SST 2010

Phonation in Sumi Nasals

Tom Harris1

1 School of Languages and Linguistics, University of Melbourne, Australia [email protected]

Abstract 2. Background A key feature of Sumi phonology is a distinctive Sreedhar [7, 8] identified two phonemically distinct forms of breathy/modal voicing contrast in its bilabial and alveolar the bilabial nasal and the alveolar nasal in Sumi. These nasals. Using contrastive on nasals is rare cross- distinct forms he labeled unaspirated and aspirated voiced linguistically, but relatively common in Tibeto-Burman forms, and suggested they exist as a phonemicised sequence languages. Research using instrumental techniques to provide of the nasal in question and the glottal //. In this detailed descriptions of the articulatory and acoustic paper, this distinction is labeled a breathy/modal one, and the properties of breathy nasals in Tibeto-Burman languages is nasals investigated are transcribed as /m/, /mh/, /n/ and /nh/. limited. In this study, breathy nasals were investigated using Here 'breathy' refers to the characteristic of having 'breathy a combination of airflow and laryngographic analyses. They ', known also as 'murmur' [9] or as 'voiced aspiration' were found to comprise an initial, ‘non-breathy’ segment, and [4]. A velar nasal also exists in Sumi, although a a following ‘breathy’ segment demonstrating increased breathy/modal contrast is not made at this place of airflow and voicing patterns typical of breathy voice. articulation. Sreedhar [7, 8] also posits an allophonic variant Index Terms: phonation, breathy voice, Tibeto-Burman, of the alveolar nasal, being a palatal nasal existing before articulatory front . It is suggested that this variant has a breathy/modal contrast, however, remarkably few examples 1. Introduction of either breathy or modal palatal nasals existed in the data Sumi, also known as Sema, is a language of central and south recorded for this experiment, and it appears that the palatal Nagaland, India. A language of the Naga group of the Tibeto- nasals and alveolar nasals are in free variation. Burman family, Sumi is spoken by approximately 242,000 Breathy voice refers to one of only three manners people [1]. of phonation that are known to contrast meaningfully cross- A key feature of Sumi phonology is a distinctive linguistically. These three are: breathy, modal and creaky breathy/modal voicing contrast in its bilabial and alveolar voice, of which modal is the neutral setting to which the nasals. Cross-linguistically, languages with contrasting others are compared [10]. In Sumi, there appears to be a breathy and modal voiced sounds are rare, but those that phonemic contrast between breathy and modal settings. make such a contrast do so in stops, nasals, laterals and In modal phonation, there is 'regular, efficient vowels [2]. , for example, makes a four-way voicing vibration of the true vocal folds, without audible friction' [11] distinction in its stops, labeled 'voiceless unaspirated', (p.114). Tension is a factor in determining the vibration of 'voiceless aspirated', 'voiced' and 'voiced aspirated', the last of the vocal folds - modal phonation is typified by vocal folds these being known also as breathy voiced stops. The most having 'normal adductive and longitudinal tension' which distinctive breathy characteristic of Hindi breathy stops is the results in the vocal folds being apart for half of the glottal persisting voicing throughout the segment, with a greater cycle [10] (p.15). than expected increase in airflow immediately after the Variation from this setting is known as non-modal release of the stop [2]. phonation, of which breathy voice is one form. In breathy Gordon and Ladefoged [3] suggest that Hindi voice, the vocal folds are typically more abducted than in likewise makes a breathy contrast in its nasals, although it and have less longitudinal tension [3]. This should be noted that Esposito et al. [4] state that it is not clear results in less contact between the vocal folds and therefore a if /N/ + /h/ sequences in Hindi are in fact breathy nasals, or greater volume of turbulent airflow passing through the simply [Nh] clusters. Tibeto-Burman languages, such as glottis. The vocal folds 'flapping in the breeze' [11] (p.418), Sumi, also often contrast breathy voice in their nasal sounds. coupled with their continued vibration, gives the impression An example of this is in Newar, where a two-way of 'voice mixed in with breath' (Catford, in [3] (p.385)). breathy/modal contrast exists in the nasal series [5]. The The defining articulatory characteristic of breathy Khonoma dialect of Angami – a neighbouring language of voice, then, is the manner in which the vocal folds are held Sumi – similarly makes a two-way voicing contrast in its far more loosely than in modal voice. This leads to the vocal nasals [6], and although this is a voiceless/voiced contrast folds being open for a longer portion of the glottal cycle, and rather than a breathy voiced/modal voiced contrast, the making less complete contact on closure. The proportion of airflow and timing characteristic are very similar to those in the glottal cycle that the vocal folds are apart is known as the the breathy voiced/modal voiced contrast found in Sumi. Open Quotient [12], which can be determined by analysing This paper uses a combination of acoustic and the Lx signal from a laryngograph, a device that monitors articulatory measures to establish that the breathy/modal glottal activity non-invasively by measuring glottal voicing distinction in Sumi is characterized by differences in impedance [13]. By analysing the Lx waveform, it is possible duration, airflow and glottal state. In particular, it is shown to determine for what portion of the glottal cycle the vocal that breathy nasals are typified by an increased duration and a folds are apart, and how firm the contact between the vocal sharp rise in total airflow, culminating in a peak following folds is on contact. The shape of the Lx waveform is also of the release of the nasal stop constriction.

