Original Research and
Acoustical Analysis in connection
with the Xöömij
Style of Biphonic Singing
Tran Quang
Hai , Centre National de la Recherche Scientitique,
Denis
GUILLOU, Conservatoire. National des Arts et Métiers,
Paris
The present article is limited in its
scope to our own original research and to acoustical analysis of biphonic
singing, this is preceded by a summary of the various terms proposed by
different researchers. The first half
the article concerning xöömij technique was written by Tran Quang Hai. Guillou has written the
second half concerning acoustical analysis.
Until the present time it has not been
possible to confirm that the centre, of biphonic singing within Turco‑Mongol
culture is in fact
Research can be carried out in various
ways: by means of observation of native performers after one or more visits to
the country concerned, or by means of practical instrumental or vocal studies aimed at a better understanding
of the musical structure employed by the population being studied. My own
research does not belong to either of these two categories since I have never
been to
Definition
Simultaneous two‑part singing by a single person is
known in the Mongol language as xöömij (literally "pharynx"). The
manner in which the Mongol word is transcribed is by no means uniform; homi, ho‑mi, (Vargyas 1968), khomi, khöömii, (Bosson 1964: 11), xomej, chöömej, (Aksenov 1964) chöömij, (Vietze 1969:15‑16. Walcott 1974) xöömij,
(Hamayon 1973). French researchers have used other terms to describe
this particular vocal technique such as chant
biphonique or diphonique (Leipp 1971,
Tran Quang Hai 1974). voix guimbarde. voix
dédoublee (Heitfer 1973, Hamayon 1973), and chant diphonique solo (Marcel‑Dubois 1979). Several terms exist
in English such as split‑tone singing, throat singing and overtone
singing, and in German sweistimmigen
Sologesang.
For convenience 1 have employed in
this article the term biphonic singing to describe a style of singing realized
by a single person producing simultaneously a continuous drone and another sound
at a higher pitch issuing from a series of partials or harmonies resembling the
sound of the flute.
Origin of My Research
In 1971, the date of my first contact with Mongolian music in
the form of recordings made in Mongolia between 1967 and 1970 by Mrs. Roberte
Hamayon, researcher at the Centre National de la Recherche Scientifique and
especially after listening to a tape on which were recorded three pieces in the
biphonic singing style, I was struck by the extraordinary and unique nature of
this vocal technique.
For several months I carried out
bibliographical research into articles concerned with this style of singing
with the aim of obtaining information on the practice of biphonic singing, but
received little satisfaction. Explanations of a merely theoretical and
sometimes ambiguous nature did nothing so much as to create and increase the
confusion with which my research was surrounded. In spite of my complete
ignorance of the training methods for biphonic singing practised by the
Mongols, the Tuvins and other peoples, I was not in the least discouraged by
the negative results at the beginning of my studies after even several months
of effort.
Working Conditions
According to Hamayon, the xöömij, which exists throughout
The xöömij refers to the simultaneous production of two
sounds, one similar to the fundamental produced on the Jew's harp (produced at
the back of the throat), and the other resulting from a modification of the
buccal cavity without moving the lips which remain only slightly open;
positioning the lips as for a rear vowel results in a low sound, whereas front
vowel positioning produces a high sound (Hamayon 1973), a technique similar to
that used by the Tuvins (Aksenov 1964). The cheeks are tightened to such a
degree that the singer breaks out into a sweat. It is the position of the
tongue which determines the melody. Anybody who possesses this technique is
able to copy any tune (Hamayon 1973).
1 worked entirely alone groping my way
through the dark for two yews, listening frequently to the recordings made by
Hamayon stored in the sound archives of the ethnomusicology department of the Musee de I'Homme. My efforts were however to no avail. Despite
my efforts and knowledge of Jew’s harp technique, the initial work was both
difficult and discouraging. 1 also tried to whistle while producing a low sound
as a drone. However, checking on a sonograph showed that this was not similar
to the xöömij technique. At the end of 1972 I got to the stage that I was able
to produce a very weak harmonic tone which when recorded
on tape, showed that 1 was still a long way from my goal.Then,
one day in November 1973, in order to calm my nerves in the appalling traffic
congestion of Paris, I happened to make my vocal chords vibrate in the pharynx
with my mouth half open while reciting
the alphabet. When I arrived at the letter L and the tip of my tongue was about
to touch the top of my mouth, I suddenly heard a pure harmonic tone, clear and
powerful. I repeated the operation several times and each time I obtained the
same result. I then tried to modify the position of the tongue in relation to
the foot of the mouth while maintaining the low fundamental. A series of
partials resonated in disorder inside my ears.
