Models of Vocal Tract Configuration for Sung Primary Vowels
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TMUS 8329: Forming Formants 1 Forming Formants: Models of Vocal Tract Configuration for Sung Primary Vowels Angerhofer, Thomas Erik University of Colorado Boulder Author Note TMUS 8329 Pedagogy Project for DMA in Voice Performance and Pedagogy TMUS 8329: Forming Formants 2 Abstract The familiar adage from the old Italian school of singing, “si canta come si parla,” or “one sings as one speaks,” is as familiar today to teachers of singing as it was in centuries past. There is little argument, however, that the requirements of acoustic, classical singing differ from speech in at least three important ways: projection, intonation, and duration. In order to meet the musical and expressive demands of acoustic, classical vocal music, it would stand to reason that the manner in which a singer shapes the cavities and utilizes the articulators would differ from speech. Using the primary vowels /i e a o u/ as a point of reference, this document will begin by describing standard vocal tract configuration during speech. It will then take a chronological approach to detailing vocal tract shaping and use of articulators as they are outlined in both seminal and current vocal pedagogy texts. Finally, this document will attempt to categorize these findings to point out similarities and differences in thought. Keywords: Vowels, Formants, Articulation, Resonator, Vocal Tract TMUS 8329: Forming Formants 3 Forming Formants: Models of Vocal Tract Configuration for Sung Primary Vowels There are many well-known adages in the lexicon of vocal pedagogy, but perhaps none so infamous as “si canta come si parla.” Some cling to the idea that one sings as one speaks as though it were an absolute truth. While it may be more commonly used today in the instruction of contemporary music styles, perhaps this is only due to the decades of criticism this expression has received among experts in classical singing. Richard Miller’s March 1987 article in the NATS Journal drew attention to some of the issues related to this saying, an argument that continues to resonate with authors, as exemplified in the November 2018 Journal of Singing article, “Phonetic (L)imitation.” I have personally been familiar with the axiom for over 30 years and have heard it used in varying contexts. Nevertheless, I have never thought of it as a rule or being particularly instructive, but more as an aphorism. To me, it is a general observation regarding delivery; because the art of singing harnesses both music and text for communication, it is important that sung sounds come across to the listener in a manner similar to speech. That is to say, there are some qualities of speech that should be maintained in singing, particularly the elements of flow and prosody, including intonation, tone, stress, and rhythm. Authors critical of the saying and its application for classical singing have noted that singing and speech vary in at least three important ways: projection, intonation, and duration. In conversational speech, the proximity and size of the audience is minimal. Intensity levels, therefore, can remain relatively low while still being intelligible. In classical singing, the distance and size of the audience is far greater. In conversational speech, variation of pitch is rather limited – except in moments of heightened emotion. Intonation is typically limited to less than a perfect 4th up or down from the habitual or mean pitch, resulting in a functional pitch range of TMUS 8329: Forming Formants 4 less than an octave. Professional classical singers are required to have a functional pitch range of over two octaves in order to meet the demands of many compositions. With the exception of auctioneers and patter songs, duration varies greatly between speech and singing. It is frequently the case that the sung line is delivered at a slower tempo than in conversational speech, requiring greater specificity from the singer in defining vowel sounds and timing the change from sound to sound. Given the different requirements of speech and singing, along with the goal of having them interpreted similarly by the listener, there would seem to be a logical extension: in order for them to sound similar, they must be done differently. Nevertheless, after over 30 years of vocal instruction, it wasn’t until quite recently that the concept of singing articulation as being disparate from speech was approached in any formal or systematic way in my training. Of course, there were casual mentions regarding the formation of different sounds, such as “the edges of the tongue should stay in contact with the top teeth” or “the tip of the tongue should remain touching the bottom teeth.” After realizing some benefits from training a method of articulation that is singing-specific, my curiosity was sparked as to how leading pedagogues have approached the subject of