The experimenter chose the points on the pressure and flow signals for analysis and these were not automatically calculated by the software. The software then calculated the average values for pressure, flow, and flow resistance.

The following analyses were made:

Multiple paired comparisons: These will be made between whisper and phonation across the nine conditions using the aerodynamic and SPL measures. Pressure, flow, flow resistance, and SPL depend on larynx size, and differences are expected (e.g., lower flows for females for comparable adduction and Ps values due to having smaller larynxes). Hence, a comparison between males and females will help to investigate if they use similar values and patterns across the nine conditions, for both whisper and phonation.

Regression analysis of variance was used to analyze the data to answer the questions: 22

1. Do Pressure, Flow, and Resistance differ between Phonation and Whisper relative to

Loudness and relative to Adduction in males and females?

2. Do Pressure, Flow, and Resistance vary across the three Loudness levels for Phonation

and for Whisper in males and females?

3. Do Pressure, Flow, and Resistance vary across the three Adduction levels for

Phonation and for Whisper in males and females?

2.6 Significance

The general significance of the present study is to gain a deeper understanding of the production of two laryngeal sound sources used in speech, whisper and phonation, as they contrast relative to adduction and loudness. The results of this laryngeal sound source study should help establish a functional basis for understanding whisper and its relation to phonation, and its inference for clinical use. Estimates of airflow, air pressure, and laryngeal flow resistance during whisper production would also be useful in synthesis of whisper and training of professional voice users to produce stage whisper.

CHAPTER 3

RESULTS

The aim of the present study was to compare whisper and phonation relative to chosen aerodynamic measures. The independent variables were source (whisper and phonation), adduction (pressed, normal, and breathy), and loudness (soft, medium, and loud). The dependent variables included the laryngeal airflow, subglottal pressure, and flow resistance. The research questions that were proposed were

1. Do subglottal pressure, flow, and flow resistance differ between phonation and whisper

relative to Loudness and adduction in males and females?

2. Do subglottal pressure, flow, and flow resistance vary across the three loudness levels

for phonation and whisper in males and females?

3. Do subglottal pressure, flow, and flow resistance vary across the three adduction levels

for phonation and whisper in males and females?

Eight subjects (5 females and 3 males) participated in the study. Each subject produced each of the treatment combination (i.e., three levels of adduction and three levels of loudness) at least five times (i.e., five trials). The five trials resulted in variability of the subjects’ productions within each of the treatment combinations. Another objective of this study was to study the within subject variability and between subject variability in the production of whisper and phonation.

The main and interaction effects along with the subject variability were analyzed through regression analyses by using the PROC MIXED procedure in the SAS statistical program. The

PROC MIXED procedure is a mixed linear model where the data are permitted to exhibit correlation and non-constant variability. The mixed linear model provides the flexibility of modeling not only the means of the data (as in the standard linear model) but also their variances 24

and covariances. PROC MIXED fits the structure one selects to the data using the method of restricted maximum likelihood (REML), also known as residual maximum likelihood. Once a

model has been fit to the data, one can use it to draw statistical inferences via both the fixed-

effects and covariance parameters.

As a first step in the regression analysis, a model was run by using all the variables and

terms, which is referred to as the full model. The residuals (i.e., difference between the true value

of the dependent variable and the value of the dependent variable predicted by the model) for

subglottal pressure, laryngeal airflow, and flow resistance are graphically displayed in Figures 1,

2, and 3, respectively.

Figure 1. Residual Analysis from Full Model of Subglottal Pressure 25

Figure 2. Residual Analysis from Full Model of Laryngeal Airflow

Figure 3. Residual Analysis from Full Model of Flow Resistance 26

The residuals in Figures 1, 2, and 3 were examined to determine if they satisfy the assumptions of regression analysis:

1) They are normally distributed:

The probability plots (upper right plot) show that the residuals of subglottal

pressure, airflow, and flow resistance deviate from normality.

2) They have mean equal to zero at each predicted mean:

The residuals of subglottal pressure, airflow, and flow resistance appear to have a

mean near zero (upper left plot).

3) They have a constant variance:

The residual vs. fits plot (upper left) shows a “megaphone” (increasing) effect

which signifies non-constant variance.

4) They are independent:

There does not seem to be any contradiction to the independence assumption.

Since the full regression model did not satisfy the assumptions of normal distribution and constant variance, the model was adjusted by using natural log values instead of the original values of the dependent variables. Residual analysis for log subglottal pressure, log laryngeal airflow, and log flow resistance are displayed in Figures 4, 5, and 6, respectively. 27

Figure 4. Residual Analysis from Full Model of Log Subglottal Pressure

Figure 5. Residual Analysis from Full Model of Log Laryngeal Airflow

Figure 6. Residual Analysis from Full Model of Log Flow Resistance

The residual plots in Figures 4, 5, and 6 indicate that both the normality and the constancy of variance for subglottal pressure, laryngeal airflow, and flow resistance have improved. The next step in the analysis was to reduce the full model to include the terms that were significant in the full model. The reduced models for log subglottal pressure, log airflow, and log flow resistance are listed in Tables 1, 2, and 3, respectively.

Table 1. Reduced Proc Mixed Model Terms for Log Subglottal Pressure source Fixed Main Effects adduction loudness adduction*source adduction*loudness Fixed 2-Factor Interactions gender*source source*loudness gender*loudness Random Factor subject

Table 2. Reduced Proc Mixed Model Terms for Log Laryngeal Airflow source Fixed Main Effects adduction loudness source*adduction source*loudness Fixed 2-Factor Interactions adduction*loudness source*gender Fixed 3-Factor Interactions Source*adduction*loudness Random Factor subject

Table 3. Reduced Proc Mixed Model Terms for Log Flow Resistance source Fixed Main Effects adduction loudness source*adduction Fixed 2-Factor Interactions source*loudness source*gender Fixed 3-Factor Interactions adduction*source*loudness Random Factor subject

The residual analysis for the reduced model in Tables 1, 2, and 3 was similar to the analysis shown in Figures 4, 5, and 6, respectively. Based on this reduced model, predictions and constructed confidence intervals were made for the true mean log subglottal pressure, log airflow, and log flow resistance for each of the treatment combinations. In order to draw useful conclusions, predictions and confidence intervals were transformed back into the natural physical units. Exponentiation was used to transform the log values of the dependent variables back to the original scale. It is noted that the exponentiation of the mean log value is the median value in physical units because in the normal distribution of the log values, the mean and median are identical. Bubble plots were used to graphically display the relationship between the four variables (i.e., source- phonation and whisper; adduction- breathy, normal, pressed; loudness- soft, medium, loud; and gender- males and females). For each circle pair in the following bubble plots, a dot will appear in the center if there was a significant difference between the log mean 30

phonation and log mean whisper for that comparison alone (disregarding multiple paired

comparison).

3.1 Research Question 1: Do subglottal pressure, flow, and flow resistance differ between

phonation and whisper relative to loudness and adduction in males and females?

Analysis of subglottal pressure: The bubble plot of Figure 7 shows the relationship between the 3 levels of adduction and 3 levels of loudness for predicted subglottal pressure in males and females. The area of each bubble is proportional to the predicted median value of subglottal pressure for that variable combination. Table 4 below gives the predicted median values of subglottal pressures for different combinations of terms.

Figure7. Predicted Median Subglottal Pressure from Table 1 Model

Table 4. Summary of Predicted Median Subglottal Pressure (cm H20), with 95% Confidence Intervals Soft Medium Loud Adduction Source Female Male Female Male Female Male Upper 9.849564 16.19505 12.96223 22.8787 21.85909 32.83374 Whisper Predicted 7.743702 11.91937 10.19793 16.84554 17.20242 24.18978 Lower 6.088079 8.77252 8.023136 12.40334 13.53777 17.82147 Pressed Upper 12.48887 16.37285 14.76447 20.77262 23.23645 27.82094 Phonation Predicted 9.825008 12.05546 11.6154 15.29514 18.27316 20.4834 Lower 7.729343 8.87653 9.137988 11.262 14.37003 15.08108 Upper 4.402896 7.239641 6.83846 12.07081 12.26895 18.4272 Whisper Predicted 3.462843 5.330127 5.380204 8.887341 9.650529 13.57042 Lower 2.723498 3.924263 4.232912 6.54346 7.590929 9.993726 Normal Upper 6.456434 8.464453 9.006125 12.67341 15.06333 18.04144 Phonation Predicted 5.079403 6.232517 7.084623 9.329017 11.85143 13.28493 Lower 3.996066 4.589106 5.573082 6.867179 9.324395 9.78244 Whisper Upper 5.258249 8.646259 7.98854 14.10464 13.68722 20.55955 Predicted 4.135703 6.365817 6.285859 10.38336 10.77661 15.1539 Lower 3.252802 4.686839 4.946089 7.643875 8.484944 11.16954 Breathy Phonation Upper 8.695008 11.39942 11.86624 16.69404 18.95525 22.7122 Predicted 6.840723 8.393688 9.333733 12.29064 14.92364 16.72873 Lower 5.38188 6.180491 7.341715 9.048726 11.74951 12.32159

By comparing the 95% confidence intervals (i.e., the difference between the “upper” and

“lower” values in Table 5) for whisper and phonation, one can determine which differences are

statistically significant if that were the only paired comparison. If a significant difference is

found for a treatment combination at the 95% confidence interval, it is marked with a dot in the

middle of the bubble pair in Figure 7. Only one dot was placed in the center of a bubble in

Figure 7 (for Breathy/Soft/Female). For example, consider the bubbles for the

Breathy/Loud/Female combination in Figure 7 (see cell with the arrow). For the given

combination, the predicted log pressures are 2.37738 and 2.70295 for Whisper and Phonation,

respectively (these are bolded in Table 5). These result in predicted pressures of e2.37738=

2.70295 10.77661 cm H20 and e = 14.92364 cm H20 (values bolded in Table 4), which correspond to the bubble areas (indicated by the arrow) in Figure 7. These two bubbles have a non- significant difference because of their overlapping 95% confidence intervals. 32

On the log scale, the 95% confidence intervals are (2.14, 2.62) for whisper and (2.46,

2.94) for phonation in Table 5. The conversion of intervals to the pressure scale was to

exponentiate the four log scale interval end points, which resulted in the intervals (8.48, 13.69)

for whisper and (11.75, 18.96) for phonation (see Tables 4 and 5). It is stated again that, as

Figure 7 indicates, there was only one significant difference between subglottal pressures for

whisper and phonation at any of the nine treatment combinations for either the males or females.

This case, for Breathy/Soft/Female, had intervals of (3.25, 5.26), median of 4.14, for whisper and

(1.99, 2.47), median of 6.84, for phonation (units in cm H2O). The results from Figure 7 suggest, then, that whisper and phonation do not tend to differ relative to subglottal pressure for any of the nine adduction-loudness conditions for either the males or the females (with the exception of female/breathy/loud, where whisper has lower Ps value).

Table 5. Predicted Values and 95% Confidence Intervals for Mean Log Subglottal Pressure and Median Subglottal Pressure by Treatment Based on Table 1 Model S Add Loud G StdErrPred Lower Pred Upper elower epred eupper Wh B S F 0.12231 1.17952 1.41966 1.65980 3.25280 4.13570 5.25825 Wh B S M 0.15595 1.54476 1.85094 2.15713 4.68684 6.36582 8.64626 Wh B M F 0.12209 1.59860 1.83830 2.07801 4.94609 6.28586 7.98854 Wh B M M 0.15601 2.03391 2.34020 2.64650 7.64388 10.38336 14.10464 Wh B L F 0.12177 2.13829 2.37738 2.61646 8.48494 10.77661 13.68722 Wh B L M 0.15538 2.41319 2.71826 3.02333 11.16954 15.15390 20.55955 Wh N S F 0.12233 1.00192 1.24209 1.48226 2.72350 3.46284 4.40290 Wh N S M 0.15595 1.36718 1.67338 1.97957 3.92426 5.33013 7.23964 Wh N M F 0.12216 1.44289 1.68273 1.92256 4.23291 5.38020 6.83846 Wh N M M 0.15594 1.87847 2.18463 2.49079 6.54346 8.88734 12.07081 Wh N L F 0.12227 2.02695 2.26701 2.50707 7.59093 9.65053 12.26895 Wh N L M 0.15582 2.30196 2.60789 2.91383 9.99373 13.57042 18.42720 Wh P S F 0.12252 1.80633 2.04688 2.28743 6.08808 7.74370 9.84956 Wh P S M 0.15613 2.17162 2.47817 2.78471 8.77252 11.91937 16.19505 Wh P M F 0.12216 2.08233 2.32218 2.56204 8.02314 10.19793 12.96223 Wh P M M 0.15592 2.51797 2.82409 3.13021 12.40334 16.84554 22.87870 Wh P L F 0.12202 2.60548 2.84505 3.08462 13.53777 17.20242 21.85909 Wh P L M 0.15561 2.88040 3.18593 3.49146 17.82147 24.18978 32.83374 Ph B S F 0.12217 1.68304 1.92289 2.16275 5.38188 6.84072 8.69501 Ph B S M 0.15590 1.82140 2.12748 2.43356 6.18049 8.39369 11.39942 Ph B M F 0.12227 1.99357 2.23364 2.47370 7.34172 9.33373 11.86624 Ph B M M 0.15596 2.20262 2.50884 2.81505 9.04873 12.29064 16.69404 Ph B L F 0.12180 2.46381 2.70295 2.94208 11.74951 14.92364 18.95525 Ph B L M 0.15574 2.51135 2.81713 3.12290 12.32159 16.72873 22.71220 Ph N S F 0.12218 1.38531 1.62519 1.86508 3.99607 5.07940 6.45643 Ph N S M 0.15590 1.52369 1.82978 2.13588 4.58911 6.23252 8.46445 Ph N M F 0.12223 1.71795 1.95793 2.19791 5.57308 7.08462 9.00613 Ph N M M 0.15605 1.92675 2.23313 2.53951 6.86718 9.32902 12.67341 Ph N L F 0.12214 2.23263 2.47245 2.71226 9.32440 11.85143 15.06333 Ph N L M 0.15588 2.28059 2.58663 2.89267 9.78244 13.28493 18.04144 Ph P S F 0.12219 2.04502 2.28493 2.52484 7.72934 9.82501 12.48887 Ph P S M 0.15591 2.18341 2.48952 2.79562 8.87653 12.05546 16.37285 Ph P M F 0.12218 2.21244 2.45233 2.69222 9.13799 11.61540 14.76447 Ph P M M 0.15591 2.42143 2.72754 3.03364 11.26200 15.29514 20.77262 Ph P L F 0.12239 2.66515 2.90543 3.14572 14.37003 18.27316 23.23645 Ph P L M 0.15594 2.71344 3.01962 3.32579 15.08108 20.48340 27.82094 S= Source (Wh- whisper; Ph-Phonation); Add= Adduction (B- Breathy; N-Normal; P-Pressed); Loud= Loudness (S-Soft; M-Medium; L-Loud); G=Gender (M-Male; F-Female) 34

Analysis of glottal airflow: The bubble plot of Figure 8 below shows the relationship between the 3 levels of adduction and 3 levels of loudness for predicted airflow in males and females. The area of each bubble in Figure 8 is proportional to the predicted value of airflow for that variable combination. Table 6 gives the predicted airflow values for different combination of terms.