At the beginning I obtained the harmonics of a perfect chord.
Slowly but surely, after a week of intensive work, by changing the fundamental
tone upwards or downwards, 1 had managed to discover all by myself a vocal
jaw's harp technique or biphonic singing style which appeared to be similar to
that used by the Mongols and the
Tuvins.
Basic Techniques
After two months of research and numerous experiments of all
kinds I was able to establish some of the basic rules for the realization of
what I call biphonic singing.
1) Half open the mouth.
2) Emit
a natural sound on the letter A without forcing the voice and remaining in the
middle part of the vocal range (between F and A below middle C for men, and
between F and A above middle C for women).
3) Intensify the vocal production while vibrating the vocal
chords.
4) Force out the breath and hold it for as long as possible.
5) Produce the letter L. Maintain the position
with the tip of the tongue touching the roof of the mouth.
6) Intensify the tonal volume while
trying to keep the tongue stuck firmly against the palate in order to divide
the mouth into two cavities, one at the back and one at the front, so that the
air column increases in volume through the mouth and the nose.
7) Slowly pronounce the sounds represented by the phonetic signs "i" anti “u” while varying the position of the lips.
8) Modify the buccal cavity by changing the
position of the tongue inside the mouth without interrupting or
changing the height of the fundamental already amplified by the
vibration of the vocal chords.
9) In this way it is possible to obtain both the
drone arid the partials or harmonics either in ascending or descending order
according to the desire of the singer.
For beginners the harmonics of the
perfect chord (C. E. G. C) are easy to obtain. However, a considerable amount
of hard work is necessary especially to obtain a pentatonic anhemitonic scale.
Every person has his favourite note which permits him to produce a large range
of partials. This favourite fundamental tone varies according to the tonal
quality of the singer's voice and his windpipe. It often happens that two people
using the same fundamental tone do riot necessarily obtain the same series of
partials.
Regular practice and the application
of the basic techniques which 1 have just described above permitted me to
acquire a range of between an eleventh and a thirteenth according to the choice
of the drone. Biphonic singing can also be practised by women and children, and
several successful experiments have been carried out in this connection.
Other experiments which I have been
carrying out recently indicate that it is possible to obtain two simultaneous
sounds in two other ways. In the first method, the tongue may be either flat or
slightly curved without actually at any stage touching the root of the mouth,
and only the mouth and the lips move. Through such variation of the buccal
cavity, this time divided into a single cavity it is possible to hear the
partials faintly.
In the second method the basic technique described above is used. However
instead of keeping the mouth half open it is kept almost completely shut with
the lips pulled back and very tight. To make the partials audible, the position
of the lips is varied at the same time as that of the tongue. The partials are
very clear and distinctive, but the technique is rather exhausting and it is
not possible to sing for a long time using it.
In the northeast of
Biphonic singing is also practised by
a number of ethnic groups in the republics of the Soviet Union bordering on
The late John Levy made a recording in
Rajasthan in 1967 on which can be heard an example of biphonic singing similar
to that practised by the Mongols and the Tuvins (1). The virtuoso performer in
the recording imitates the double flute called the satara (an instrument
producing simultaneously a drone and a melody) or the Jew's harp with his
voice. However, this may well be an exceptional example in that no mention is
ever made of biphonic singing techniques in the musical traditions of Rajasthan
or elsewhere in
Tibetan monks, particularly those in
the monasteries of Gyume and Gyuto(2), make use of a
technique using two simultaneous voices, although this technique is far less
developed than that used by the Mongols and the Tuvins. The low register of the
drone makes it impossible to produce harmonics as clear and resonant as those
emitted by the Mongols and the Tuvins, and furthermore the production of
harmonics is not the aim of Tibetan Buddhist chant.