ISBN 978-0-9581946-3-1 © 2010 ASSTA Accepted after peer review of full paper 22 14-16 December 2010, Melbourne, Australia use when analysing phonation type, as it is expected to be of repetitions of a single token, was saved individually in a more sinusoidal shape for breathy voice [14]. PCQuirer, and then exported to the Emu Speech Database The greater amount of turbulent airflow expected Management System (Version 2.2.3; [19]; henceforth with breathy voice [12] is a feature that can be measured ‘Emu’). using aerometry. Given a comparable subglottal air pressure, In total, allowing for corrupt recordings and it is expected that breathy voice will allow a greater volume impromptu amendments to the wordlist by the speaker, the of airflow to reach the oral and nasal cavities, and this can be acoustic and articulatory signals of 211 tokens, were measured using airflow masks. This method was also a key in recorded. Segmentation based on the acoustic signal was determining the articulatory correlates of breathy voice in performed using Praat [20] and Emu prior to either acoustic Sumi. It has been demonstrated by Ladefoged [15] and used or articulatory analyses due to a preliminary spectrographic by Bhaskararao and Ladefoged [6] and Blankenship et al. inspection of breathy nasals in Sumi suggesting clearly [16] to identify voiceless nasals in Burmese and Khonoma distinct composite segments to breathy . Angami, for example - both languages of the same family as The four nasals analysed in this paper were referred Sumi. to as /m/, /n/, /mh/ and /nh/, where the first two of these are modal nasals and the last two are breathy nasals. The 3. Methodology composite segments of the breathy nasals were analysed, and these were referred to as, for example, [m] in /mh/ and [h] in /mh/. After completion of labelling, the acoustic and 3.1. Speakers articulatory data was queried using the Emu-R software The research was carried out in the Phonetics Laboratory at environment [21, 22]. the University of Melbourne. Potential speakers were There was evidence of breathy segments being therefore required to be from the local area, which articulated in modal voice in some tokens. For example, in an consequently limited the number and variety of Sumi isolated speech utterance containing five tokens, breathy speakers available. One female Sumi speaker participated in voice was apparent in all but one token. It was clear from this research. She was aged in the mid-30s and was a spectral analysis that this single token contained a competent speaker of English as a second language. She was prototypical modal nasal, while the remaining four displayed a native Sumi speaker, raised in Nagaland with Sumi- the expected patterning for a breathy nasal. These anomalous speaking parents. The speaker had worked as a language tokens were analysed as modal nasals, which led to an consultant in the past. imbalance in the number of breathy and modal nasal tokens. In a number of utterances where breathy nasal tokens were 3.2. Materials anticipated, none were present in either connected or isolated speech. This was identified by the speaker as an issue with A wordlist was compiled using an English-Sumi dictionary the orthographic