Growl Voice in Ethnic and Pop Styles
Ken-Ichi Sakakibara, Leonardo Fuks, Hiroshi Imagawa,
Niro Tayama 2004
Abstract
Among the so-called extended
vocal techniques, vocal growl is a rather common effect in some ethnic (e.g.
the
Xhosa people in
This
paper examines growl mechanism using videofluoroscopy and high-speed imaging,
and its acoustical characteristics by spectral analysis and model simulation. In
growl, the larynx position is usually high and aryepiglottic folds vibrate. The
aryepiglottic constriction is associated to a unique shape of the vocal tract,
including the larynx tube, and characterizes growl.
1. Introduction
The term growl is originally
referred to as low-pitched sounds uttered by animals, such as dogs, or similar sounds
by humans, and therefore is mainly described by auditory-perceptual impression.
Growl is widely observed in singing as well as in shouting and aroused speech.
The
growl phonation has been also referred to as the phonation observed in some
singing styles, such as the jazz singing style of Louis Armstrong (1Satchmo’s
voice quality revealed roughness in the vocal fold level, however, he often
used growl) and Cab Calloway, [2, 3]. Many jazz, blues, and gospel singers
often use growl in a similar manner. Besides such pop music from North America,
growl styles are widely found in pop music of other areas: in
In
ethnic music, one of the most prominent uses of growl is found in umngqokolo,
which is a vocal tradition of the Xhosa people in
Growl may have perceptual
similarities with the rough or harsh voice. In terms of phonetics, growl is
sometimes described as the voiced aryepiglottic trill [3]. However, there is no
clear evidence of its production mechanism, such as physiological observation
of the aryepglottic vibration.
In throat singing (Tyvan khöömei
and Mongolian khöömij), ventricular and vocal fold vibration was observed for
the two different laryngeal voices (drone and kargyraa) [4, 9]. In drone, the
basic voice in throat singing with a whistle-like high overtone, the
ventricular fold vibration is at the same frequency as the vocal fold vibration.
I kargyraa, which usually sounds one octave (or more) lower than the modal
register, the ventricular folds vibrate at F0/2 when the vocal folds vibrate at F0. Moreover,
some singers can do triple-periodic kargyraa in which the ventricular folds
vibrate at F0/3. In this paper, the phonation mode with ventricular and vocal
fold vibration is called VVM (vocal-ventricular mode) [4]. In growl, there is
no clear evidence of the ventricular fold vibration.
The
growl, drone, kargyraa, as well as vocal fry, and some pathological voices may
have similar perceptual characteristics related to roughness, creakiness, or
harshness. Their acoustics may also have similar features. Therefore,
clarifying differences among these phonations requires careful physiological
observation.
In
this paper, we examine the production mechanism of the growl phonation. Some of
the authors (KIS, LF), who can utter several phonation modes, including the VVM,
produced the growl phonation by carefully listening to and imitating various
samples, as mentioned above. Observation of the laryngeal adjustment using
endoscopic high-speed imaging and X-ray videofluoroscpy (partly reported in
[1]), confirm the aryepiglottic vibration in growl. We also discuss the
acoustical characteristics and differences between VVM (in particular,
kargyraa) and growl.
2. Three-tiered sphincter of the larynx
In the human larynx, there is
a three-tiered sphincter comprising the vocal folds, the ventricular folds
(false vocal folds), and the aryepiglottic sphincter [7] (Fig. 1).
The
ventricular folds are incapable of becoming tense, since they contain very few
muscle fibres. However, the ventricular folds can be constricted by the action of
certain intrinsic laryngeal muscles. In the aryepiglottic region, the
constriction is caused by the approximation of the tubercle of the epiglottis
(anterior), aryepiglottic folds (lateral), and arytenoids (posterior). In
normal phonation, the vibration of the ventricular and aryepiglottic folds is not
observed.
3. X-ray observation
We observed the vertical
laryngeal configuration of three different types of phonations (modal,
“metallic”, and growl) using X-ray cinematography.
Fig.
2 shows a lateral X-ray view of the phonatory apparatus at rest. A wide
pharyngeal space between the epiglottis and the arytenoids is observed. The
cricoid cartilage is located at about the level of the fifth cervical
vertebrae.
Fig. 3 shows
the lateral X-ray views of three different voices: modal (left), “metallic” (centre),
and growl (right), in /y/ (close front rounded vowel). The metallic voice has a
perceptually metallic impression and, in terms of usual phonetic usage, can be
interpreted as pharyngealized, a little pressed (not necessarily tense), and raised-larynx.