In Western contemporary music groups of singers have also
succeeded in emitting two voices at the same time and vocal pieces have been
created in the context of avant‑garde music (3) and in recent years of
electronic music (4).
An X-ray film was mode for the first
time in 1974 at the Centre Medico‑chirurgical of the Porte do Choisy in
Paris at the request of Professor S. Borel‑Maisonny, speech therapist and
of Professor Emile Leipp, acoustician. This film which was made with the
cooperation of the present author made it possible to examine closely the
internal functioning and placement of the tongue during biphonic singing, and
was thus of great interest. Thanks to this film the author has improved his
biphonic singing technique as a result of which he has been able to decrease
the volume of the drone and increase that of the harmonics.
Table 1 Characteristics of the biphonic singing styles of the Tuvins
sygyt ezengileer kargyraa borbannadyr
Pitch of Changes in the No
change No change, No change
the drone or course of singing although sometimes
fundamental lowered
by a minor
third
Tonality More intense and Same as sygyt low Soft
higher than that of
the kargyraa style
Position Half open Half open Half
open Almost closed
of tile
mouth
Harmonics 8, 9, 10 for uneven (6), 8, 9, 10, (6), 8,.9,
10,11.2 6, 7, 8, 9,10, 12.
or partials verses 11,
12,13 13
8,
9, 10, 12 for
even verses
Special ‑Harmonics used ‑Alternation
of ‑Each vowel ‑Occasionally
features as
an ostinato strong and weak corresponds to a three voices with
accompaniment. accents like a partial two used as a
thus resulting in a gallop rhythm ‑Psalmodic drone: tonic and
narrow range recitation
with or fifth (in exceptional
‑in
the course of without
special cases) and third
a. song, at the end text
on 2 pitches voice producing
of each phrase a or
drone in 2 harmonics
note is held 1
positions rising and ‑Called khomei
in
(fundamental for descending
by a certain areas,
uneven verses, or a minor
third
descending tone ‑Called
borban
for even verses) nadrt
in cases
when the borban
nadyr is named
khomei
Acoustical Analysis‑introduction
The present study is concerned with biphonic singing its
understanding and interpretation, and does not constitute a complete and
definitive piece of research. In fact the discovery of certain phenomena
permits us only to imagine what might be the reality, this being particularly
true in relation to the mechanism involved in the production of biphonic
singing. Thus it will be necessary to carry out further research in the
following areas: psycho ‑acoustics and particularly the perception of
pitch and phonatory acoustics.
Biphonic singing differs from so‑called natural singing
on account of its sonority as well as of course the vocal technique involved.
As its name indicates it consists of two sounds. On the basis of simple aural
observation, it is possible to distinguish a first sound whose pitch is
constant and which we shall call the drone and a second sound which takes the
form of a melody which the singer can produce at will. It is basically possible
for anybody to produce this biphonic sonority but to make the second voice dominate
and to trace a melody with it depends upon the talent of the artist.
Firstly, we shall examine the concept of pitch perception in
terms of acoustics and psycho‑acoustics. Secondly we shall try to define
biphonic singing, to differentiate it from other vocal techniques and to
specify its scope. It will then be worthwhile to formulate several hypotheses
concerning the mechanism whereby this style of singing is produced and finally
to present a few examples of such a technique.
Pitch Perception
It is first of all necessary to comprehend exactly what is
meant by the pitch of sounds or tonality. This concept presents a considerable
amount of ambiguity and does not correspond to the simple principle of the measurement
of the frequencies produced. The pitch of sounds is related more to psycho-acoustics
than to physics.
Our own proposals are based partially on the recent
discoveries of certain researchers, and partially on observations which we have
made ourselves with the help of a sonagraph machine.
The sonagraph makes it possible for us to obtain the image of
the sound which we wish to study. On a single piece of paper is given
information concerning time and frequency, and, in accordance with the
thickness of the line traced information concerning intensity.