representation in the dictionary used for [17] and the grammar and phonetic reader of Sumi, both by compiling the word list. This further led to an uneven number Sreedhar [7, 8]. It was designed to incorporate all phonetic of breathy and modal nasal tokens. environments in which both the breathy and modal nasals existed in contrastive distribution, creating a list of words 4. Results containing these nasals in (at least near) minimal pairs. As Bradley [18] suggests, there is often some Spectrographic analysis showed that the initial, non-breathy correlation between and phonation in Tibeto-Burman portion of breathy nasals – that portion equating to, for languages. There is, however, limited literature on the effect example, [m] in /mh/ – shows similar spectrographic of tone on articulation in Sumi. Therefore, only patterning to the modal /m/. Likewise, the breathy portion, words that contained level tone were included in this study to for example [h] in /mh/, has very distinctive properties. These minimise the influence of tone. The following carrier phrase are, namely, the presence of voicing with a weak, but was suggested by the speaker, into which each of the words identifiable, formant structure with formant frequencies could be realistically inserted: similar to those of the following . It was also observed that breathy nasals were noye ___ ipi pi ani 'you are saying ___' considerably longer than modal nasals, as shown in Figure 1. Given that, on average, breathy nasals were 94.4ms longer Given that the nasals in question were never found than their modal counterparts, and the mean duration of all word-finally, and the final vowel of noye takes a level tone, breathy [h] segments was 92.1ms, the increased duration of this carrier phrase allowed all nasals to be recorded in a level breathy nasals can be attributed to the breathy [h] segment. tone environment, whether as isolated words or in connected Airflow analyses were performed on the breathy speech. and modal nasals. To take into account that any transglottal airflow is realized both as nasal and oral airflow in nasals, 3.3. Experimental Design ‘total airflow’ was measured by summing the airflow recorded from both the nasal and the oral face masks. As is A set of recordings was made in which the speaker was asked shown in Figures 2 and 3, the breathy nasals were typified by to repeat a series of words, first five times in isolation, and a steep increase in total airflow, culminating in a peak then three times in the carrier phrase. While making these occurring shortly after the onset of the breathy [h] segment. recordings, the speaker wore a split oral and nasal airflow There was anticipatory increase in total airflow during the mask that simultaneously recorded oral airflow, nasal initial non-breathy nasal portion. Figures 2 and 3 also airflow, oral pressure and an acoustic signal. An Lx signal demonstrate how the modal bilabial and alveolar nasals have was recorded from a laryngograph. All equipment was quite different airflow profiles from each other. calibrated prior to the recordings, as outlined by Ladefoged [15]. The recording equipment interfaced with a PC using PCQuirer from Scicon. Each utterance, consisting of all