Figure 8. Predicted Airflow from Table 2 Model

Table 6. Summary of Predicted Laryngeal Airflow Values (cc/s) Soft Medium Loud Adduction Source Female Male Female Male Female Male Upper 375.206 351.606 717.352 672.586 971.567 911.019 Whisper Predicted 310.692 280.060 595.547 536.832 807.712 728.079 Lower 257.271 223.073 494.425 428.478 671.492 581.875 Pressed Upper 282.214 396.038 241.115 338.3646 248.8695 348.959 Phonation Predicted 234.289 316.085 200.170 270.054 206.2163 278.211 Lower 194.503 252.273 166.178 215.535 170.8733 221.807 Upper 407.192 381.630 702.549 658.707 1252.361 1173.74 Whisper Predicted 337.743 304.445 583.258 525.754 1038.763 936.350 Lower 280.139 242.870 484.222 419.636 861.595 746.971 Normal Upper 245.039 343.871 228.253 320.405 203.2105 285.171 Phonation Predicted 203.427 274.449 189.373 255.4881 168.7019 227.600 Lower 168.882 219.043 157.115 203.7239 140.0535 181.651 Whisper Upper 759.542 711.870 1071.76 1005.556 1805.489 1692.75 Predicted 630.001 567.888 890.016 802.268 1503.646 1355.4 Lower 522.553 453.028 739.086 640.0788 1252.265 1085.27 Breathy Phonation Upper 578.140 811.321 645.097 904.924 969.869 1362.48 Predicted 479.962 647.530 535.059 721.862 807.107 1088.89 Lower 398.457 516.805 443.791 575.833 671.660 870.234

Significant differences between the log airflow values for whisper and phonation were calculated using the exponentiated upper and lower limits listed in Table 7. The significant differences for airflow are indicated by using a dot in the center of the bubbles in the bubble plot for predicted airflow (Figure 8).

Table 7. Predicted Values and 95% Confidence Intervals for Mean Log Flow and Median Glottal Flow by Treatment Based on Table 2 Model S Add Loud G StdErrPred Lower Pred Upper elower epred eupper Wh B S F 0.09524 6.258728 6.445722 6.632716 522.5538 630.0013 759.5421 Wh B S M 0.115092 6.115955 6.341926 6.567896 453.0285 567.8889 711.8708 Wh B M F 0.094645 6.605415 6.79124 6.977064 739.0865 890.0162 1071.767 Wh B M M 0.115032 6.461591 6.687444 6.913296 640.0788 802.2686 1005.556 Wh B L F 0.093175 7.132709 7.315648 7.498587 1252.265 1503.646 1805.489 Wh B L M 0.113203 6.989591 7.211852 7.434113 1085.278 1355.4 1692.755 Wh N S F 0.095244 5.635286 5.822287 6.009287 280.1391 337.7435 407.1929 Wh N S M 0.115089 5.492527 5.718491 5.944454 242.8702 304.445 381.6309 Wh N M F 0.094778 6.182544 6.36863 6.554715 484.2224 583.2581 702.5491 Wh N M M 0.114825 6.039388 6.264834 6.490279 419.6363 525.7541 658.7071 Wh N L F 0.095244 6.758786 6.945786 7.132786 861.5955 1038.763 1252.361 Wh N L M 0.115088 6.616027 6.84199 7.067953 746.9712 936.3505 1173.743 Wh P S F 0.096096 5.55013 5.738803 5.927476 257.271 310.6923 375.2064 Wh P S M 0.115874 5.407501 5.635007 5.862513 223.0734 280.0609 351.6067 Wh P M F 0.094778 6.203396 6.389482 6.575567 494.4254 595.5479 717.3525 Wh P M M 0.114825 6.060241 6.285686 6.511131 428.4785 536.8323 672.5867 Wh P L F 0.094074 6.509503 6.694206 6.87891 671.4924 807.7127 971.567 Wh P L M 0.114167 6.366256 6.59041 6.814564 581.8754 728.0796 911.0195 Ph B S F 0.09479 5.9876 6.173709 6.359818 398.4572 479.9629 578.1409 Ph B S M 0.114852 6.247667 6.473166 6.698664 516.8056 647.5302 811.3213 Ph B M F 0.095255 6.095355 6.282378 6.469402 443.7916 535.0597 645.0977 Ph B M M 0.115116 6.355819 6.581835 6.807851 575.8336 721.8628 904.9245 Ph B L F 0.093565 6.509753 6.693457 6.877162 671.6602 807.1078 969.8699 Ph B L M 0.114165 6.768763 6.992914 7.217065 870.2347 1088.89 1362.484 Ph N S F 0.09479 5.129203 5.315312 5.501421 168.8825 203.4279 245.0398 Ph N S M 0.114852 5.38927 5.614768 5.840267 219.0434 274.4498 343.8712 Ph N M F 0.095111 5.05698 5.243719 5.430458 157.1153 189.3731 228.2538 Ph N M M 0.115316 5.316766 5.543176 5.769586 203.7239 255.4881 320.405 Ph N L F 0.09479 4.942025 5.128134 5.314242 140.0535 168.7019 203.2105 Ph N L M 0.114852 5.202092 5.42759 5.653089 181.6518 227.6001 285.171 Ph P S F 0.09479 5.270448 5.456557 5.642666 194.5031 234.2894 282.214 Ph P S M 0.114852 5.530515 5.756014 5.981512 252.2738 316.0858 396.0388 Ph P M F 0.09479 5.11306 5.299169 5.485278 166.1781 200.1704 241.1159 Ph P M M 0.114852 5.373127 5.598625 5.824124 215.5357 270.0549 338.3646 Ph P L F 0.095754 5.140923 5.328926 5.516929 170.8733 206.2163 248.8695 Ph P L M 0.115399 5.40181 5.628382 5.854954 221.8076 278.2117 348.959 S= Source (Wh- whisper; Ph-Phonation); Add= Adduction (B- Breathy; N-Normal; P-Pressed); Loud= Loudness (S-Soft; M-Medium; L-Loud); G=Gender (M-Male; F-Female)

Figure 8 indicates significant differences in airflow between whisper and phonation for

11 out of 18 combinations (Table 8), with airflow changes being higher for whisper compared to phonation. Thus, for more than half of the cases (61%), the flow was significantly greater during whisper than phonation. Phonation had more flow than whisper for only two cases

(Pressed/Soft/Male and Breathy/Soft/Male). Only one of the 6 soft conditions was significantly different but 5 of the 6 medium and loud conditions were significantly different.

Table 8. Terms with Significant Difference in Airflow between Whisper and Phonation Adduction Loudness Gender Pressed Medium Female Pressed Medium Male Pressed Loud Female Pressed Loud Male Normal Soft Female Normal Medium Female Normal Medium Male Normal Loud Female Normal Loud Male Breathy Medium Female Breathy Loud Female

The results from Figure 8 suggest, then, that whisper and phonation tend to differ relative to laryngeal airflow for medium and loud productions (only 2 out 12 exceptions), but not for soft productions (with one exception) for both males and females.

Analysis of flow resistance: The bubble plot of Figure 9 shows the relationship between the three levels of adduction and three levels of loudness for predicted flow resistance in males and females. The area of each bubble in Figure 9 is proportional to the predicted value of flow resistance for that variable combination. Table 9 gives the predicted flow resistance values for the different combinations.

Figure 9. Predicted Flow Resistance from the Table 3 Model

Table 9. Summary of Predicted Flow Resistance Values [kPa/(L/s)] Ad- Soft Medium Loud Source duction Female Male Female Male Female Male Upper 3.759686 7.029658 2.487781 4.653554 2.998642 5.609718 Whisper Predicted 2.566451 4.34249 1.701348 2.878717 2.052715 3.473238 Lower 1.75192 2.682523 1.16352 1.780791 1.405183 2.150444 Pressed Upper 5.923901 5.912264 8.917264 8.899746 12.38955 12.35759 Phonation Predicted 4.05118 3.65723 6.098251 5.505237 8.461445 7.638627 Lower 2.770481 2.262303 4.170412 3.40545 5.778746 4.721682 Upper 1.448981 2.709606 1.393464 2.606563 1.353938 2.531876 Whisper Predicted 0.990288 1.675589 0.952964 1.612436 0.925333 1.565683 Lower 0.676801 1.036165 0.651714 0.997462 0.632408 0.9682 Normal Upper 3.725812 3.718492 5.484328 5.474498 9.668295 9.649302 Phonation Predicted 2.547972 2.300199 3.748893 3.384338 6.611859 5.9689 Lower 1.742482 1.422865 2.562611 2.0922 4.521654 3.692264 Whisper Upper 0.968746 1.81158 1.069493 2.001479 0.983185 1.839231 Predicted 0.662081 1.120255 0.731542 1.237784 0.673872 1.140206 0.452493 0.692749 0.50038 0.765489 0.46187 0.706855 Breathy Lower Phonation Upper 2.06002 2.055973 2.57152 2.565707 2.646332 2.643198 Predicted 1.408786 1.271791 1.757446 1.586546 1.812814 1.63653 Lower 0.963427 0.786709 1.201086 0.981066 1.24183 1.013254

Table 10. Predicted Values and 95% Confidence Intervals for Mean Log Resistance and Median S Add Loud G StdErrPred Lower Pred Upper elower epred eupper Wh B S F 0.193856 -0.79298 -0.41237 -0.03175 0.452493 0.662081 0.968746 Wh B S M 0.244803 -0.36709 0.113556 0.5942 0.692749 1.120255 1.81158 Wh B M F 0.193434 -0.69239 -0.3126 0.067185 0.50038 0.731542 1.069493 Wh B M M 0.244762 -0.26724 0.213323 0.693886 0.765489 1.237784 2.001479 Wh B L F 0.192401 -0.77247 -0.39471 -0.01696 0.46187 0.673872 0.983185 Wh B L M 0.243527 -0.34693 0.131209 0.609348 0.706855 1.140206 1.839231 Wh N S F 0.193858 -0.39038 -0.00976 0.37086 0.676801 0.990288 1.448981 Wh N S M 0.244801 0.035526 0.516165 0.996803 1.036165 1.675589 2.709606 Wh N M F 0.193528 -0.42815 -0.04818 0.331793 0.651714 0.952964 1.393464 Wh N M M 0.244621 -0.00254 0.477746 0.958032 0.997462 1.612436 2.606563 Wh N L F 0.193858 -0.45822 -0.0776 0.303018 0.632408 0.925333 1.353938 Wh N L M 0.244801 -0.03232 0.448322 0.928961 0.9682 1.565683 2.531876 Wh P S F 0.194466 0.560713 0.942524 1.324335 1.75192 2.566451 3.759686 Wh P S M 0.245336 0.986758 1.468448 1.950138 2.682523 4.34249 7.029658 Wh P M F 0.193528 0.15145 0.531421 0.911391 1.16352 1.701348 2.487781 Wh P M M 0.244621 0.577058 1.057345 1.537631 1.780791 2.878717 4.653554 Wh P L F 0.193032 0.340167 0.719163 1.09816 1.405183 2.052715 2.998642 Wh P L M 0.244176 0.765674 1.245087 1.7245 2.150444 3.473238 5.609718 Ph B S F 0.193536 -0.03726 0.342728 0.722716 0.963427 1.408786 2.06002 Ph B S M 0.24464 -0.2399 0.240426 0.720749 0.786709 1.271791 2.055973 Ph B M F 0.193867 0.183226 0.563862 0.944497 1.201086 1.757446 2.57152 Ph B M M 0.244819 -0.01912 0.461559 0.942234 0.981066 1.586546 2.565707 Ph B L F 0.192674 0.216586 0.59488 0.973175 1.24183 1.812814 2.646332 Ph B L M 0.244175 0.013167 0.492578 0.97199 1.013254 1.63653 2.643198 Ph N S F 0.193536 0.555311 0.935298 1.315285 1.742482 2.547972 3.725812 Ph N S M 0.24464 0.352673 0.832995 1.313318 1.422865 2.300199 3.718492 Ph N M F 0.193764 0.941027 1.321461 1.701895 2.562611 3.748893 5.484328 Ph N M M 0.244955 0.738216 1.219158 1.700101 2.0922 3.384338 5.474498 Ph N L F 0.193536 1.508878 1.888865 2.268852 4.521654 6.611859 9.668295 Ph N L M 0.24464 1.30624 1.786563 2.266886 3.692264 5.9689 9.649302 Ph P S F 0.193536 1.019021 1.399008 1.778995 2.770481 4.05118 5.923901 Ph P S M 0.24464 0.816383 1.296706 1.777029 2.262303 3.65723 5.912264 Ph P M F 0.193536 1.428015 1.808002 2.187989 4.170412 6.098251 8.917264 Ph P M M 0.24464 1.225377 1.7057 2.186023 3.40545 5.505237 8.899746 Ph P L F 0.194222 1.754187 2.13552 2.516853 5.778746 8.461445 12.38955 Ph P L M 0.245012 1.552165 2.033218 2.514271 4.721682 7.638627 12.35759 S= Source (Wh- whisper; Ph-Phonation); Add= Adduction (B- Breathy; N-Normal; P-Pressed); Loud= Loudness (S- Soft; M-Medium; L-Loud); G=Gender (M-Male; F-Female)