The classical manuals on acoustics tell us that the pitch of
harmonic sounds, that is sounds with, for example a fundamental with the frequency
F and a series of harmonic, F1, F2. F3.... multiples of F. is determined by the
frequency of the first fundamental F. This is not entirely correct in that it
is possible to suppress electronically this fundamental without thereby
changing the subjective pitch of the actually perceived sound. If this theory
were correct an electro‑acoustic chain not reproducing the lowest sound
would change the pitch of the sounds. This is evidently not the case since the
tonal quality changes but not the pitch. Certain researchers have proposed a
theory which would appear to be more coherent: the pitch of sounds is
determined by the separation of the harmonic lines or the difference in
frequency between two harmonic lines. What is the pitch of the sounds, in this
case for sonic spectra with “partials" (harmonics are not complete
multiples of the fundamental)? In this case, the individual perceives an
average of the separation of the lines in the zone which interests him. This in
fact corresponds with the differences in perception which may be observed from one individual to the other (Fig. 1).
Fig. 1 Sonagram
representation of three types of sound
a) Harmonic
spectrum: the harmonics are whole multiples of the fundamental.
b) Partials
spectrum: the harmonics are no longer whole multiples of the fundamental.
c) Formant
spectrum: two harmonics are intense and constitute a formant in the harmonic spectrum.
Formant spectrum: the accentuation in intensity of a group of
harmonics constitutes a formant and is thus a zone of frequencies in which
there is a large amount of energy.
Taking this formant into consideration a second concept of the
perception of pitch comes to light. It has in effect been established that the
position of the formant in the sonic spectrum results in the perception of a
new pitch. In this case it is no longer a matter of the separation of the
harmonic lines in the formant zone but of the position of the formant in the
spectrum. This theory should be qualified however, since conditions also have
to be considered.
Experiment: Tran Quang Hai sang two
C's an octave apart making his voice carry as if he
were addressing a large audience. We observed, using a sonagram, that the
maximum energy was situated in the zone perceptible by the human car (3, 4 KHz)
and that the formant was situated between 2 and 4 KHz. We then recorded two C's
an octave apart in the same tonality, but this time he used his voice as it
addressing a small audience, and we observed the disappearance of this formant
(Fig. 2‑a. 2‑b).
In this case the disappearance of the formant does not change
the pitch of the sounds. We then rapidly observed that the perception of pitch
through the position of the formant was only possible it the formant was very
acute for knowing that the sonic energy was only divided on two or three
harmonics. Thus if the energy density of the formant is large and the formant
is narrow the formant gives information concerning the pitch as well as the
overall tonality of the sonic item. Through this expedient we arrive at the biphonic vocal technique.
Fig. 4
a) Sonagraph representation of normal singing.
An octave passage is equivalent to a doubling of the gap between the harmonic
lines and to a drone of double frequency, (The first bar represents the base
line of the sonagram, and the drone is represented by the second bar.)
b) Sonagraph
representation of biphonic singing. An octave passage is represented by a
displacement of the formant. The harmonic lines of the formant are displaced
in a zone in which the frequency is doubled.
Comparison between
Biphonic Technique and Classical Technique
It may be said that biphonic singing consists as its name indicates,
of the production of two sounds, one a drone which is low and constant, and the
other at a higher pitch consisting of a formant which displaces itself in the
spectrum in order to produce a certain melody. The concept of pitch given by the
second voice is moreover somewhat ambiguous. The Western ear may need a certain
amount of training before becoming accustomed to the sound quality.
Evidence concerning the drone is relatively easy to obtain
thanks to the sonagram: it can be seen clearly and is also very clear on an
auditory level. The device in Fig. 3 also makes it possible to see a pure
amplitude frequency of a constant nature.
Fig. 3. Device for
providing evidence of perfect constancy of the drone in intensity and frequency.
After having examined the fundamental
tone we compared two spectra, one of biphonic singing and the other of the so‑called
classical singing style, the two being produced by the same singer. The sonagrams
of these two types of singing are shown in Fig. 4. Classical singing is
characterized by a doubling of the separation of the harmonic lines when an
octave is exceeded (a). Biphonic singing is characterized on the other hand by
the fact that the separation of the lines remains constant (this was foreseeable
since the drone is constant), and that the formant is displaced by an octave
(b). In fact it is easy to measure the distance between the lines for each
sound. In this case, the perception of the melody in biphonic singing works
through the expedient of the displacement of the formant in the sonic spectrum.