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Figure 1: Mean durations (ms) of modal and breathy nasals (/m/: N=74, /n/: N=95, /mh/: N=25, /nh/: Figure 2: Mean total airflow (units) in modal and N=17) breathy bilabial nasals (/m/: N=74, /mh/: N=25)

Mean rate of Mean rate of change of Total change of Total Airflow to mid- Nasal Airflow in initial point of breathy non-breathy [h] portion portion (units/ms) (units/ms) /mh/ 22.89 79.06 /nh/ 5.50 69.45 t = 3.18, t = 0.64, t-test (10) (19) p = 0.009 p = 0.533 Table 1. Mean rate of change of total airflow in the initial non-breathy portion, and the breathy [h] segment, of breathy nasals

The modal bilabial nasal shows an increase in total airflow throughout its duration, while the modal alveolar nasal has almost constant airflow throughout. The same pattern was observed for the initial non-breathy portions of the breathy nasals, with the exception of the brief period of anticipatory Figure 3: Mean total airflow (units) in modal and increase in oral airflow near to their conclusions. The airflow breathy alveolar nasals (/n/: N=95, /nh/: N=17) profiles for the breathy [h] segments in both the breathy alveolar and breathy bilabial nasals are much more similar. Analysis of the Lx signal from the laryngograph provided This was confirmed by comparing the rate of change of total further evidence of the difference between the initial non- airflow during both the initial non-breathy portions and the breathy portion of the breathy nasals and the breathy [h] first half of the breathy [h] segment in both the alveolar and segment. It was observed that, for all breathy nasals, a period bilabial breathy nasals. The results of t-tests confirmed that of distinctive voicing was associated with the breathy [h] there was a significant difference in rate of change of total segment. This period was apparent as a low-amplitude, airflow during the non-breathy portions of the two breathy sinusoidal waveform that persisted for the duration of each nasals, while there was no significant difference in the rate or [h] segment. It was also observed that in the majority of cases change of total airflow during the breathy [h] segments of there was anticipation of this change in voice quality in the either breathy nasal. These results are summarized in Table 1 preceding non-breathy portion of the breathy nasals, with the above, and suggest that the airflow characteristics that onset occurring between 20 and 30ms prior to the start of the differentiate each nasal by occur in the breathy [h] segment. An analysis of the Open Quotient values initial, non-breathy portion, while the airflow characteristics in single examples of each of the modal nasals and each of marking a nasal as ‘breathy’ occur in the breathy [h] the breathy and non-breathy components of breathy nasals segment. showed that, although the Sumi speaker generally showed a large degree of creak in her speech, both the initial non- breathy portion and the breathy [h] segment in breathy nasals showed a more breathy Open Quotient value than the modal nasals – that is, the vocal folds were held apart for a greater percentage of the cycle. These results are shown in Table 2.

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Certainly, the airflow characteristics of all Sumi breathy Mean Closed Mean Open Mean nasals are similar to those proposed by Ladefoged and Phase Phase Segment Open Maddieson [2] for Hindi breathy (voiced aspirated) stops - Amplitude Amplitude Quotient namely a large increase in airflow immediately after the (units) (units) release of the stop. /m/ in 6317 2707 0.29 The study found that bilabial and alveolar nasals in mo Sumi have two phonemically distinct forms that differ [m] in 4699 2014 0.43 phonetically in a very interesting fashion, typified by changes mho to duration, glottal state and airflow. Further research with a [h] in 1516 650 0.36 larger sample is required to further determine whether the mho sequence of nasal + [h] sequences in Sumi can best be /n/ in 6104 2616 0.15 analysed as voiced aspirated segments, or a cluster of nasal + ana /h/, as per Esposito et al. [4]. [n] in 4450 1907 0.28 anha [h] in 2309 990 0.43 6. References anha