The significant differences for flow resistance between whisper and phonation are indicated by using a dot in the center of the bubbles in the bubble plot (Figure 9). Only 8 out of the 18 treatment combinations (44%; See Table 11) had significant flow resistance differences between whisper and phonation. Flow resistance was always greater for phonation compared to whisper for those 8 combinations. It is of interest that 7 out of those 8 treatment combinations were females.

Table 11. Terms with Significant Differences between the Flow Resistance of Whisper and Phonation Adduction Loudness Gender Pressed Medium Female Pressed Loud Female Normal Soft Female Normal Medium Female Normal Loud Female Normal Loud Male Breathy Medium Female Breathy Loud Female

The results from Figure 9 suggest, then, whisper and phonation tend to differ relative to flow resistance for females (with 2/9 exceptions) but not for males (with one exception).

Phonation had higher flow resistances compared to whisper for 17/18 treatment combinations.

Verification of the reduced model:

The adequacy of the reduced model was tested by comparing the predicted median values for each combination with the observed sample medians. Medians were used (instead of means) as a measure of central tendency because log transformations were applied. Figures 10, 11, and

12 show the sample medians of subglottal pressure, glottal airflow, and flow resistance, respectively between whisper and phonation (without including the center dots).

Figure 10. Sample Medians of Subglottal Pressure by Treatment

Figure 11. Sample Medians of Laryngeal Airflow by Treatment 42

Figure12. Sample Medians of Flow Resistance by Treatment

Bubble plots of model-predicted subglottal pressure (Figure 7), airflow values (Figure 8), and flow resistance (Figure 9) are similar to the bubble plots of medians of subglottal pressure

(Figure 10), airflow (Figure 11), and flow resistance (Figure 12). This suggests that the reduced model appears consistent with the raw data. It is noted that the reduced model takes into account all of the relevant inherent relationships among the data, and thus intrinsically creates a structure of relationships that is simpler than the data would tend to show. Thus, the predicted median values may create a pattern of results that is more “orderly” than the data would suggest.

3.2.Within-subject and between-subjects variability

Subglottal pressure: To analyze the within-subject and between-subject variability, first multiple observations from the same subject were collected on the same treatment combination.

A Proc Mixed estimate for the variance of those readings on the log pressure scale was 0.07. 43

Second, multiple observations were collected on the same treatment where each observation was

taken from a new subject. A Proc Mixed estimate for the variance of those readings on the log

scale was 0.13. Thus 54% of the subglottal pressure variation estimate of 0.13 = 0.07+ 0.06 was due to the repeatability on the same subject. The other 46% of subglottal pressure variation was due to reproducibility between subjects.

Glottal airflow: A Proc Mixed estimate for the variance of multiple observations from the same subject on the log airflow scale within a subject was 0.03. Second, multiple observations were collected on the same treatment where each observation was taken from a new subject. A

Proc Mixed estimate for the variance on the log scale was 0.15. Thus, 20% of the airflow variation estimate of 0.15 = 0.03 + 0.12 was due to the repeatability on the same subject. The other 80% of airflow variation was due to reproducibility between subjects.

Flow resistance: A Proc Mixed estimate for the variance of the flow resistance readings on the log resistance scale for the same subject was 0.16. Second, for multiple observations on the same treatment where each observation was taken from a new subject, the Proc Mixed estimate for the variance on the log scale was 0.33. So 48% of the flow resistance variation estimate of 0.33 = 0.16 + 0.17 was due to the repeatability on the same subject. The other 52% of flow resistance variation was due to reproducibility between subjects.

Thus, the within-subject and between-subject variability was similar for pressure and flow resistance. However, for the median airflow, the within-subject variability was smaller than the between-subject variability.

3.3. Research Question 2: Do subglottal pressure, flow, and flow resistance vary across

the three loudness levels for phonation and for whisper in males and females?

Subglottal Pressure (Ps): Ps increased as loudness increased from soft to medium to loud in all cases, that is, for males and females, and for phonation and whisper (see Figures 13-

18 and Table 12). Males had greater Ps than females in all cases. Males increased Ps by a factor of 1.226, 1.31, and 1.12 for all soft, medium, and loud phonation respectively compared to females. For whisper, males increased Ps by a factor of 1.54, 1.65, and 1.41 for all soft, medium, and loud conditions respectively compared to females.

Mean Flow: In pressed phonation, mean flow decreased as loudness increased from soft to medium, but increased from medium to loud for both males and females (see Figure 14 and

Table 12). In normal phonation, mean flow decreased when loudness increased from soft to medium to loud for both males and females (see Figure 18). However, in breathy phonation, mean flow increased when loudness increased from soft to medium to loud for both males and females (see Figure 16). Similar to breathy phonation, for whisper, mean flow increased from soft to medium to loud for all 3 levels of adduction in both males and females (see Figures 13,

15, and 17).

Females had greater flows than males in all cases of whisper, unlike in phonation where males had higher flows. Males increased mean airflow by a factor of 1.35 for all soft, medium, and loud phonation compared to females. For whisper, females increased Ps by a factor of 0.9 for all soft, medium, and loud conditions compared to males. The values of subglottal pressure, airflows, and flow resistances across loudness in males and females are given in Table 12.

Table 12. Predicted Median Subglottal Pressure (Ps), Airflows (Fl), and Flow Resistances (R) across Loudness in Males (M) and Females (F). Also included are ratios of the predicted median values for the male subjects divided by the female subjects.

Fl Fl Ps (F) Ps (M) Ps Fl R (F) R (M) R Adduction Loudness (F) (M) cmH 0 cmH 0 M/F M/F kPa/(L/s) kPa/(L/s) M/F 2 2 cc/s cc/s Pressed Soft 9.83 12.06 1.23 234 316 1.35 4.05 3.66 0.9 Phonation Medium 11.62 15.3 1.32 200 270 1.35 6.1 5.51 0.9

Loud 18.27 20.48 1.12 206 278 1.35 8.46 7.64 0.9

Normal Soft 5.08 6.23 1.23 203 274 1.35 2.58 2.3 0.9 Phonation Medium 7.08 9.33 1.32 189 255 1.35 3.75 3.38 0.9

Loud 11.85 13.28 1.12 169 228 1.35 6.61 5.97 0.9

Breathy Soft 6.84 8.39 1.23 480 648 1.35 1.41 1.27 0.9 Phonation Medium 9.33 12.29 1.32 535 722 1.35 1.76 1.59 0.9

Loud 14.92 16.73 1.12 807 1089 1.35 1.81 1.64 0.9

Pressed Soft 7.74 11.91 1.54 311 280 0.9 2.57 4.34 1.69 Whisper Medium 10.2 16.85 1.65 596 537 0.9 1.7 2.88 1.69

Loud 17.2 24.19 1.41 808 728 0.9 2.05 3.47 1.69

Normal Soft 3.46 5.33 1.54 338 304 0.9 0.99 1.68 1.69 Whisper Medium 5.38 8.89 1.65 583 526 0.9 0.95 1.61 1.69

Loud 9.65 13.57 1.41 1039 936 0.9 0.93 1.57 1.69

Breathy Soft 4.14 6.37 1.54 630 568 0.9 0.66 1.12 1.69 Whisper Medium 6.29 10.38 1.65 890 802 0.9 0.73 1.24 1.69

10.78 15.15 1.41 1503 1355 0.9 0.67 1.14 1.69 Loud

Figure 13 through Figure 36 show the pressure-flow interaction data for all the conditions of this study. There are descriptive trends that appear to provide further structure and insight into the data. In Figures 13-18, the predicted 95% confidence intervals for pressure and flow are indicated as error bars along the X-axis and Y-axis respectively. Appendix II includes figures

(Figures A5- A12) showing the pressure-flow relationship for individual subjects. 46

Pressed Whisper 1000 soft females 800 medium females 600 loud females 400 soft males

Flow (cc/s) (cc/s) Flow 200 medium males 0 0 10 20 30 40 loud males Pressure (cmH20)

Figure 13: Pressure vs. Flow Relationship across Loudness in Pressed Whisper

Pressed Phonation 400 soft females

medium females

200 loud females

soft males Flow (cc/s) (cc/s) Flow

medium males 0 0 5 10 15 20 25 30 loud males Pressure (cmH20)

Figure 14: Pressure vs. Flow Relationship across Loudness in Pressed Phonation

Figures 13 and 14 contrast the pressure-flow relations for pressed whisper and pressed phonation, respectively. For pressed whisper, as Ps increased, it is obvious that both pressure and flow increase, with female values of flow higher than for the males. That is, for any value of pressure, the figure suggests that females produce more flow during pressed whisper than males.

In addition, the pressure-flow data for the soft productions for both the males and females

(predicted median values plus and minus the 95% confidence interval [CI] values) are displayed far from the corresponding loud values, the latter being higher in both pressure and flow, suggesting significantly different values. If the data for the males and females are combined, a general “eye ball approximation” equation for the relationship between flow and pressure is approximately Flow (cc/s) = 37*Ps (cm H2O) (noting that the scatter and separation does not

make this equation highly predictive).

In contrast to Figure 13, Figure 14 for pressed phonation shows median values for

females that are lower than all male median values. However, the overlap of the 95% CIs gives

low confidence that the median value differences are meaningfully different. Furthermore, the

data tend to show that the median values of flow may decrease as Ps increases, suggesting that

adduction increases significantly as Ps increases. But the better impression would be that the

flows are relatively constant and not necessarily different between males and females, due to the

wide overlap of CI intervals among the data.

Another relatively immediate observation when comparing the data shown in Figures 13

and 14 are the ranges of values of the pressures and flows between pressed whisper and

phonation, namely, the pressures overlap greatly between approximately 5 and 35 cm H2O

(noticing that the figures deal with loudness increase and thus a relatively large range of Ps

values is expected), but the flows for pressed phonation are essentially low (200 to 400 cc/s), 48

which is in the range of only the soft pressed whisper. Thus, pressed whisper and phonation

across loudness do not differ in the (wide) range of pressures, but the flows for medium and loud

pressed whisper are above essentially all the flows for pressed phonation, and the flows for

pressed phonation do not appear to be a strong function of Ps. There most likely was a posterior

gap in the productions of the subjects for pressed productions that remained in pressed whisper

compared to pressed phonation, an idea that constitutes a hypothesis for a future study.

Examination of Figures 15 and 16 for breathy whisper and breathy phonation suggest

similar pressure-flow relationships – higher flows for females in breathy whisper for any specific

Ps value, with a strong indication of flow increase with pressure increase; no strong distinction

between males and females for breathy phonation; and a similar range of Ps values for males,

females, whisper, and phonation. In contrast with pressed whisper and phonation, the flow

ranges are more similar in these figures, and the breathy phonation pressure-flow relation appears to form a strong function for the two genders combined that increases for both flow and pressure, viz., the line Flow(cc/s) = 62*Ps(cm H2O). A general fit for the breathy whisper data is

approximately Flow(cc/s) = 110*Ps(cm H2O), suggesting that flow increases with Ps faster for

breathy whisper than for breathy phonation or pressed whisper discussed above.