It should be stressed that this is only really possible if the
formant is high, and this is obviously so in the case of biphonic singing. The sonic energy is divided principally between
the drone and the second voice consisting of two or at the most three
harmonics.
It has sometimes been stated that it is possible to produce a
third voice. Using the sonagrarn we have in actual fact established that this
third voice exists (see sonograms of Tuvin techniques), but it is impossible to
state that it can be controlled. In our opinion this additional voice results
more from the personality of the performer than from any particular technique.
As a result of our work we have been able to establish a
parallel between biphonic singing and the technique of the Jew’s harp. As in
the case of biphonic singing the Jew's harp produces several different voices,
the drone, the main melody and a counter melody. We may consider this third
voice as a counter melody which may be produced on a conscious level but can
presumably not be controlled.
As far as possibility of variation is concerned, biphonic
singing is the same as normal singing except in connection with pitch range.
The time of execution is evidently a function of the thoracic
cage of the singer and thus of breathing, since the intensity is related to the
output of air. Possibility of variation with regard to intensity is on the
other hand relatively restricted and the level of the harmonics is connected to
the level of the drone. The singer has to try and retain a suitable drone and
produce the harmonics as strongly as possible. We have already observed that
the clearer the harmonics the more the formant is narrow and intense. We are
able furthermore to observe connections between intensity, time and clarity.
Possibility of variation in relation to tone quality may pass without comment,
since the resulting sound is in the majority of cases formed from a drone and
one or two harmonics. The most interesting question is that of pitch range.
It is generally accepted that, for a sensible tonality (in
consideration of the performer and of the piece to be performed a singer may
modulate or choose between harmonics 5 and 13. This is true but should be
stated more precisely. The range is a function of the tonality. If the tonality
is on C2, the range represents nine harmonics from the fifth to the thirteenth,
this involving a range of a major thirteenth. If the tonality is raised for
example to C3 the choice is made between six harmonics, numbers 3 to 8 (see
Table 2), representing an interval of an seventh. The following remarks should
be made in this context. Firstly, the pitch range of biphonic singing is more
restricted than that of normal singing. Secondly, the singer theoretically
selects the tonality which he wishes between
C2 and C3. In practice however, he instinctively produces a compromise between
the clarity of the second voice and the pitch range of his singing, since the choice of the tonality is also a function of
the musical piece to be performed. Thus if the tonality is raised, for example
to C3, the choice of harmonics is restricted but the second voice is very
clear. In the case of a tonality on C2 the second voice is more indistinct
while the pitch range is at a maximum. The clarity of the sounds can be
explained by the fact that in the first case, the singer is only able to select
a single harmonic, whereas in the second case, he may select almost two (see
Fig.5). As far as pitch range is concerned, it is known that the movement of
the buccal resonators is independent of the tonality of the sounds produced by the
vocal chords, or, put in another way. The singer always selects harmonics in
the same zone of the spectrum whether the harmonics are broad or narrow.
It results from all this that the singer chooses the tonality
instinctively in order to have the maximum range and clarity. For Tran Quang
Hai, the best compromise exists between C2 and A2. He can thus obtain a range
of between an octave and a thirteenth.
Mechanism for the
Production of Biphonic Singing
It is always very difficult to know what is taking place
inside a machine when we are placed outside it and can only watch it in
operation. This is the case with the phonatory mechanism. The following remarks
are only approximate and of a schematic nature and should not be assumed to be
the final word on the subject. In dealing by analogy with the phonatory system
we can get an idea of the mechanisms but surely not a complete explanation.
Fig. 6 is a representation of the phonatory system which can be compared with
Fig. 7, showing an excitation system producing harmonic sounds and a series of
resonating systems amplifying certain parts of this spectrum.
A resonator is a cavity equipped with a neck capable of resonating
in a certain range of frequencies. The excitation system, i.e., the pharynx and
the vocal chords emits a harmonic spectrum consisting of the frequencies F1,
F2. F3. F4 ... of resonators which select certain frequencies
and amplify them. The choice of these frequencies evidently depends upon
the ability of the singer. This is the case when a singer projects his voice
within a large hail in that he instinctively adapts his resonators in order to
produce the maximum energy within the area in which the ear is sensitive.