Table 2. Mean amplitudes of the Lx waveform and [1] M. P. Lewis, "Ethnologue: Languages of the World," Dallas: Open Quotient values for examples of modal and SIL International, 2009. breathy nasals [2] P. Ladefoged and I. Maddieson, The Sounds of the World's Languages. Oxford: Blackwell, 1996. [3] M. Gordon and P. Ladefoged, "Phonation Types: a Cross- Linguistic Overview," Journal of Phonetics, vol. 29, pp. 383- 406, 2001. 5. Discussion [4] C. M. Esposito, S. u. D. Khan, and A. Hurst, "Breathy Nasals and /Nh/ Clusters in Bengali, Hindi and Marathi," UCLA The most notable in the results is that breathy nasals consist Working Papers in Phonetics, vol. 104, pp. 82-106, 2005. of two distinct segments, the first bearing similarity to a [5] A. Hale and K. P. Shrestha, Newar (Nepal Bhasa). Muenchen: modal nasal of the same place and , the LINCOM, 2006. second being a distinctly breathy segment. This was shown in [6] P. Bhaskararao and P. Ladefoged, "Two Types of Voiceless the duration analysis in which breathy nasals were uniformly Nasals," Journal of the International Phonetic Association, vol. longer than modal nasals, with the increased duration 21, pp. 80-88, 1991. attributed to the breathy [h] segment. This finding is [7] M. V. Sreedhar, Sema Phonetic Reader. Mysore: Central Institute of Indian Languages, 1976. consistent with the duration results of Esposito et al.'s [4] [8] M. V. Sreedhar, A Sema grammar. Mysore: Central Institute of study of nasal + /h/ sequences in Bengali and Hindi. In their Indian Languages, 1980. study, /Nh/ sequences were consistently longer than /N/ [9] P. Ladefoged, A Course in Phonetics, 4th ed. Boston: Heinle segments alone, and this increase was attributed to a segment and Heinle, 2001. labeled 'breathy/aspirated' [4]. [10] C. M. Esposito, "Santa Ana Del Valle Zapotec Phonation." The nasal + [h] sequence found in Sumi, though, is MA: University of California, Los Angeles, 2003. different from other examples of breathy nasals. In Newar, [11] . Laver, Principles of Phonetics. Cambridge: Cambridge for example, breathy nasals exist as a segment of similar University Press, 1994. [12] K. Johnson, Acoustic and , 2nd ed. Malden: duration to modal nasals, but display a number of distinctly Blackwell, 2003. breathy characteristics, in particular the presence of some [13] E. R. M. Abberton, "Some Laryngographic Data for Korean high frequency noise visible in the spectrogram [3]. In Sumi, Stops," Journal of the International Phonetic Association, vol. though, the initial, non-breathy segment in the breathy 2, pp. 67-78, 1972. sonorants tended to display very few distinctly breathy [14] R. Wayland and A. Jongman, "Acoustic correlates of breathy characteristics. However, while displaying many acoustic and and clear vowels: The case of Khmer," Journal of Phonetics, articulatory similarities to modal nasals, this initial segment vol. 31, pp. 181-201, 2003. could be distinguished from a modal nasal by observing the [15] P. Ladefoged, Phonetic Data Analysis. Malden: Blackwell, 2003. anticipatory acoustic and articulatory gestures prior to the [16] B. Blankenship, P. Ladefoged, P. Bhaskararao, and N. Chase, onset of the breathy [h] segment. In particular, there was "Phonetic Structure of Khonoma Angami," Linguistics of the partial devoicing in the latter stages of the initial, non-breathy Tibeto-Burman Area, vol. 16, pp. 69-88, 1993. segment of breathy nasals, which led to increased total [17] S. Swu and H. Yepthomi, "Anglo-Sümi Tsashe (Anglo-Sümi airflow that continued into the following [h] segment where it Dictionary)," 2nd ed: Published by the Authors, 2004. culminated in an airflow peak. [18] D. Bradley, " in Burmese," Pacific Linguistics Series The characteristics of breathy nasals reported in A: Occasional Papers, vol. 62, pp. 117-132, 1982. this study bear comparison to the work of Bhaskararao and [19] S. Cassidy and J. Harrington, "Multi-Level Annotation in the Emu Speech Database Management System," Speech Ladefoged [6] on Khonoma Angami in which the absence of Communication, vol. 33, pp. 61-77, 2001. voicing reported throughout the voiceless nasals coupled with [20] P. Boersma, "Praat, a System for Doing Phonetics By the distinctive airflow led the authors to label them 'voiceless Computer," Glot International, vol. 5, pp. 341-345, 2001. aspirated nasals' (p.87). In Sumi, voicing persists throughout [21] J. Harrington, "Emu: Interface to the Emu Speech Database the entire breathy nasal, while the airflow pattern is almost System," [Computer program: Version 2.3.0], 2008. identical to that shown for Angami. This suggests that, by [22] R. Ihaka and R. Gentleman, "R: A Language for Data Analysis extension of Bhaskararao and Ladefoged's analysis, Sumi and Graphics," Journal of Computational and Graphical breathy nasals could be labeled 'voiced aspirated nasals'. Statistics, vol. 5, pp. 299-314, 1996.

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