Breathy Whisper soft females 2000 1800 medium females 1600 1400 1200 loud females 1000

800 soft males 600

Flow (cc/s) (cc/s) Flow 400 medium males 200 0 0 5 10 15 20 25 loud males Pressure (cmH20)

Figure 15: Pressure vs. Flow Relationship across Loudness in Breathy Whisper

Breathy Phonation 1400 soft females 1200

1000 medium females

800 loud females 600

400 soft males Flow (cc/s) (cc/s) Flow 200 medium males 0 0 5 10 15 20 25 loud males Pressure (cmH20)

Figure 16: Pressure vs. Flow Relationship across Loudness in Breathy Phonation 50

Normal Whisper 1400 soft females 1200

1000 medium females

800 loud females 600

400 soft males Flow (cc/s) (cc/s) Flow 200 medium males 0 0 5 10 15 20 loud males Pressure (cmH20)

Figure 17: Pressure vs. Flow Relationship across Loudness in Normal Whisper

Normal Phonation 600 soft females

medium females 400

loud females

200 soft males Flow (cc/s) (cc/s) Flow

medium males 0 0 5 10 15 20 loud males Pressure (cmH20)

Figure 18: Pressure vs. Flow relationship across Loudness in Normal Phonation

Figures 17 and 18 for normal whisper and normal phonation across loudness suggest the same theme for whisper as Figures 13 and 15, namely, that female flow values are higher than for males so that at any Ps value, it would be expected that females may have higher flows for normal whisper. Taking males and females together, the data of Figure 17 suggest the rough relation of Flow (cc/s) = 84*Ps (cm H2O) (a value also less than for breathy whisper). Figure 18 for normal phonation, however, suggests a relationship similar to what is seen for pressed phonation, where flow tends to decrease as pressure increases, since the predicted median values do so for both genders. However, because of the significant overlap of the 95% CIs, the relationship is not only considered weak, but essentially nearly “constant” within a narrow range of about 100 to 400 cc/s.

Flow resistance: Figures 19-24 show the relationship between pressures and the flow resistance variable across the pressed, breathy, and normal whisper and phonation productions.

There is a tendency, as expected, for Ps to increase from soft to medium to loud productions of both whisper and phonation. The figures suggest, however, that the pressures do not appear to differ between the genders in a significant practical point of view. Furthermore, because the flow resistance values have such wide CI intervals that the overlap greatly, the only practical decision appears to be that flow resistance does not differentiate loudness or gender within any of the adduction-source categories. Furthermore, at first look, Figures 19 and 20 for pressed whisper and phonation, respectively, appear to give much higher flow resistance values than the other figures (for breathy and normal), but again the wide range of CIs tend to reduce any enthusiasm for that conclusion. For phonation, females increased flow resistance by a factor of 0.9 compared to males for all soft, medium, and loud conditions. For whisper, males increased flow resistance by a factor of 1.69 compared to females for all soft, medium, and loud conditions. However, as 52 mentioned earlier, the overlap in each figure is remarkable; suggesting that it would be risky to assume that there is any practical significant difference between the two conditions despite the trends for the predicted medians.

Pressed Whisper 8 soft females

6 medium females loud females 4

soft males [kPa/(L/s)] [kPa/(L/s)] 2 Flow Resistance FlowResistance medium males

0 loud males 0 5 10 15 20 25 30 35 Pressure (cmH20) .

Figure 19: Pressure vs. Flow Resistance across Loudness in Pressed Whisper

Pressed Phonation 14

soft females 12

10 medium females

8 loud females 6 [kPa/(L/s)] [kPa/(L/s)] soft males

Flow Resistance FlowResistance 4 2 medium males 0 0 10 20 30 loud males Pressure (cmH20) . Figure 20: Pressure vs. Flow Resistance across Loudness in Pressed Phonation 53

Breathy Whisper

soft females 2 medium females

loud females

soft males

medium males 0 0 5 10 15 20 loud males

Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance Pressure (cmH20)

Figure 21: Pressure vs. Flow Resistance across Loudness in Breathy Whisper

Breathy Phonation 4 soft females

medium females

2 loud females

soft males

medium males 0 0 5 10 15 20 25 Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance Pressure (cmH20) loud males

Figure 22: Pressure vs. Flow Resistance across Loudness in Breathy Phonation

Normal Whisper 4 soft females

medium females

2 loud females

soft males

medium males 0 0 5 10 15 20 Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance loud males Pressure (cmH20)

Figure 23: Pressure vs. Flow Resistance across Loudness in Normal Whisper

Normal Phonation 12 soft females 10

medium females 8

6 loud females

4 soft males

2 medium males 0 0 5 10 15 20 loud males Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance Pressure (cmH20)

Figure 24: Pressure vs. Flow Resistance across Loudness in Normal Phonation

3.4. Research Question 3: Do subglottal pressure, flow, and flow resistance vary across

the three adduction levels for phonation and whisper in males and females?

Subglottal Pressure (Ps): Ps was lowest for normal adduction, increased for breathy, and was greatest for pressed, for both phonation and whisper for all 12 conditions (2 subjects x 3 loudness x 2 genders). At each level of loudness, males increased Ps by a factor of 1.22, 1.31, and 1.12 compared to females for breathy, normal, and pressed phonation respectively.

Mean Flow: In all cases of phonation, airflow was lowest for normal adduction , increased for pressed, and was greatest for breathy phonation (see Figures 26, 28, and 30).

Medium loudness whisper was similar to phonation, i.e. breathy > pressed > normal adduction

(see Figure 27). In soft and loud whisper, airflow decreased as adduction increased from breathy to normal to pressed (see Figures 25 and 29).

In all cases of phonation, males had greater airflow than females. For phonation, males increased airflow by a factor of 1.35 compared to females at each level of adduction for all 3 loudness levels. Unlike phonation, females had greater airflow than males for all whisper conditions. For whisper, females increased airflow by a factor of 0.9 compared to males at each level of adduction for all 3 loudness levels. The predicted Ps, airflows, and flow resistances across adduction are indicated in Table 13.

Table 13. Predicted Median Subglottal Pressure (Ps), Airflows (Fl), and Flow Resistances (R) across Adduction in Males (M) and Females (F). Also included are ratios of the predicted median values for the male subjects divided by the female subjects.

Fl Fl Ps (F) Ps (M) Ps Fl R (F) R (M) R Loudness Adduction (F) (M) cmH 0 cmH 0 M/F M/F kPa/(L/s) kPa/(L/s) M/F 2 2 cc/s cc/s Soft Breathy 6.84 8.39 1.23 480 648 1.35 1.41 1.27 0.9 Phonation Normal 5.08 6.23 1.23 203 274 1.35 2.58 2.3 0.9

Pressed 9.83 12.06 1.23 234 316 1.35 4.05 3.66 0.9

Medium Breathy 9.33 12.29 1.32 535 722 1.35 1.76 1.59 0.9 Phonation Normal 7.08 9.33 1.32 189 255 1.35 3.75 3.38 0.9

Pressed 11.62 15.3 1.32 200 270 1.35 6.1 5.51 0.9

Loud Breathy 14.92 16.73 1.12 807 1089 1.35 1.81 1.64 0.9 Phonation Normal 11.85 13.28 1.12 169 228 1.35 6.61 5.97 0.9

Pressed 18.27 20.48 1.12 206 278 1.35 8.46 7.64 0.9

Soft Breathy 4.14 6.37 1.54 630 568 0.9 0.66 1.12 1.69 Whisper Normal 3.46 5.33 1.54 338 304 0.9 0.99 1.68 1.69

Pressed 7.74 11.91 1.54 311 280 0.9 2.57 4.34 1.69

Medium Breathy 6.29 10.38 1.65 890 802 0.9 0.73 1.24 1.69 Whisper Normal 5.38 8.89 1.65 583 526 0.9 0.95 1.61 1.69

Pressed 10.2 16.85 1.65 596 537 0.9 1.7 2.88 1.69

Loud Breathy 10.78 8.39 1.41 1503 1355 0.9 0.67 1.14 1.69 Whisper Normal 9.65 6.23 1.41 1039 936 0.9 0.93 1.57 1.69

17.2 12.06 1.41 808 728 0.9 2.05 3.47 1.69 Pressed

Figures 25-36 have adduction as the parameter and show median values and 95% confidence intervals (CIs) to determine a general impression of the data. The CIs indicating variance with these limited data sets are typically wide, and help to show trends but it is important to not overstate the results of this study. An interesting observation across all of these figures is that, although the median values of Ps are typically higher for the males, males and 57 females typically do not seem to differ significantly for Ps, flow, or flow resistance due to their median values often being relatively close to each other, and the CIs typically showing much overlap in values. A second general observation is that breathy productions (both whisper and phonation) tend to have higher flows than for pressed and normal adduction levels. For most cases there appears to be a large difference (by a factor of 2 or more) between the median values for breathy productions and the other two (normal and pressed), as in Figures 25, 26, 28-30. It is also clear from Figures 25, 26, 28-30 that the flow values for normal and pressed productions do not appear to be practically different, despite the usual thought that pressed productions should have less flow (as suggested in Figure 29 for loud whisper). This again may be due to a posterior gap during the pressed phonations.

Soft Whisper 800 pressed females

600 normal females

400 breathy females

pressed males 200 Flow (cc/s) (cc/s) Flow

normal males 0 0 5 10 15 20 breathy males Pressure (cmH20)

Figure 25: Pressure vs. Flow Relationship across Adduction in Soft Whisper

Soft Phonation 1000 pressed female 800 normal females 600 breathy females 400 pressed males

Flow (cc/s) (cc/s) Flow 200 normal males 0 0 5 10 15 20 breathy males Pressure (cmH20)

Figure 26: Pressure vs. Flow Relationship across Adduction in Soft Phonation

Medium Whisper 1200 pressed female 1000

normal females 800

600 Breathy females

400 pressed males Flow (cc/s) (cc/s) Flow 200 normal males 0 0 5 10 15 20 25 breathy males Pressure (cmH20)

Figure 27: Pressure vs. Flow Relationship across Adduction in Medium Whisper

Medium Phonation 1000 pressed female 800 normal females 600 breathy females 400 pressed males Flow (cc/s) (cc/s) Flow 200 normal males 0 0 5 10 15 20 25 breathy males Pressure (cmH20)

Figure 28: Pressure vs. Flow Relationship across Adduction in Medium Phonation

Loud Whisper 2000 1800 pressed female 1600 1400 normal females 1200 1000 breathy females 800 600 pressed males Flow (cc/s) (cc/s) Flow 400 200 normal males 0 0 5 10 15 20 25 30 35 breathy males Pressure (cmH20)

Figure 29: Pressure vs. Flow Relationship across Adduction in Loud Whisper

Loud Phonation 1400 pressed female 1200

1000 normal females

800 breathy females 600

400 pressed males Flow (cc/s) (cc/s) Flow 200 normal males 0 0 5 10 15 20 25 30 35 breathy males Pressure (cmH20)

Figure 30: Pressure vs. Flow Relationship across Adduction in Loud Phonation

Flow resistance: Figures 31-36 show the data for the flow resistance with adduction as

the parameter. For whisper, Figures 31, 33, and 35 suggest that when the male and female data

are combined, there is a general increase in the flow resistance as adduction changes from

normal to breathy to pressed, more dependent on pressure than on the adduction level. For

example the eye ball approximation slopes for flow resistances are approximately 0.4

[kPa/(L/s)]/(cm H2O) for soft whisper, 0.16 [kPa/(L/s)]/(cm H2O) for medium whisper, and 0.19

[kPa/(L/s)]/(cm H2O) for loud whisper, suggesting that flow resistance may increase with

subglottal pressure for soft, medium, and loud whisper. Furthermore, though, the CIs are

overlapping that there is little to deduce that differentiates the three adduction levels for any of

the loudness-source conditions.

For phonation, females increased flow resistance by a factor of 0.9 compared to males at each level of adduction for all three levels of loudness. For whisper, males increased flow resistance by a factor of 1.69 compared to females at each level of adduction for all three levels of loudness. The differences between flow resistances across adduction are indicated in Table 13.

Soft Whisper 8 pressed females 7

6 normal females 5

4 breathy females

3 pressed males 2

1 normal males

Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance 0 0 5 10 15 20 breathy males Pressure (cmH20)

Figure 31: Pressure vs. Flow Resistance across Adduction in Soft Whisper

Soft Phonation 6 pressed female

normal females 4

breathy females

2 pressed males

normal males

Flow Resistance [kPa/(L/s)] [kPa/(L/s)] Flow Resistance 0 0 5 10 15 20 breathy males Pressure (cmH20)

Figure 32: Pressure vs. Flow Resistance across Adduction in Soft Phonation

Medium Whisper 6 pressed female

normal females 4

Breathy females

2 pressed males

normal males

Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance 0 breathy males 0 5 10 15 20 25 Pressure (cmH20)

Figure 33: Pressure vs. Flow Resistance across Adduction in Medium Whisper

Medium Phonation 10 pressed female

8 normal females

6 breathy females

4 pressed males

2 normal males

Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance breathy males 0 0 5 10 15 20 25 Pressure (cmH20)

Figure 34: Pressure vs. Flow Resistance across Adduction in Medium Phonation 64

Loud Whisper 6 pressed female

normal females 4 breathy females

pressed males 2 normal males

breathy males 0

Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance 0 5 10 15 20 25 30 35 Pressure (cmH20)

Figure 35: Pressure vs. Flow Resistance across Adduction in Loud Whisper

Loud Phonation 14 pressed female 12 normal females 10

8 breathy females

6 pressed males

4 normal males 2 breathy males 0

Flow Resistance [kPa/(L/s)] [kPa/(L/s)] FlowResistance 0 5 10 15 20 25 30 Pressure (cmH20)

Figure 36: Pressure vs. Flow Resistance across Adduction in Loud Phonation 65

Thus, it is instructive to examine the pressure-flow and pressure- flow resistance figures,

with median and confidence intervals shown, to determine a general impression of the data. The

CIs indicating variance with these limited data sets are typically wide, and help to show trends

but it is important not to overstate the results of this study.

