Polyphonic Overtone Singing: an Acoustic and Physio- Logical (MRI) Analysis and a First-Person Description of a Unique Mode of Singing
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Proceedings from FONETIK 2019 Stockholm, June 10–12, 2019 Polyphonic Overtone Singing: an acoustic and physio- logical (MRI) analysis and a first-person description of a unique mode of singing 1 2 3 Anna-Maria Hefele , Robert Eklund , Anita McAllister 1 http://www.anna-maria-hefele.com 2 Department of Culture and Communication, Linköping University, Sweden 3 Division of Speech and Language Pathology, Karolinska Institutet, Sweden [email protected], [email protected], [email protected] Abstract However, Miles did not leave any This paper describes a unique singing marked traces in musical history, alt- mode, tentatively labeled “polyphonic hough he was a local celebrity and even overtone singing”. In overtone singing released an album (Tongeren, the vocal harmonics of a stabile funda- 2004:161). Also in America, La Monte mental frequency are filtered by the Young began to experiment with vocal singer in such a way that specific upper overtones and started to use it as a musi- harmonics are amplified, and heard cal parameter, although it was not yet clearly, as a second musical voice. In the mature overtone singing (Tongeren, “throat singing” of Tuva (Mongolia) 2004:166). moving overtones usually occur over a In 1968 Karlheinz Stockhausen pub- stable drone. In polyphonic overtone lished Stimmung for six vocalists, which singing not only the pitch of the over- can be considered the first composition tones are changed and moving, but also in contemporary music with exact, no- the fundamental which results in two- tated vocal overtones, amplified through voice singing. specific vowels (Saus, 2009:1). Further, Michael Vetter (Germany), Introduction who collaborated with Stockhausen The historical records of overtone sing- from 1969 (Tongeren, 2004:177), and ing (OTS) are fairly scarce. It is used in David Hykes “laid the solid foundations different ethnic traditions and musical for overtone singing as an independent styles. A well-known example is the vocal technique /…/ With their original “Tuvan throat-singing” (Levin & Edger- examples, overtone singing became an ton, 1999), which mainly occurs in Mon- art in itself” (Tongeren, 2004:175). golia and Tibetan temples (Smith, Ste- The Greek singer Demetrio Stratos vens & Tomlinson, 1967). Singers in (1945–1979) also belongs to the first these regions employ a variety of throat- generation of experimental western singing styles, referred to as sygyt, overtone singers, and before his early chöömej and kargyraa (Grawunder, death he left his album Cantare la Voce 1999:22). Chöömej is also used as an (1978) with “vocal sounding overtone umbrella term for all central Asian tech- noises” (Tongeren, 2004:175). niques. Trân Quang Hai (1944–), a Viet- In the west, the tradition of OT is not namese musician and researcher living as strong, and the development of the in Paris, got in contact with Mongol technique began during the last century. overtone singing in 1969 and he “collab- The earliest existing recording of west- orated in one of the first compositions ern OTS is from 1929, sung by an Amer- and public performances of OTS in Eu- ican country singer, Arthur Miles. rope after Stockhausen /.../ Apart from 91 Proceedings from FONETIK 2019 Stockholm, June 10–12, 2019 his activities as a performer, Trân’s main The techniques contribution to the field of overtone In the western style of overtone singing singing are scientific and educational” a distinction can be made between the (Tongeren, 2004:171). so-called one-cavity-technique, where From 1983 and on OTS became harmonics get amplified through spe- popular also outside the field of experi- cific vowel shapes and the so-called two- mental music and the knowledge about cavity-technique, where the tongue is the technique grew. Singing groups and raised and divides the oral cavity into overtone choirs were formed for chant- two resonance chambers. This results in ing, singing mantras or practicing over- very clear, whistle-like harmonics. The tone singing together, so it was not only differentiation between these two tech- performed by professional musicians niques was first performed by the ethno- (Tongeren, 2004:185). So called “World musicologists Tran Quang Hai and Hugo Music” gained popularity in the west, Zemp, based on physiological research which spurred an interested in overtone (Jentsch 2007:55). singing. Also enhanced by the Tuva En- The one-cavity technique enhances semble tours (Tongeren, 2004:187). To- the harmonics through changing the day western overtone singing is used in vowel shapes, mostly over a stabile fun- many different musical genres. damental. This is usually the first tech- From a phonetic perspective, the nical stage to learn in OTS. formant tuning and the adjustments of the articulators during OTS, are of inter- Results est both with regard to aspects