articulation. Using the primary vowels /i e a o u/ as a point of reference, this document will begin by describing standard vocal tract configuration during speech. It will then take a chronological approach to detailing vocal tract shaping and use of articulators as they are outlined in both seminal and current vocal pedagogy texts. Finally, this document will attempt to categorize these findings to point out similarities and differences in thought. TMUS 8329: Forming Formants 5 Articulatory Phonetic Model: Speech Articulatory phonetics is the subfield of phonetics primarily concerned with how humans produce the sounds of speech, rather than the physical properties of spoken sounds, or acoustic phonetics. Singing voice science owes much of its foundational knowledge to these two disciplines; since the invention of the Bell Telephone in 1876 and the Edison Phonograph in 1877, linguists and acousticians have been using increasingly more sophisticated tools for recording, analyzing, and synthesizing the sounds of speech. Many of the acoustic and articulatory models for speech have been transferred and applied to singing, continuing to inform our current understanding. Fig. 1: Places of Articulation In figure 1, we see the places of articulation; these are the points in the vocal tract where maximum obstruction may occur due to the moveable structures. An obstruction is formed when two articulators move into proximity. The moving articulator is considered active, while the stationary one is considered passive. These places of articulation, where passive and active articulators meet, are labeled: 1. Exolabial, 2. Endo-labial, 3. Dental 4. Alveolar 5. Post-alveolar, TMUS 8329: Forming Formants 6 6. Pre-palatal, 7. Palatal, 8. Velar, 9. Uvular, 10. Pharyngeal, 11. Glottal, 12. Epiglottal, 13. Radical, 14. Postero-dorsal, 15. Antero-dorsal, 16. Laminal, 17. Apical, 18. Sub-apical. In the case of vowels, the structures that contribute the most are the cavities of the throat and mouth, or the laryngopharynx, oropharynx, and the oral cavity, the soft palate, the tongue, and the lips. The laryngo- and oro- pharynges, together with the oral cavity, are responsible for resonating the source harmonics that create the spectral tone colors that we identify as vowels. The bulge in the tongue divides or couples the pharynges and the oral cavity, raising or lowering the resonance frequency of the two spaces or encouraging them to resonate more as a singular cavity. The velum, or soft palate, can raise or lower, contributing the first formant space and controlling nasality. The lips can potentially shorten or lengthen the vocal tract by retracting at the corners (spreading or smiling) or protruding forward (puckering), raising or lowering all or the resonating frequencies of the vocal tract. Fig. 2: Describing Vowels Spoken vowels are described by a combination of factors, with the position of the highest point in the tongue being the primary descriptor. If the bulge in the tongue is close to the roof of the mouth, the vowel is considered “closed.” If the tongue is seated lower in the mouth, with the bulge of the tongue less pronounced, the vowel is considered “open.” When the highest point of the tongue is nearer to the anterior portion of the mouth, it is considered a “front” vowel, but when the highest point is approaching the posterior portion of the mouth, it is considered a TMUS 8329: Forming Formants 7 “back” vowel. There is also the distinction of the “central” vowel, where the bulge in the tongue is more toward the middle of the mouth. Fig. 3: Rounded vs. Unrounded Another dimension used to describe spoken vowels is rounded vs. unrounded. This value refers to the movement or shaping of the lips during articulation. This may not be the most accurate descriptor; for the rounded vowels there are varying degrees of “pucker” or moving the corners of the mouth inward and/or slightly forward, but for the unrounded vowels there is sometimes an element of “spreading” or pulling the corners of the mouth back. Loose and moon are fine examples of the rounding, while please and me often go beyond neutral to have an element of spreading. Chiba and Kajiyama’s research, detailed in The Vowel: Its Nature and Structure, is among the most comprehensive and influential works in the field of phonetics. Focusing on the primary vowels /i e a o ɯ/ (the unrounded /ɯ/ is more idiomatic to Japanese than the rounded /u/), their work is presented here as it is representative of the perspective of articulatory phonetics from the field of speech. In addition, it will provide a baseline for comparison with the varying positions on articulatory phonetics in singing. TMUS 8329: Forming Formants 8 /i/ Vowel Articulation Fig. 4: /i/ vowel articulation Articulation for the /i/ vowel is done with the bulge in the tongue toward the roof in the anterior portion of the mouth, or post-alveolar region, thus making it a “close unrounded front” vowel.