3.5 Values for the variables

The pressures and flows shown in Figures 13-18 and 25-30 suggest that subglottal pressure typically ranged from lows of 3-6 cm H20 to highs of 20-30 cm H20, not differing much

from figure to figure. Flow, however, did have different ranges of note across the conditions. The

shortest ranges were provided by pressed and normal phonation across loudness (about 150 to

400 cc/s), and the largest ranges for flow were provided by breathy conditions (whisper and

phonation across loudness, about 400-1700 cc/s and 400-1400 cc/s, respectively) and loud

whisper across adduction (approximately 600-1800 cc/s). The logical inference is that pressed

conditions limit the flow, breathy conditions augment the range due to larger glottal areas, and

high subglottal pressure during whisper also will generate a wide flow range. These figures also

suggest that, in general, whisper generates a wider flow range than phonation across loudness for

each adduction level, but does not generate a wider flow range between whisper and phonation at

each loudness level.

CHAPTER 4

DISCUSSION

The advantage of this project compared to other studies on whisper and phonation was the attempt to train subjects to validly produce whisper and phonation relative to nine categories of adduction (breathy, normal, and pressed) and loudness (soft, medium, and loud). This was done to understand with greater sensitivity the potential differences between whisper and phonation relative to these variables.

4.1 Subglottal pressure (Ps)

Whisper vs. Phonation: Whisper had lower predicted median Ps values compared to phonation in 15/18 treatment combinations (3 adduction x 3 loudness x 2 genders) but without a significant difference in 17/18 treatment combinations (Figure 7). The observation of lower Ps in whisper is in agreement with the literature (Arnold & Luchsinger, 1965). The lack of significant difference for Ps between whisper and phonation within the nine categories suggests a greater sensitivity than prior studies. Stathopoulous et al. (1991) reported that whispering involves lower lung volume, lower Ps, higher mean airflow, and lower flow resistance compared to phonation.

In this study, a significant difference was found only between the Ps of whisper and phonation in the breathy soft condition in females, and even that result needs consideration given the lack of a

Bonferroni-type correction to the multiple paired comparisons.

Normal adduction- medium loudness whisper: The mean Ps for normal adduction and medium loudness whisper was 5.38 cm H20 for females and 8.89 cm H20 for males. These values

are higher than those found by Stathopoulos et al. (1991) who reported a mean Ps of 4.00 cm

H20 for females and 4.61 cm H20 for males during whispering. Both the present study and the 67

study by Stathopoulos et al. (1991) used young adults (i.e., less than 28 years of age) and a similar method of measurement of intraoral pressure. However, the utterance used in the two studies was different. The present study used /baep/ strings as stimulus while Stathopoulos et al.

(1991) used /pi/ strings. Also, Stathopoulos et al. (1991) instructed their subjects to produce a

“comfortable whisper at a normal loudness and rate” while the present study asked subjects to

produce “soft, medium, and loud whisper.” The differences in utterances and instruction for whisper may have resulted in the differences of Ps found in the two studies.

Ps across loudness: The predicted median Ps for soft, medium, and loud phonation at normal adduction found in this study were 5.0, 7.0, and 11.8 cm H20, respectively, for females,

and 6.2, 9.3, and 13.2 cm H20 respectively for males. Ps values found in this study are higher

than those reported in the literature for males and females at different vocal loudness. Holmberg,

Hillman, and Perkell (1988) reported a Ps of 4.79, 6.09, and 8.46 cm H20 in females; 4.79, 5.91,

and 8.39 cm H20 in males for soft, medium, and loud phonation. While the Ps values obtained in this study for soft and medium loudness in females are similar to Holmberg et al. (1988) study, the Ps values for males in this study are higher. Higgins and Saxman (1991) estimated Ps based

on repetition of /baep/ at a rate of 3 syllables/s using a comfortable pitch at: a) comfortable

loudness, b) at approximately 6 dB below the subject’s comfortable SPL (soft), and c) at

approximately 6 dB above the subject’s comfortable SPL (loud). Higgins and Saxman (1991)

estimated a mean Ps of 4.8, 6.5, 8.8 cm H20 in young females and 4.5, 5.8, and 7.9 cm H20 in

young males respectively for soft, medium, and loud phonation. Stathopoulous and Sapienza

(1993) estimated Ps from peak intraoral pressure averaged over 7 repetitions of /pa/ at a rate of

1.5 syllables/s using a comfortable pitch at a) at a comfortable loudness, b) at 5 ±1 dB below the

comfortable level (soft) and c) at 5 ±1 dB above the comfortable level (loud). Stathopoulous and 68

Sapienza (1993) estimated a mean Ps of 3.7, 4.8, 7.7 cm H20 in females and 4.0, 5.2, and 8.1 cm

H20 in males for soft, medium, and loud phonation, respectively. Our results are closer to those

of Higgins and Saxman (1991) rather than Stathopoulous and Sapienza (1993), suggesting that

instruction, protocol, and analyses may play a large role in the values obtained for whisper and

phonation.

Ps range: Pressed loud whisper in males had the highest median Ps (24.19 cm H20)

compared to all other treatment combinations, followed by pressed loud phonation in males

(20.48 cm H20). Normal soft whisper in females had the lowest median Ps (3.46 cm H20)

followed by breathy soft whisper in females (Ps= 4.14 cm H20). These findings are similar to the

Sundberg et al. (2010) study findings. Sundberg et al. (2010) compared Ps of whisper at 3

different loudness and adduction levels and found that pressed loud whisper had the highest

mean Ps (10 cm H20) and normal (adduction) soft whisper had the lowest Ps (3 cm H20).

However, it must be noted that Sundberg et al. (2010) did not compare whisper and phonation.

The Ps range for whisper was close to that of phonation. The Ps range for phonation was

1.56 - 30.55 cm H20 and 1.54 - 32.4 cm H20 for whisper. The Ps range for whisper obtained in this study was much greater than that found in the Sundberg et al. (2010) study where they reported a Ps range of 1.3 - 17 cm H20 in whisper. Sundberg et al. (2010) instructed their subject

to whisper /p/ sequences at three loudness levels of soft, medium, and loud. In this study, the

subjects were instructed to whisper /baep/ at least 5 dB below their comfortable (medium)

loudness for soft whisper and at least 5 dB above their comfortable loudness for loud whisper.

This difference in the way vocal loudness was varied and the stimuli used in both studies may

account for the Ps range differences. 69

Sundberg et al. (2010) used only one male subject, “a tall baritone,” in their study while

the present study had 5 female and 3 male subjects. The inclusion of 8 subjects and both genders

could have resulted in the increased range of Ps. The characteristics of the subjects who

participated in this study are mentioned in Appendix I, which suggests that there were no

atypical F0 productions in their speech or other outstanding characteristics.

4.2 Airflow (F)

Whisper vs. phonation: Whisper had greater predicted median airflow than phonation in

16/18 treatment combinations (Figure 8). However, a significant difference between the airflow

for whisper and phonation was not found in the soft condition (exception: normal adduction in

females), and breathy medium and breathy loud conditions in males.

The finding that whisper generally produced more airflow than phonation was also found by Monson and Zemlin (1984) and Stathopoulous et al. (1991). The predicted median airflow range for males in this study (223 - 1693 cc/s) is wider than that found by Sundberg et al. (2010), who also studied whisper across 3 loudness and 3 adduction conditions for a single male subject.

Sundberg et al. (2010) reported a mean airflow range of 900-1710 cc/s.

In this study, female soft whisper (at normal adduction) had a predicted median flow of

338 cc/s while the mean flow of female “low intensity whisper” in the study by Monson and

Zemlin (1984) was 203 cc/s. In this study, loud whisper (at normal adduction) had a predicted

median flow of 1039 cc/s while Monson and Zemlin’s study reported a mean flow of 328 cc/s for

“forced whisper.” Thus, the flows for this study were higher by a factor of 1.6 to 3.2 for females.

It would appear that “forced whisper” may have included relatively high adduction levels in

Monson and Zemlin’s study. 70

Predicted median airflow for normal whisper (i.e., normal adduction-medium loudness)

in females and males was similar to that reported by Stathopoulous et al. (1991). Predicted

median airflow for normal whisper was 583.25 cc/s in females and 525.75 cc/s in males in this study. Stathopoulous et al. (1991) reported a mean airflow of 500 cc/s in females and 530 cc/s in males during “comfortable whisper.”

Flow range: Predicted median airflow was highest for breathy loud whisper in females

(1504 cc/s) followed by breathy loud whisper in males (1355 cc/s). Normal (adduction) loud phonation in females had the least median airflow (169 cc/s). This was contrary to the expectation that a pressed phonation would have the least mean airflow. It is possible that subjects did not close the posterior glottis but instead closed the anterior glottis only. This would have resulted in greater mean airflow compared to the normal (adduction) loud condition where both the anterior and posterior glottis is most likely in an adducted position.

For whisper, the highest airflow for males, 1355 cc/s, was for loud breathy production and the least airflow for males, 280 cc/s, was for soft pressed production. In the Sundberg et al.

(2010) study that used a “tall male baritone,” the highest mean airflow was found for breathy loud and breathy medium whisper, and lowest mean airflow was found for pressed medium whisper. Thus, the two studies are consistent for the highest flow, and “close” for the least flow in whisper.

Flow across loudness: Holmberg et al. (1988) reported a mean flow of 160, 140, and 140 cc/s in females; 230, 180, and 190 cc/s in males for soft, medium, and loud phonation, respectively. In this study, at normal adduction, mean flow was 203, 189, and 169 cc/s in females; 274, 255, 228 cc/s in males for soft, medium, and loud phonation, respectively. In both the present study and in Holmberg et al. (1988) study loud phonation had the greatest flow 71 compared to medium and soft loudness in both males and females. The flow values obtained in this study are higher than those obtained by Holmberg et al. (1988).

When adduction was normal, soft whisper had 1.6 times more airflow than soft phonation; medium whisper had approximately 3 times more airflow than medium phonation; loud whisper had 5 times more airflow than loud phonation (Figures 17-18). Higher airflow for whisper compared to phonation suggests that the constriction at the level of the glottis (and also perhaps the supraglottis) is “aerodynamically” less during whisper production. Increased glottal and supraglottal constriction have been reported in whisper by Rubin et al. (2006), Solomon et al. (1989), Tsunoda, Niimi, and Hirose (1994), and Weitzman, Sawashima, Hirose, and Ushijima

(1976).

A strong finding in this study was that, for both males and females, airflow in loud whisper was greater than soft whisper (the difference was 497 – 873 cc/s and ratios of difference between 2.38 to 3.08) across all three levels of adduction. This was likely due to the greater Ps and lower flow resistance in loud whisper compared to soft whisper at all three levels of adduction. In phonation unlike whisper, the average difference between the airflow of soft and loud phonation was only 37 cc/s for normal and pressed adduction. For breathy adduction, the flow was greater for loud phonation by 384 cc/s (averaging males and females). Greater closed quotient with increased Ps may help explain the difference of only about 37 cc/s for the normal and pressed phonations, whereas the larger and more constant glottal area for breathy phonation and the whisper conditions would require flow to increase with increase in Ps. A straight-edge vocal fold configuration is also commonly associated with whisper (Solomon et al., 1989). This configuration results in turbulence in both whisper and breathy phonation. Solomon and Markon 72

(2000) studied the translaryngeal flow, translaryngeal pressure, and laryngeal airway resistance

in young adults and found that breathy phonation was similar to whisper across all measures.

4.3 Flow resistance (Rf)

Whisper vs. Phonation: Whisper had lower flow resistance compared to phonation in

17/18 treatment combinations (Figure 9). However, a significant difference was seen only in

8/18 treatment combinations (Figure 9). In males, a significant difference between whisper and

phonation was present only for the normal adduction-loud combination. In females, a significant

difference was not present between whisper and phonation for breathy-soft and pressed-soft

conditions. The range of flow resistance in whisper was 0.18-17.39 kPa/(L/s).

Rf across loudness: For phonation, flow resistance increased as loudness increased (Table

14, Figures 20, 22, 24), for both males and females. In this study, in normal phonation, a Rf of

2.58, 3.75, and 6.6 kPa/(L/s) in females; 2.3, 3.3, and 5.9 kPa/(L/s) in males for soft, normal, and loud phonation, respectively. This finding is similar to that found by Holmberg et al. (1988).

Holmberg et al. (1988) reported a Rf of 2.9, 4.4, and 6.1 kPa/(L/s) in females; 2.07, 3.25, and

4.32 kPa/(L/s) in males for soft, normal, and loud phonation, respectively. An increase in flow resistance across loudness means that the ratio of pressure to flow increases. This can be deduced from Figures 14, 16, and 18, where pressure rises and flow decreases (Figures 14 and 18) or pressure rises faster than flow (Figure 16). The difference in flow resistance between loud and soft loudness was more pronounced for pressed [4.41 kPa/(L/s)] and normal adduction [4.03 kPa/(L/s)] compared to breathy phonation [0.4 kPa/(L/s)].