It should be noted that the amplified frequencies are a
function of the volume of the cavity, the section of the opening and the length
of the neck constituting the opening:
Through this principle it is possible to see already the
action of the size of the buccal cavity, of the opening of the mouth, and of
the position of the lips during singing.
However, this does not tell us anything about biphonic
singing. In practice we need two voices. The first, the drone, is given to us
simply by virtue of the fact that its production is intense, and that in any
case, it does not undergo filtering by the resonators. Its intensity, higher
than that of the harmonics, permits it to survive on account of buccal and
nasal diffusion. We have observed that as the nasal cavity was closed, so the
drone diminished in intensity. This occurs for two reasons, firstly that a
source of diffusion is closed through the nose and secondly, by closing the
nose the flow of air is reduced, as is the sonic intensity produced at the
level of the vocal chords.
The possession of several cavities is of prime importance. In
practice, we have established that only coupling between several cavities has
enabled us to have a sharp formant such as is required by biphonic singing.
For the purposes of this research we initially carried out
investigations into the principle of resonators in order to determine the
influence of the fundamental parameters. It was observed that the tonality of
the sound rises if the mouth is opened wider. In order to investigate the
formation of a sharp formant, we carried out the following experiment. Tran
Quang Hai produced two kinds of biphonic singing, one with the tongue at rest.
i.e., not dividing the mouth into two cavities and the other with the mouth
divided into two cavities. The observation which we made is as follows (an
observation which could have been foreseen on the basis of 
the theory of coupled resonators). In the first case the
sounds were not clear: the drone could be heard distinctly but the second voice
was difficult to bear. There was no clear distinction between the two voices,
and, furthermore, the melody was indistinct. The corresponding sonagrams bore
this out: with a single buccal cavity the energy of the formant is dispersed
over three or four harmonics and so the sense of a second voice is very much on
the weak side. On the other hand, when the tongue divides the mouth into two
cavities, the formant reappears in a sharp and intense manner. In other words,
the harmonic sounds produced by the vocal chords are filtered and amplified in
a rough manner with a single buccal cavity and the biphonic effect disappears.
Biphonic singing thus necessitates a network of very selective resonators which
filters only the harmonics required by the singer. Fig. 8 shows the responses in
frequencies of the resonators, both simple and coupled. In the case of a tight
coupling between the two cavities, these produce a single and very sharp resonance.
If the coupling is loose, the formant has less intensity and the sonic energy
in the spectrum is stemmed. If the cavities are transformed into a single
cavity, the pointed curve
becomes even rounder, and one ends up with
the first example with a very blurred type of biphonic singing (tongue at
rest). The conclusion can be drawn that the mouth along with the position of
the tongue plays the major role, and it can be compared roughly to a pointed filter
which changes its place in the
spectrum with the sole aim of selecting the interesting harmonics.
We should like to express our gratitude and sincere thanks to
Research Team 165 of the Centre National de la Recherche Scientifique directed
by Mr. Gilbert Rouget, who allowed us access to valuable documents concerning
biphonic singing stored in the sound archives of his department. Our thanks go
also to Professor Claudie Marcel‑Dubois, Head of the Department of
Ethnomusicology at tile Musee National des Arts et Traditions Populaires, who
gave us a great deal of help and encouragement. We should like also to thank Professor
Emile Leipp, Dr. Michele Castellango and Professor Solange Borel‑Maisonny,
who made it possible for us to examine the internal functioning of biphonic
singing by means of the production of a radiographic film.
(Translated from French by Robin THOMPSON)
NOTES
1. This tape is preserved in the
Ethnomusicology Department of the Musee de L’Homnic.
number BM 78 2, 1.
2. See the record “The Music of
Tibet." recorded by Peter Crossley‑Holland, Anthology Records
(30133)
AST 4005,
3. See the record “The tail of the
Tiger.” Ananda 2.
4. An example is the electronic music composition entitled “Ve
nguon” (Return to the Source), composed
by
Nquyen Van Tuong, with Tran Quang Hai as soloist. The first performance was
given in
1975. The third movement (25 minutes) uses biphonic
singing.