related to Below different possibilities with OTS production and pedagogy. are explored. As seen in the spectrogram Method and material in Figure 1, overtones can be clearly vis- ualized over a stabile fundamental. Note The study includes acoustic analysis of that a drone would have the same func- OTS performed by the first author tion. Below the spectrogram the simulta- (AMH in the following). In all spectro- neous MRI registrations are shown. Also grams the program Overtone Analyzer note the different and peculiar tongue (https://www.sygyt.com/en) was used. shapes used to enhance the partials. This The MRI recordings were made at Frei- is especially apparent in the initial burg University Hospital, using a 3T frames. The technique used for this anal- Siemens Prisma Fit scanner. MRI re- ysis is the two-cavity technique. cordings were completed in collabora- Another possibility within the two- tion with professor Bernhard Richter, Dr cavity technique is to move overtone and Michael Burdumy and the singer at an fundamental in parallel, or to leave the earlier date. The MRI-llustrations are harmonics stabile and move the funda- provided by the singer AMH. mental through the subharmonic series The singer as shown in Figure 2. By alternating the fundamental fre- AMH is a classically trained soprano quency different overtones can be en- with a wide frequency range of around hanced as shown in Figure 3. Here two ~100–2000 Hz. She started with over- alternating fundamentals and their har- tone singing in 2005 and now cooperates monics are combined using the two-cav- with several musicians and composers to ity technique. increase knowledge about the musical possibilities of the technique. AMH is also teaching overtone singing in mas- terclasses around the world. 92 Proceedings from FONETIK 2019 Stockholm, June 10–12, 2019 Figure 1. Harmonics 4-10 amplified in the two-cavity technique from fundamental C4. Figure 5 the spectrogram of the first phrase of “Sehnsucht nach dem Früh- linge” by W.A. Mozart is shown. The fundamental is not moved randomly but rather chosen within the overtone- and subharmonic series and within the singer’s voice range. Within these op- tions harmonics are chosen that deliver a harmony or create a counterpoint move- ment. This provides a harmonic context Figure 2. A stable harmonic and a moving fundamental. to the melody in OT. Figure 4. Fundamental and overtones mov- ing in opposite directions, resulting in a mu- sical counterpoint. Figure 3. Overtones over two alternating fundamentals. To result in polyphonic overtone sing- ing, different combinations of move- In Figure 4 AMH illustrates how ments for overtones and fundamentals overtones and fundamentals can be are used. In the figure three combina- moved in opposite directions. This re- tions of movements for the overtones sults in creating a musical counterpoint. and the fundamentals are displayed. Thus, simple classical songs or folk mel- odies can be easily arranged for OTS. In 93 Proceedings from FONETIK 2019 Stockholm, June 10–12, 2019 Figure 6. To the left overtones and f0 is shown while moving from /i/ to /u/ in one- cavity technique. To the right the same movement from /i/ to /u/ while whispering, Figure 5. Three combinations of movements illustrating filtering of the vocal tract. for overtones and fundamentals are shown. Discussion In this example it is the first phrase of “Sehnsucht nach dem Frühlinge” by W.A. In the present study OTS produced by Mozart. one singer using two techniques was an- alysed. Previously the enhancement of The physiology of overtone singing harmonics has been attributed to a nar- In the one-cavity-technique the vowel rowing of pharynx and the velar con- transition between /i/ and /u/ is used, as striction, adjusting the mouth opening in the slowly spoken words “oui” and and a tuning of F1 and F2 (Klingholz “you”. Here only the movement of the 1993). In this study we showed that the second formant is enhancing harmonics, formant tuning mainly involves F2 and see Figure 6. In the second panel of the F3 and that several other alterations are figure the same movement was executed involved, such as tongue elevation and but while whispering, to illustrate the ef- shape, lips and jaw position. Also the al- fects of the vocal tract. terations differ depending on whether a In the two-cavity technique the ele- one- or a two-cavity technique was used. vation and shape of the tongue creates Thus, OTS requires precision and timing two separate resonatory chambers. The of the motor control of the articulators tongue shape is similar to a /l/ or /ɹ /. The and a very accurate pitch perception. third formant is lowered and brought close to the second by a raised tongue. OT singing: A first-person account The 2nd and 3rd formant are coordinated When learning OTS, one learns to per- and moved through the spectrum almost ceive harmonics as musical notes or at the same frequency (Saus, 2016:450), pitches, while they are usually perceived amplifying the same harmonic.