In whisper (Table 14, Figures 19, 21, and 23), however, the difference between loud and soft whisper was less pronounced [-0.52 to 0.01 kPa/(L/s)] for all 3 levels of adduction. Solomon and Markon (2000) found that flow resistance was lowest in low-effort whispering followed by 73 high-effort whisper, breathy voice, and normal voice. They studied 3 women and 3 men who repeated /pi/ at a rate of 1.5 syllables/s. The flow resistance for low effort whisper, high effort whisper, breathy voice, and normal voice was reported to be 1.163, 1.893, 2.105, and 3.848 kPa/(L/s), respectively. In this study, the flow resistance for soft whisper, loud whisper, breathy phonation, and normal phonation was 1.39, 1.26, 1.85, and 3.88 kPa/(L/s), respectively. Solomon and Markon (2000) reported means and standard deviations, but it is not known if those differences are statistically significant.

Rf across adduction: At each level of loudness, pressed adduction had the highest flow resistance followed by normal and breathy adduction for all treatment combinations for both genders (Table 17). This finding is similar to that found by Holmberg (1980) who reported that flow resistance was highest for pressed phonation and lowest for breathy phonation irrespective of intensity and fundamental frequency. Grillo, Perta, and Smith (2009) also reported the highest flow resistance for flow resistance for pressed vocal quality in untrained females when they phonated at a constant comfortable vocal intensity. They reported a mean flow resistance of 13.6,

3.2, and 1.4 kPa/(L/s) for pressed, normal, and breathy phonation respectively. In this study, the predicted medians of pressed, normal, and breathy adduction in female phonation at medium loudness was 6.10, 3.75, and 1.76 kPa/(L/s), respectively.

Of particular interest are the trends shown by the flow resistance figures (Figures 19-24).

For phonation (Figures 20, 22, 24), flow resistance increased with pressure for all 3 adductions as loudness increased. The increase is a consistent trend for both males and females. These results suggest that flow resistance increase is independent of adduction for phonation and that as loudness increases, the ratio of pressure to flow increases. 74

The trend for whisper, however, is nearly the opposite of that for phonation regarding

flow resistance. As loudness increases, the trend for flow resistance is either to decrease with

loudness (Figure 19) or stay relatively constant (Figure 21, 23), with males showing higher

values. A decreasing trend for pressed whisper means that flow increases faster than pressure

(shown in Figure 13), and a relatively constant flow resistance means pressure and flow increase

proportionally with loudness (graphed against pressure), as shown in Figures 15 and 17 for

breathy and normal whisper, respectively.

It is noted that trends of the median values, as shown in Figures 14-36 go beyond the

statistical analyses given here, and create hypotheses for relationships among variables for future

studies.

4.4. Other observations

Breathy - loud and pressed - soft phonation types were two conditions that were difficult

to produce for many subjects. The notion that it is difficult to increase loudness during breathy

adduction was also reported by Holmberg (1994). The pressed - soft condition was also difficult

to produce for the following reason - pressed adduction is produced with increased medial

compression of the vocal folds and the vocal processes of the arytenoids are adducted close to

each other. However, during the production of soft phonation there is typically incomplete glottic

closure (Rammage, Peppard, & Bless, 1992). Since the laryngeal configurations for pressed

phonation and soft phonation contrast each other, it is reasonable that subjects would have difficulty producing them, despite the training sessions.

CHAPTER 5 SUMMARY The present study compared the aerodynamic measures of estimated subglottal pressure

(Ps), glottal airflow (F), and flow resistance (Rf) of whisper and phonation. Five females and

three males whispered and phonated a series of five /baep/ syllables in nine different

combinations (3 levels of adduction x 3 levels of loudness). This resulted in 18 different

treatment combinations (i.e., 3 adductions x 3 loudness levelsx 2 genders) for whisper and

phonation. The proposed research questions, pertinent findings, and their significance are

summarized below.

Research question 1: Do subglottal pressure, glottal flow, and flow resistance differ

between phonation and whisper relative to loudness and adduction in males and females?

Salient finding 1: Subglottal pressure (Ps) did not significantly differ between whisper and phonation (except female/breathy/loud; Figure 7).

Expected finding? No. Ps for whisper was expected to be lower than that for phonation

considering that whisper has a more open glottal configuration.

Importance and relevance: The lack of Ps difference between whisper and phonation

suggests that the respiratory effort for whisper and phonation may be similar.

Can the trend be believed? Yes, as the Ps values obtained in this study appear to be valid.

Salient finding 2: Airflow (F) tends to be higher for whisper than phonation for medium and

loud conditions but about the same for the soft condition in both males and females (Figure 8).

Expected finding? Yes. The literature has reported greater airflow for whisper compared

to phonation. However, the expectation would also suggest that airflow would be greater in the

soft condition, which was not found. 76

Importance and relevance: No other study, to our knowledge, has compared whisper and

phonation at different levels of adduction and loudness. Our finding that the flow was not

significantly different for soft whisper and soft phonation has helped to refine our understanding.

That is, the finding that whisper has more airflow than phonation cannot be generalized to all

levels of loudness.

Can the trend be believed? Yes. The glottal configuration for soft phonation is most

likely more open compared to medium and loud phonation, and whisper also has a more open

glottal configuration compared to phonation. Thus, airflow for soft phonation and soft whisper

may not be greatly different. Whisper also has more airflow compared to phonation because the

closed phase in phonation reduces the airflow for phonation.

Salient finding 3: Flow resistance (Rf) tends to be greater for phonation than whisper (except for pressed adduction in males), a trend seen more for females than for males (Figure 9).

Expected finding? Yes. Whisper typically has been considered as less resistive to flow

than phonation. However, the greater trend for females was not expected.

Importance and relevance: The consistent finding that whisper has lower Rf than

phonation (except pressed adduction in males) suggests that one should expect lower Rf in

whisper regardless of level of adduction or loudness.

Can the trend be believed? Yes. Rf is derived from Ps and F (Rf= Ps/F). Since Ps is

similar for whisper and phonation but F is greater for whisper than phonation, Rf is expected to

be lower for whisper compared to phonation.

Research question 2: Do subglottal pressure, airflow, and flow resistance vary across the three loudness levels (soft, medium, and loud) for phonation and for whisper in males and females?

Salient finding 4: Ps increases with loudness for all cases of adduction for both phonation and whisper (Table 12, Figures 13-18).

Expected finding? Yes. This finding is consistent with many studies.

Importance and relevance: Ps is typically thought to be the primary mechanism controlling loudness (besides vocal tract shaping). This holds for whisper and phonation at each level of adduction (breathy, normal, pressed).

Can the trend be believed? Most likely. The literature suggests this finding that Ps increases with loudness. The median Ps values increase consistently across loudness, but these observations are qualified due to the overlapping confidence intervals.

Salient finding 5: Ps is higher in males for each of the 18 conditions (i.e., 3 loudness levelsx 3 adductions x 2 sources; Table 12, Figures 13-18).

Expected finding? Perhaps.

Importance and relevance: Given that the subjects were asked to produce utterances at soft, medium, and loud levels, it is hypothesized that source acoustics favor females relative to overall intensity, allowing lower Ps values to achieve the desired loudness levels. That is, females have higher pitch, which favors more efficient intensity production, and shorter periods which favor faster flow declination rates of the glottal flow (a measure related to overall SPL), possibly giving relatively the same loudness with less Ps.

Can the trend be believed? Yes. The median Ps values (Figures 13-18) increase consistently across loudness for all three levels of adduction. Caution must be exercised while interpreting this finding as the Ps confidence intervals overlap for males and females. 78

Salient finding 6: For whisper, flow increased with loudness ( for the 6 conditions, 3 adductions x 2 genders; Table 12, Figures 13, 15, 17)

Expected finding? Yes. This finding is consistent with the literature. Static modeling studies have also reported that for a constant orifice area, flow increases with Ps increase.

Importance and relevance: These results help to confirm that the relatively static glottal configuration in whisper acts similarly to any orifice in that increased flows are produced by increased pressures. Also, this finding helps to understand the variability in flow in whisper. I.e., if one does not consider the level of loudness produced during whisper, a large range of airflow may result.

Can the trend be believed? Yes. The findings are consistent with the literature (Monson and Zemlin, 1984; Stathopoulous et al., 1991; Sundberg et al., 2010). It is also noted that the confidence intervals for flow in whisper rarely overlapped.

Salient finding 7: For phonation, flow as a function of loudness varied relative to adduction, viz., Flow for pressed phonation: Soft > Loud ≥ Medium (Figure 14)

Flow for normal phonation: Soft > Medium > Loud (Figure 18)

Flow for breathy phonation: Loud > Medium >Soft (Figure 16)

Expected finding? Yes. Closed quotient is less for soft phonation compared to medium and loud phonations. This would result in more flow for soft compared to medium and loud phonation. Breathy phonation has a more open glottal configuration, similar to whisper, and hence the flow pattern should be similar to that for whisper.

Importance and relevance: The flow patterns for phonation are unlike those in whisper.

Hence, this is a pertinent aerodynamic difference between whisper and phonation. Three relatively distinct flow patterns for pressed, normal, and breathy adduction were present with an increase in loudness. Flows were relatively constant with a narrow range for pressed phonation, 79

flows increased and had a wider range (nearly doubling) for breathy phonation (like whisper),

and flow decreased but had a narrow range for normal phonation. Thus, adduction levels control

flow pattern with loudness increase.

Can the trend be believed? Yes, since the flow pattern was distinct for the 3 levels of

adduction in phonation.

Salient finding 8: In whisper, females had consistently greater airflow than males, a finding that was reversed in phonation, where males had greater airflow than females in all adduction cases

across loudness levels (Table 12, Figures 13-18).

Expected finding? For phonation but not for whisper. That is, for phonation, females tend

to have a smaller larynx and thus possibly less airflow especially with the lower Ps values (than

males). For whisper, the finding that females have more flow at each level of loudness,

regardless of adduction, was surprising. We hypothesize that females have a relatively enlarged

glottal area compared to males, thus allowing for an increased flow.

Importance and relevance: For whisper, females had greater flow than males across

loudness for all three levels of adduction, unlike in phonation. This suggests a gender difference

for flow in whisper and phonation both, although the trend may be considered weak due to

overlapping confidence intervals. We hypothesize that the glottal area for whisper in females is

similar to males, despite the smaller laryngeal size, a topic for future research.

Can the trend be believed? Partly. That is, although the trends are consistent, the trends

are weakened because of the overlap of confidence intervals for all the cases.

Salient finding 9: In phonation, Rf (defined by Ps/F) increased with loudness for each of

the 6 conditions (3 adductions x 2 genders). In whisper, there was no general pattern, Rf being

relatively constant for each gender 80

Expected finding? Yes. The literature suggests that Rf increases with loudness during phonation (Holmberg et al., 1988). The relatively constant flow resistance across loudness for males and females for breathy and normal whisper is a novel finding, however.

Importance and relevance: For phonation, there were two “mechanisms” that determined flow resistance, one demonstrated by breathy phonation, the other by both normal and pressed phonation. For breathy phonation, because Ps and F increased together, Rf was nearly constant

(slightly rising). However, for normal and pressed phonation, flow decreased as Ps increased, and thus Rf increased. For whisper, because Ps and F increased together (somewhat like breathy phonation), Rf remained approximately constant for breathy, normal, and pressed whisper. Those who might imagine flow resistance to be a controlling factor in laryngeal aerodynamics would want to recognize that these patterns are dependent on both the level of adduction and source

(phonation or whisper)

Can the trend be believed? The trend for phonation appears supported, but attention to the confidence intervals is important. Rf between loud and soft appears to be distinct for pressed and normal phonation because for loud and soft the confidence level bars do not overlap.

However, for breathy phonation, the median values are relatively close and the confidence levels overlap, again more like what is found for whisper. For whisper, the trend for constancy is best seen for each gender (Figures 19, 21, and 23), where the median values across soft, medium, and loud productions are surprisingly nearly the same for breathy and normal whisper. For pressed whisper, there is more variation of the median values, but still the confidence intervals overlap considerably. 81

Salient finding 10: For phonation, males and females had similar Rf values for each loudness condition, regardless of adduction level, but distinctly different Rf values in whisper, with females having lower Rf values.

Expected finding? No. It seemed that there should not have been a good reason to think

that males and females would have nearly the same value of flow resistance in phonation at any

particular adduction level, and then have different flow resistance values (females lower) during

whisper.

Importance and relevance: This observation highlights an important difference between

males and females regarding phonation and whisper. Indeed, because females tend to have a

smaller larynx compared to males, one might think that flow resistance should be consistently

higher than females for both phonation and whisper (due to the expected smaller glottal areas for

the female larynx for either phonation or whisper). However, there was no gender difference for

Rf in phonation (Figures 20, 22, and 24), and Rf was lower, not higher, for females during

whisper (Figures 19, 21, and 23). For whisper, Ps decreased with an increase in F resulting in

decreased Rf for each loudness level in females.

Can the trend be believed? Yes, upon examining the data. For example, why are the male

and female flow resistance values nearly the same for phonation for each loudness level? Figures

14, 16, and 18 indicate that females have lower pressures and lower flows than males. However,

the ratio of those pressures to flows turns out to be about the same value, giving rise to nearly the same Rf value. For whisper, on the other hand, typically because flows are about the same between females and males but males have a little higher Ps value for each loudness, the flow resistance is lower for females. 82

Research question 3: Do subglottal pressure, airflow, and flow resistance vary across the

three adduction levels (breathy, normal, and pressed) for phonation and for whisper in

males and females?

Salient finding 11: Subglottal pressure (Ps) was consistently rank-ordered, increasing from normal to breathy to pressed at each level of loudness for phonation. For whisper, Ps was nearly the same for breathy and normal adduction but was greater for pressed adduction at each level of loudness.