White lines are traced along the edges of the cricoid, arytenoid, epiglottis,
and cervical column. In modal phonation, a wide pharyngeal space is observed.
The
epiglottis doesn’t depress and its position is almost similar to that when it
is at rest. In metallic and growl, the larynx is raised to about the level of
the fourth cervical vertebrae. The epiglottis and arytenoid approximate very
closely. There is no significant difference of the laryngeal adjustments
between metallic and growl.
4. High-speed images
We observed
laryngeal movements in growl directly and indirectly by simultaneous recording
of high-speed digital images, EGG (Electroglottography) waveforms, and sound
waveforms. The high-speed digital images were captured at 4500 frames/s through
an endoscope inserted into the mouth cavity of a singer. Sound and EGG
waveforms were sampled at 12 b/s and 18 kHz sf.
In
growl phonation, the aryepglottic region is compressed antero-posteriorly, and
the tubercle of the epiglottis and the arytenoid cartilages come into contact
(Fig. 4).This antero-posterior compression is in good agreement with the
lateral view of growl phonation in Fig. 3. Two sided chinks generated by the
contact of the epiglottic tubercle and arytenoids were observed. Each chink is surrounded
by the epiglottis, arytenoid, and an aryepiglottic fold. In some cases, both
aryepiglottic folds vibrate in almost same phase (Fig. 5), and in other cases,
the phases of both seem to be slightly different. Furthermore, in some cases,
the vibration of the aryepiglottic folds is unstable and seems to be aperiodic.
Fig. 5 shows the sound
waveform (top), EGG waveform (middle, ordinate corresponds to total contact
area of the larynx), and high-speed images. Vertical lines in the sound and EGG
are synchronous to the last frames in each column of the high-speed images. The
vibrations of the aryepglottic folds are observed in the high-speed images.
In this case, the
aryepiglottic fold vibration is likely to be periodic and the vibration of each
side is mostly synchronous.
From
the EGG and sound waveform, it is reasonable to conclude that the vocal folds
vibrate half-periodically to the aryepiglottic fold vibration. This vibration
pattern of the vocal and aryepiglottic folds is same as the VVM with F0/2, i.e.
kargyraa. The period-double vibration of the aryepiglottic folds generates
subharmonics.
Neither
the vocal nor ventricular folds were directly observed because the
aryepiglottic folds were strongly constricted. Therefore, it is difficult to
prove whether the vocal and ventricular fold vibrate or not. However, we
conclude that the vocal and aryepiglottic folds vibrate and ventricular folds
do not. The basis of this conclusion is as follows.
Smooth
transition from modal to growl is frequently achieved by various singers and
the subjects, therefore, it is reasonable to claim that, in growl, the vocal
folds vibrate at almost opposite phases. To take account of the delay of the
sound to the EGG, we consider that the maximal excitation of sound and the
shape of the EGG waveform were mainly due to the vocal fold vibration. Next, if
all three folds had simultaneously vibrated, the phases of their vibration
would most likely have been different from each other by aerodynamically
constraint. However, it is difficult to ascertain this phenomenon from EGG
waveform alone. To verify our claim, it is necessary to directly observe the
movements of the three folds.
5. Acoustical analysis
Fig. 6 shows a spectrogram of
the growl voice. Subharmonics appeared in growl. Similar subharmonic
oscillation has been observed in kargyraa [4, 6, 9], and in some 
cases of vocal
fry [10]. Perceptual clarification of differences among these phonations is
important. Here, however, we focus on acoustical differences between growl and
kargyraa.
Fig. 7 shows
the power spectra and spectral envelopes of growl and kargyraa. In growl, the
range from above 2kHz has very weak power. Fig. 8 shows the inverse filtered source
and its power spectrum of growl and kargyraa.
In growl, a pole is observed
at about 1.5 kHz, whereas, in kargyraa, below 4 kHz, the power moderately decreases.
Physiologically,
generation of subharmonics is concluded to be caused by the vocal fold
vibration in vocal fry, ventricular fold vibration in kargyraa, and the
aryepiglottic vibration in
growl. In karygraa, the ventricular fold constriction contributes to the
generation of the laryngeal ventricle resonance, which appears as a zero in the
laryngeal source. In growl, the aryepiglottic constriction constructs a deeper
and larger cavity consisting of the laryngeal ventricle, ventricular fold
region, and laryngeal vestibule (Figs. 1, 3, 4). Therefore, the resonance frequency
of the cavity must be lower than that of the laryngeal ventricle. Fig. 9 shows
the spectra of the synthesized laryngeal source obtained using the two-by-two mass
model [8]. For simplicity, the aryepiglottic and ventricular fold vibration and
vocal tract are omitted. The pole in the source of growl is at about 1.5 kHz
and is lower than in kargyraa.