Expected finding? Partially. The finding that pressed adduction had the greatest Ps for

both phonation and whisper at any level of loudness is within general expectation. Pressed

sounds are typically made with higher Ps when Ps is not specifically controlled. It is surprising,

however, that for whisper, Ps was nearly the same for breathy and normal adduction at each level

of loudness instead of breathy adduction having lower Ps.

Importance and relevance: The respiratory system may have to work “harder” to produce

pressed adduction sounds for both phonation and whisper because of the higher Ps values for

pressed. Because Ps was similar for breathy and normal adduction in whisper, it implies that

breathy adduction does not necessarily require less respiratory effort than normal adduction at

any desired loudness level. For phonation, it is relevant to basic function and clinical direction

that (1) Ps is lowest for normal phonation rather than for breathy phonation, and (2) the

difference in Ps between normal and breathy adduction is similar to the difference between

breathy and pressed adduction. A lower Ps to satisfy a loudness level can be taken to be more

“efficient” because of less “work”, and to observe that breathy phonation requires greater Ps

suggests that breathy phonation is not “more efficient”, at least from a respiratory point of view.

Similarly, because the pressure is higher as well as the flow, there is greater aerodynamic power 83

(at the tracheal level) for the breathy phonation compared to the normal adduction phonation, at

the same loudness, suggesting even more “efficiency” for normal adduction.

Can the trend be believed? Yes. Further consideration suggests a reason for the higher Ps

values for breathy compared to normal adduction for phonation. The acoustic spectrum for

breathy phonation is steeper than normal phonation and therefore typically not as loud. Hence, an

increase in Ps might be used to boost the spectrum and therefore produce breathy adduction

phonation with a similar loudness level to that of normal adduction. Relative to pressed

phonation having the highest Ps values, the importance of the phonation threshold pressure

(PTP) comes into play here. Pressed phonation will have a higher PTP to get the vocal folds

vibrating, and thus there is the expectation that Ps should be higher for pressed phonation in general. For whisper, the speculation may be made that when a similar pressure is used for normal and breathy whisper, there may be an acoustic tradeoff for nearly equal loudness where the more narrow glottis for normal adduction gives a higher intensity to a narrower range of frequencies.

Salient finding 12: For phonation, the amount of flow was greatest for the breathy adduction and about the same for the pressed and normal productions. Figures 26, 28, and 30 suggest the

flows for breathy were about 3 to 4 times greater than for normal and pressed adductions, at any

loudness level.

Expected finding? Partly. Breathy flow certainly was expected to be greater than for

normal or pressed phonation, but the flow for normal phonation would be expected to be greater

than for pressed phonation.

Importance and relevance: The flow for breathy phonation was greater than for normal

and pressed even for soft phonation, and that difference increased for normal and then even more 84

for pressed phonation (Figures 26, 28, 30). The amount of difference increasing with loudness

may be a new and important finding. The flow for normal and pressed phonation being about the

same has relevance especially when one expects that the flow will be less for pressed phonation,

if that is the goal (e.g., to conserve air during phonations, a strategy necessary for long phrases).

In addition, because there is greater airflow in breathy productions, breathy production may be

more complicated in its physiology because lung volume is changing faster.

Can the trend be believed? Yes. Breathy phonation typically has consistently higher

flows than normal and pressed phonation presumably due to larger glottal areas if the subglottal

pressure is similar. The finding that normal and pressed phonations have about the same flow is

easily approached by the possibility that subjects did not close the posterior glottis. This was

perceived by the researchers on many occasions. The training included the attempt to close the

posterior glottis for pressed phonations, but this was not an easy gesture to acquire, and it was

not required.

Salient finding 13: For whisper, like for phonation, breathy productions had consistently higher airflows than for normal and pressed whispers (Table 13 and Figures 25, 27, and 29). And, like for phonation, the flows were similar for normal and pressed whispers for soft and medium loudness levels. However, unlike phonation, flow tended to be lower for pressed whisper than for normal whisper when produced loudly.

Expected finding? Partially. Similar to phonation, breathy whisper was expected to have

the greatest flow. However, the finding that normal and pressed whisper had similar flows for

soft and medium loudness whisper was not expected due to the assumption that the glottal area

would be smaller for pressed whisper. Normal whisper was expected to have greater flow than

pressed whisper. 85

Importance and relevance: The glottal flow obviously depends on the size of the glottis and the subglottal pressure, with more flow if the glottal area is greater or if the subglottal pressure is greater. The results here may lead to an estimate of glottal area depending on the amount of the flow and on the loudness, with the greatest flows pertaining to breathy whisper at each loudness level, and therefore a fairly open glottis. If whisper is used, phrase length will depend upon the airflow, being short if airflow is high. From a diagnostic point of view, measuring the flow (and subglottal pressure) will be informative regarding the glottal area being used by the client during whisper.

Can the trend be believed? Yes. Similar to phonation, breathy whisper has consistently higher flows than pressed and normal adductions. The possible explanation for the pressed whisper having similar flows to normal whisper lies in the assumption of smaller glottal area for pressed whisper and the observation (Figures 25, 27, and 29) that greater subglottal pressure values were used for pressed whisper. Thus, there may be a tradeoff between lower Ps and larger glottal area for normal whisper compared to higher Ps and smaller glottal area for pressed whisper.

Salient finding 14: Males tended to have greater flows for phonation but lower flows for whisper compared to females across adduction and at each loudness level (Table 13 and Figures

25-30).

Expected finding? Mixed. The phonation results could be expected based on male flows being higher than female flows in general. For example, Holmberg et al. (1988) showed that males had greater average airflows than females for soft and normal and loud phonations

(although this was not a study of adduction, also). However, the reasons for lower flows for 86 males for whisper at each adduction level (across loudness) is unclear. This is more surprising because the females not only have greater flow, but also less pressure.

Importance and relevance: A strength of this study is showing flows for each gender for different adduction levels, with a figure for each level of loudness (i.e., Figures 25, 27, and 29).

Thus, the variability if those parameterizations were not in place might be quite large (as one can see that flows tend to increase with loudness across those three figures). At any one level of loudness, the differences between genders show a definitive trend (males always have median values higher than females for phonation but lower for whisper), which are important suggestions here and also hypotheses for future research. What softens the observations, however, is the overlap of the confidence intervals between the genders, suggesting that their flow values, when controlling for loudness and adduction, may not be very different, if at all. If they actually are not, or if they are only minimally different, the implications for phonation theory (explaining the similar values) and clinical application (not expecting males to have higher flows).

Can the trend be believed? Partially. The trend is surprising but can be explained. The larger vocal folds and greater dynamic glottal area accompanied by higher Ps values may account for higher flows in males in phonation. For whisper, it is hypothesized that females have an enlarged glottal area compared to males and hence have greater flows, constituting an important hypothesis to be tested in future research. The gender difference, however, is qualified due to overlapping confidence intervals. Due to that observation, males and females may not actually differ as much as the median values tend to suggest. That would then be cause for deeper reasoning. 87

Salient finding 15: Flow resistance (Rf) increased from breathy to normal to pressed in all cases

(3 loudness levels and 2 genders) of phonation. For whisper, Rf for breathy and normal were similar, however.

Expected finding? Yes. As the vocal fold compression increased from breathy to pressed adduction, flow resistance was expected to increase. However, the trend for whisper where Rf for breathy and normal were found to be similar was not expected.

Importance and relevance: From this study, for phonation it is clear that Rf is dependent upon the level of adduction, increasing with greater adduction. It is highly relevant to see that this trend was the same for each loudness level (e.g., soft phonation did not change the result compared to loud phonation), so that if the flow resistance is the relevant measure clinically, for example, the expectation is for an increase with adduction at any loudness level. For whisper, however, flow resistance tends not to be different for breathy and normal whisper (although larger for pressed whisper). Again this observation is important clinically if the measure is taken to be the relevant one to consider.

Can the trend be believed? The trend for phonation is strong. Flow resistance is the ratio of pressure to flow, and that ratio is greatest for pressed phonation because the flows are relatively low with the highest pressures (Figures 26, 28, and 30). The breathy flow resistance values are lower than for normal phonation due to having the highest flows. For whisper, pressed productions have the highest flow resistance due to having the highest pressures and lowest flows (Figures 25, 27, and 29). Flow resistance for normal and breathy adductions are nearly the same for each gender due to similar ratios (breathy having slightly higher pressures and flows). 88

Salient finding 16: Males produced greater Rf than females for whisper across adduction levels.

For phonation across adduction levels, males had lower Rf values than females did, but the differences were small.

Expected finding? There was no firm expectation before the experiment, although a study

like that of Holmberg et al. (1988) indicates less flow resistance in males across loudness levels,

suggesting that that might be a generalization across adduction, also.

Importance and relevance: If flow resistance is the measure of interest, gender

differences are important relative to expectations. Females had slightly greater Rf for phonation

but lower values for whisper, an interesting if not telling distinction. Are the slightly higher Rf

values for phonation due to having smaller larynges, but lower Rf in whisper due to using a

relatively larger glottal area?

Can the trend be believed? Partially. The higher flow resistance for females for phonation

is related to the females having lower pressures and lower flows than males at each adduction

level (Figures 26, 28, and 30), but closer examination of the data suggest that the ratio for males,

with the slightly higher pressures and flows, gives essentially the same ratio, so it would be

prudent not to stress a difference between genders for flow resistance for phonation at each level of adduction (a curious finding). For whisper, however, there seems to be a distinct gender difference in flow resistance for pressed whisper, where the males’ Rf is higher (Figures 31, 33,

and 35) due to higher pressures but lower flows (Figures 25, 27, and 29).

To summarize, this study explains some of the key aerodynamic differences between

whisper and phonation. It also explores how the aerodynamic measures of subglottal pressure,

airflow, and flow resistance vary depending on the levels of loudness and adduction. While there

are some clear trends of the aerodynamic measures with changes in loudness and adduction for 89 both whisper and phonation and the gender differences, the results must be interpreted with caution as the confidence intervals of the different aerodynamic measures tend to overlap.

CHAPTER 6

CONCLUSION

The larynx can be taken as a complex mechanism for sound production which, at the

glottal level, has two rather distinct sound sources, phonation and whisper. Both of these sound

sources are capable of a wide variety of glottal configurations, aerodynamic output, and acoustic

characteristics. The loudness and quality for phonation and whisper (and pitch for phonation)

depend on the neuromuscular control of both the laryngeal and respiratory systems, and in

particular the subglottal pressure and glottal adduction. In their daily lives, people are capable of

controlling, and undoubtedly do use, a wide range of subglottal pressure (primarily to regulate

loudness) and a wide range of glottal adduction (to regulate quality in the breathy-normal-

pressed sense) for both phonation and whisper. However, no study has examined the

consequences of parameterizing both loudness and adduction at the same time to determine a

finer resolution of how the larynx (and body) works to make sounds, and with such a refinement,

the two basic laryngeal sound sources, phonation and whisper, have also therefore never been

compared.

It was the general goal of this study to examine such consequences of controlling

loudness (hypothesized essentially as subglottal pressure) and breathy-normal-pressed quality

(hypothesized essentially as glottal adduction) for both phonation and whisper. This study, then, was not a study of how variable laryngeal sound sources can be, but because the attempt was made to well control two primary production variables (loudness and adduction-quality), the study was intended to help uncover the sources of variability often seen in other studies of these laryngeal sound sources. For example, if an earlier study did not control specifically for adduction in either phonation or whisper, the pressure, flow, and flow resistance results may 91

have had a wide variability that this current study may help explain, because the current study has attempted to control for adduction and has examined the pressure, flow, and flow resistance results across those levels of adduction. Indeed, it has done so for all nine categories of three

levels of adduction (in the sense of producing breathy, normal, and pressed phonations and

whispers) and three levels of loudness (soft, medium, and loud), as well as for both males and

females.

The purpose of this study was to compare the aerodynamic measures of subglottal

pressure (Ps), airflow (F), and flow resistance (Rf) between whisper and phonation. Five young

adult females and three young adult male subjects were trained to produce nine categories of

phonation and whisper, namely at 3 levels of loudness (soft, medium, and loud) and 3 levels of

adduction (breathy, normal, and pressed). This resulted in 18 treatment combinations (3

adductions x 3 loudness x 2 genders). Approximately five tokens of each condition were

analyzed for each subject.

The primary aerodynamic and gender findings of this study are the following:

1. Aerodynamic differences between whisper and phonation across the 9 conditions

1.1 Subglottal pressure did not significantly differ between whisper and phonation at each

of the 9 conditions for each gender group (with one exception).

1.2. Airflow tended to be higher for whisper than phonation except when loudness was

soft.

1.3. Flow resistance tended to be greater for phonation than whisper, a trend seen more

strongly for females than males.

2. Aerodynamic results across loudness (soft, medium, loud)

2.1. Subglottal pressure tended to increase with loudness for all cases of adduction for both whisper and phonation.

2.2. Flow increased with loudness for whisper and breathy phonation.

2.3. However, the greatest flow in normal and pressed phonation was for the soft condition.

2.4. Flow resistance increased with loudness for phonation, but no general pattern was present for whisper, being relatively constant for each gender.

3. Aerodynamic results across adduction (breathy, normal, pressed)

3.1. For phonation, subglottal pressure increased from normal to breathy to pressed at each loudness level (not breathy to normal to pressed).

3.2. For whisper, subglottal pressure was about the same for normal and breathy productions, and greater for pressed, at each loudness level.

3.3. For phonation, flow was greatest for breathy productions, and about the same for normal and pressed (and considerably less than for breathy productions).

3.4. For whisper, flows were also greatest for breathy productions, and about the same for normal and pressed, for soft and medium loudness levels. For loud whispers, flow tended to be lower for pressed whisper than for normal whisper.

3.5. Flow resistance increased from breathy to normal to pressed in all cases of loudness for both genders. For whisper, flow resistance was similar for breathy and normal productions, however.

4. Gender differences

4.1. Subglottal pressure tended to be higher in males for each of the 9 conditions for both

whisper and phonation.

4.2. Compared to females, males tended to have greater flows for phonation but lower flows for whisper across adduction and at each loudness level. This observation is most obvious when comparing males and females at any chosen value of subglottal pressure.

4.3. Compared to females, males produced greater flow resistance for whisper across adduction levels (breathy, normal, pressed). For phonation across adduction levels, males had lower flow resistance values than females (but the differences were small).

4.4. Flow resistance was similar for males and females in phonation for each loudness condition (for each adduction level), but males and females had different flow resistance values in whisper, with females having lower Rf values.

The consequences of (1) a refined research design in the sense of having subjects produce nine different categories of adduction and loudness for both phonation and whisper, (2) having only 3 male and 5 female subjects who repeated tasks 5 times each (and thus creating a usable but not exceptionally large data set), and (3) the use of a powerful regression model that permits comparison among subcategories of data but with a restricted confidence level when considering all comparisons, is the following: The trends of the data from this study appear to have importance and can be constructively interpreted relative to adduction, loudness, gender, and source (phonation and whisper), but the general level of confidence may be such that the trends are best thought of as testable hypotheses for future studies.

To conclude, this study helped to explore aerodynamic phenomena of whisper and phonation when using nine distinct categories of loudness and adduction, for both males and 94 females. The findings from this study provided a refined understanding of the trends in the aerodynamic measures of subglottal pressure, laryngeal airflow, and laryngeal flow resistance for both whisper and phonation across adduction (breathy, normal, pressed) and loudness (soft, medium, and loud). Specifically, the variability in these measures can be better understood when one controls for loudness and adduction.

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105

APPENDIX I

Table A1. Physical Characteristics of Subjects

Subject Age Gender Height Weight Fo (Hz) (years) (cms) (pounds)

1 26 Male 155 170 123

2 27 Female 174 150 203

3 26 Female 171 135 204

4 22 Female 168 115 200

5 20 Male 155 180 130

6 23 Female 168 170 216

7 21 Female 158 140 226

8 22 Male 168 135 166

106

APPENDIX II

FLOW MASK CALIBRATION

Purpose

The purpose was to calibrate a large aerodynamic flow mask (Glottal

Enterprises – MSIF 2 S/N 2049S).

Equipment

The equipment used for this purpose consisted of a) a sweeper (Simplicity, Model

S14CL) to generate airflows, b) a calibrated pneumotach (Rudolph 3788), c) a pressure transducer (Glottal Enterprises PTW P116), d) two voltmeters, e) a Glottal Enterprises large flow mask (MSIF-2 S/N 2049S), and f) a mold that the flow mask fits onto. A schematic of the arrangement is shown below (Figure A1).

Figure A1: Flow Calibration of Pneumotach Mask

107

Equipment settings

The settings on the validyne pressure transducer system were as follows.

Sensitivity Gain: 15mV/V

Sensitivity vernier: 5 %

Filter: 10Hz

Suppression: off

R Balance range: High

The R balance on the zero balance and the zeroing knob on the GE pressure transducer were

adjusted until the voltmeter read zero.

Procedure

The equipment was set as shown in the schematic above. A two-way sweeper that can

push or pull air was used. Air was forced away from the sweeper through a calibrated Rudolph

pneumotach and then through the mold into the flow mask. The amount of airflow was

controlled by a line valve and a bleed valve between the sweeper and the pneumotach. The

amount of flow through the pneumotach corresponded to the voltage output of pressure

transducer-1 (Validyne MP45) - see Voltmeter-1 in the schematic of Figure A1. The amount of pressure drop across the mask, which related linearly to the flow through the mask (Glottal

Enterprises – MSIF 2), corresponded to the voltage shown on Voltmeter-2. The amount of airflow from the sweeper was manually adjusted in such a way that the voltage increments of approximately 0.5 volts were made between 0 and 4.5 volts. The voltage readings were noted simultaneously from the two voltmeters. The same procedure was repeated with the air reversed, that is, pulled through the mask in the other direction (toward the sweeper) in the ingressive 108

direction using the suction end of the sweeper. The voltage values were again noted from the two

voltmeters simultaneously.

The data are shown in Table A2. Figure A2 shows the flow mask voltage (volts) on the

abscissa and the flow (cm3/s) on the ordinate. A best-fit line was constructed and the slope and regression values were obtained. The equation that was used to convert the voltage to pressure was pressure P = 4.9295*V + 0.823. The equation to convert the mask system voltage was Flow

F=68.794*V - 2.6773, F in L/min (F= 1146.5*V - 44.621, F in cc/s). The obtained flow is in

L/min and is converted into cm3/s.

Table A2. Data for Glottal Enterprises Flow Mask Calibration

Temp: 75.2 (beg.) - 76.1(end) Humidity: 22% Pressure: 29.56 in Hg Voltage from Voltage from GE Pneumotach Flow (L/min) Flow (cc/s) Box -0.0001 0 3.1395 52.325 0.001 0 -0.9547 0.9548 39.6434136 660.714012 0.593 0.592 -2.0249 2.025 80.5593 1342.63475 1.21 1.209 -3.0803 3.0804 120.9093528 2015.125076 1.772 1.771 -3.9478 3.9479 154.0756128 2567.887401 2.311 2.31 -4.915 4.9151 191.0536032 3184.177569 2.894 2.893 -5.923 5.9231 229.5914592 3826.465089 3.413 3.412 -7.048 7.0481 272.6024592 4543.303839 3.985 3.984 0.0009 0 -0.002 0.9941 0.9932 -41.1115224 -685.182108 -0.595 -0.593 2.0617 2.0608 -81.9280056 -1365.446152 -1.201 -1.199 3.0508 3.0499 -119.7432768 -1995.690781 -1.721 -1.719 3.8692 3.8683 -151.0323456 -2517.167077 -2.185 -2.183 5.0067 5.0058 -194.5212456 -3241.970702 -2.761 -2.759 5.929 5.9281 -229.7826192 -3829.651039 -3.271 -3.269 6.81 6.8091 -263.4650112 -4391.015429 -3.722 -3.72 7.116 7.1151 -275.1640032

109

Calibration of GE Flow mask

5000 4000 3000 2000

1000 0 -5 -4 -3 -2 -1 0 1 2 3 4 5

Flow (cc/s) -1000 -2000 y = 1146.5x - 44.621 -3000 R² = 0.9997 -4000 -5000 Voltage from GE Box

Figure A2. Flow Mask Voltage vs. Flow Volume for GE MSIF-2 Mask Calibration

PNEUMOTACH MASK: ORAL PRESSURE CALIBRATION

Purpose

The purpose was to calibrate the oral pressure transducer (PTL 116) of the GE flow

mask.

Equipment

The equipment used for this purpose was a) a GE MSIF Pressure transducer (PTL116), b)

a Pressure Chamber, c) a DATA 6000 digital oscilloscope, d) a voltmeter, and e) a U-tube manometer. The equipment was connected as shown in the schematic Figure A3.

110

GE MSIF 2 Transducer Pressure chamber

DATA 6000

Voltmeter

Manometer

Figure A3. Set up for Calibration of Oral Pressure Transducer

Procedure

The pressure transducer was connected to a customized pressure chamber and a Dwyer

Flex-tube manometer. A digital oscilloscope (DATA 6000) was connected to the transducer. The pressure induced in the chamber created an equal amount of pressure in both the transducer and the manometer. The chamber can induce positive or negative pressure. The voltage and manometer readings were recorded for each pressure setting in the chamber. This procedure was followed until the output voltage reached the above mentioned saturation points (which occurred before the upper limit of the pressure transducer itself). An equation between voltage and pressure was obtained for these data, viz., Oral pressure P = 4.8909*V + 0.6209, R2 = 0.9996.

The data are given in Table A3 and Figure A4.

111

Table A3. Oral Pressure Calibration for GE Aerodynamic Flow Mask through Pressure

Transducer (PTL 116)

Manometer Manometer Zeroed Left Right Pressure Pressure Voltage Voltage (mmH20) (mmH20) (mmH20) (cmH20) (V) (V) 0 -0.5 0.5 0.05 -0.0082 0 23.5 -24 47 4.7 0.9598 0.968 35.5 -35 70 7 1.4346 1.4428 59 -59 117.5 11.75 2.381 2.3892 74 -74 147.5 14.75 3.0047 3.0129 94 -94 187.5 18.75 3.802 3.8102 120.5 -122 242 24.2 4.8926 4.9008 140 -142 281.5 28.15 5.673 5.6812 160 -162 321.5 32.15 6.432 6.4402 181 -184 364.5 36.45 7.24 7.2482 205 -208 412.5 41.25 8.171 8.1792 220 -224 443.5 44.35 8.747 8.7552 243.5 -248 491 49.1 9.599 9.6072 Zero -1 -1 0 0 0.007 0 -17 15.5 -32.5 -3.25 -0.68 -0.687 -41 40 -81 -8.1 -1.6952 -1.7022 -55 54 -109 -10.9 -2.2967 -2.3037 -76 74 -150 -15 -3.1262 -3.1332 -108 107.5 -215.5 -21.55 -4.5303 -4.5373 -115 114 -229 -22.9 -4.8176 -4.8246 -136 134 -270 -27 -5.672 -5.679 -168 164 -332 -33.2 -7.04 -7.047 -179.5 177 -356.5 -35.65 -7.499 -7.506 -205 202 -407 -40.7 -8.575 -8.582 -218 215 -433 -43.3 -9.131 -9.138 -234 232 -466 -46.6 -9.669 -9.676

112

GE Mask Oral Pressure Trandsucer Calibration 60

0 -10 -5 0 5 10

Pressure in cmH20 in Pressure -20 y = 4.8909x + 0.6209 R² = 0.9996 -40

-60 Voltage from GE Box

Figure A4. Flow Mask Voltage vs. Oral Pressure for GE MSIF-2 Mask Calibration

113

APPENDIX III

SCATTERPLOTS OF PRESSURE VS. FLOW BY SUBJECT

Scatterplot of Pressure Vs. Flow for Subject 1

0 10 20 30 -1 0 Loudness Source 3000 S W

S P ) 2000 s M W /

c M P

c 1000

( L W

L P w o

l 0 f

r 1 i

A 3000

l a t

t 2000 o l G 1000

0 0 10 20 30 Subglottal Pressure (cmH20) Panel variable: Adduction (-1=Breathy; 0=Normal; 1=Pressed) Loudness: S=Soft; M=Medium; L=Loud Source: W=Whisper; P=Phonation FIGURE A5: Scatterplot of Pressure vs. Flow in Subject 1 114

Scatterplot of Pressure Vs. Flow for Subject 2

0 10 20 30 -1 0 Loudness Source 3000 S W

S P ) 2000 s M W /

c M P

c 1000

( L W

L P w o

l 0 f

r 1 i

A 3000

l a t

t 2000 o l G 1000

115

Scatterplot of Pressure vs. Flow for Subject 3

0 10 20 30 -1 0 Loudness Source 3000 S W

S P ) 2000 s M W /

c M P

c 1000

( L W

L P w o

l 0 f

r 1 i

A 3000

l a t

t 2000 o l G 1000

116

Scatterplot of Pressure vs. Flow for Subject 4

0 10 20 30 -1 0 Loudness Source 3000 S W

S P ) 2000 s M W /

c M P

c 1000

( L W

L P w o

l 0 f

r 1 i

A 3000

l a t

t 2000 o l G 1000

117

Scatterplot of Pressure vs. Flow for Subject 5

0 10 20 30 -1 0 Loudness Source 3000 S W

S P ) 2000 s M W /

c M P

c 1000

( L W

L P w o

l 0 f

r 1 i

A 3000

l a t

t 2000 o l G 1000

0 0 10 20 30 Subglottal Pressure (cmH20) Panel variable: Adduction (-1=Pressed; 0=Normal; 1=Breathy) Loudness: S=Soft; M=Medium; L=Loud Source: W=Whisper; P=Phonation FIGURE A9: Scatterplot of Pressure vs. Flow in Subject 5

118

Scatterplot of Pressure vs. Flow for Subject 6

0 10 20 30 -1 0 Loudness Source 3000 S W

S P ) 2000 s M W /

c M P

c 1000

( L W

L P w o

l 0 f

r 1 i

A 3000

l a t

t 2000 o l G 1000

119

Scatterplot of Pressure vs. Flow for Subject 7

0 10 20 30 -1 0 Loudness Source 3000 S W

S P ) 2000 s M W /

c M P

c 1000

( L W

L P w o

l 0 f

r 1 i

A 3000

l a t

t 2000 o l G 1000

120

Scatterplot of Pressure vs. Flow for Subject 8

0 10 20 30

-1 0 Loudness Source 3000 S W S P )

s 2000 M W /

c M P c

( 1000 L W

w L P o l 0 f r

i 1 A

3000 l a t

t 2000 o l G 1000

121

APPENDIX 1V