We also
roughly calculated the resonance frequencies of the laryngeal ventricle for
kargyraa and the laryngeal cavity for growl by using a Helmholtz resonator. In
kargyraa, we assume that the body cylinder (the laryngeal ventricle) has 0.4cm
height and 1.5cm squared area and the neck cylinder (the ventricular fold
region) 0.8cm height and several areas. In growl, we assume the body has 2.0 cm
height and a 1.02cm squared cross-sectional area, and the neck (the
aryepiglottic area) 0.4 cm height and several areas (Table 1). If the
constricted regions have equal area, the resonance frequency of the source in
growl is always lower than that in kargyraa.
6. Discussions and conclusions
In growl, the larynx position
is higher than in the modal case, and the aryepiglottic region is strongly
approximated.
The
aryepiglottic folds vibrate, as well as vocal folds, and contribute to the
subharmonic oscillation. The resonance frequency of the cavity induced by the aryepiglottic
constriction is lower than that of the laryngeal ventricle, and this
characterizes the growl voice.
The
mechanism of the supraglottal constriction is still controversial. The
supraglottal constriction is widely considered to be caused by an activity of
the aryepiglottic muscle, however, from our physiological observations and
previous histological observation of the supraglottal muscles [5], the
constrictions of the aryepiglottic and ventricular folds are presumably caused
by different mechanisms.
The
power of the subharmonics in growl is seemingly lower than in kargyraa, but
further analysis is needed to clarify this. Perceptual evaluation of
differences among various subharmonic phonations, such as growl, kargyraa, and
vocal fry, will be addressed as future work. Analysis of other perceptually
similar singing styles, such as Sardinian singing, will also be addressed as
future work.
Acknowledgments
We thank Samuel Araujo,
Parham Mokhtari, Seiji Niimi, Makoto Ogawa, Satoshi Takeuchi, and Mamiko Wada
for their helpful discussions.
References
[1] S. Ara´ujo and L. Fuks.
Pr´acticas vocais no samba carioca: un di´alogo entre a ac´ustica musical e a
etnomusicologia, In N. M. Claudia and T. M. Refnanda and T. Elizabeth Ed., Ao
encontro da Palavra Cantada: poesia, m´usica e voz, pp.278–288, Viveiros de
Castro Ltda., 2001.
[2] J. C. Catford. Fundamental
Problems in Phonetics,
[3] J. H. Esling. Pharyngeal
consonants and the aryepiglottic sphincter, J. International Phonetics
Association, 26(2):65–88, 1996.
[4] L. Fuks, B. Hammarberg,
and J. Sundberg. A self-sustained vocalventricular phonation mode: acoustical,
aerodynamic and glottographic evidences, KTH TMH-QPSR,3/1998:49–59, 1998.
[5] M. Kimura, K.-I.
Sakakibara, H. Imagawa, R. Chan, S. Niimi, and N. Tayama. Histological
investigation of the supra-glottal structures in human for understanding
abnormal phonation, J. Acoust. Soc. Am., 112:2446, 2002.
[6] P.-A° . Lindestad, M.
Sodersten, B. Merker, and S. Granqvist. Voice Source Characteristics in
Mongolian “Throat Singing” Studied with High-Speed Imaging Technique, Acoustic
Spectra, and Inverse Filtering, J. Voice, 15(1):78–85, 2001.
[7] J. J. Pressman.
Sphincters of the larynx, A. M. A. Arch. Otolaryngol., 59(2):221–236, 1954.
[8] K.-I. Sakakibara, H.
Imagawa, S. Niimi, and
[9] K.-I. Sakakibara, T.
Konishi, K. Kondo, E. Z. Murano, M. Kumada, H. Imagawa, and S. Niimi. Vocal
fold and false vocal fold vibrations and synthesis of kh¨o¨omei, Proc. of ICMC
2001, 135–138, 2001.
[10] R. L. Whitehead, D.
[11] H. Zemp, Ed. Les Voix du
Monde — Une anthologie des expressions vocales. 3 vol. CDs with book, CMX374
1010.12, CNRS/Mus´ee de l’Homme, 1996.
Return to Mongolian
Khoomii Singing main Page