Kaya no kiyama no kaya no miwa
Itsuka koborete inoarete
Yamaga no obasa wa iro ni mata
Sodataki shibataki akari tsuke
When a singer sings a song, he changes pitch, intensity, and or quality of the voice appropriately as music goes on.
The regulation of the voice is carried out by the muscles of the respiratory,
phonatory, and articulatory organs. This film presents the results of experimental studies
with five professional singers chiefly related to the function of the phonatory organ,
namely the larynx, which directly regulates the vocal parameters.
Vocal chord vibration of two different registers at the same pitch level will be shown in ultra high
speed cinematography. The pitch is C4. The first scene shows vibration in heavy register, mid-voice.
In mid-voice, the vocal chord is thick and the wave-like movement on the mucosa is remarkable.
Complete glottal closure takes place and the close phase is long. The vocal chord movement
is rather complicated.
Let us see the movement in stop motion.
Let us see the movement again while listening to the voice.
Next, a tone of the same pitch level is sung in light register, falsetto.
In falsetto, the vocal chord is thin. The wave-like movement of the mucosa is poor
and there is no complete closure of the glottis. The vocal chord movement is rather simple.
Let us see the movement in stop motion.
Now let us see the movement again listening to the voice.
What makes the differences in vibration? We investigated laryngeal muscles electromuographically.
The most remarkable difference between the two registers is found in the vocalis muscle.
The vocalis muscle presents marked activity in mid-voice while it shows little activity in
falsetto. Powerful contraction of the vocalis muscle results in a thick vocal chord,
remarkable mucosal wave, and forceful closure of the glottis. The cricothyroid and lateral
cricoerotinoid muscles also show greater activity in mid-voice, however not so markedly as the
vocalis. Activity of laryngeal muscles for different registers at the same pitch level
is compared in each singer. The degree of activity is shown in rank order.
In all the subjects, the heavier the register, the greater the vocalis activity is.
A similar tendency is found in the lateral cricoerotinoid and intererotinoid muscles,
although it is not so consistent and pronounced as in the vocalis muscle.
The cricothyroid muscle presents no consistent relationship to the vocal register. Next,
a change in muscular activity will be shown when the register is changed during singing.
A phrase shown here is sung in two different ways. First it is sung in heavy register throughout
and then the register is shifted to falsetto in the posterior part. When sung in heavy register
throughout, marked vocalis activity continues. Activity of the cricothyroid, lateral cricoerotinoid
and vocalis muscles is pronounced throughout and is parallel to the pitch.
When sung with a register change, activity of the vocalis muscle almost disappears in falsetto.
Among the three laryngeal muscles investigated,
a change in activity for the register shift is found most pronounced in the vocalis muscle.
Air flow rate is increased for falsetto as shown in the lower figure.
In a yodel, abrupt alternating changes between the heavy voice and the falsetto take place, like this.
Activity of the vocalis muscle is markedly weakened in falsetto, the underlying parts.
Activity of the cricothyroid muscle becomes greater as the pitch is raised. This indicates
that the cricothyroid muscle is essentially a pitch agent. There is no remarkable difference
in activity of the lateral cricoerotinoid muscle between the two registers.
An increase in the activity for high pitch seems to be balanced by a decrease for falsetto.
This table shows changes in muscular activity in response to register shift during singing.
About 480 samples in total uttered by the five singers were investigated.
The vocalis muscle shows a marked change in activity whenever a clear register shift occurs.
The lateral cricoerotinoid and intererotinoid present a similar tendency, but less consistently
than the vocalis. The cricothyroid often shows no marked change. Let us now summarize.
One, the vocal register is primarily regulated by the vocalis muscle, which contracts more
powerfully for a heavier register. Two, the lateral cricoerotinoid and intererotinoid muscles
contract more powerfully for heavier registers assisting the vocalis muscle. Three, the cricothyroid
muscle shows no systematic relationship to the register. However, since it has an antagonistic
function to the vocalis muscle, it should influence the vocal register. Let us now discuss pitch
regulation. A three octave descending scale is sung by a soprano, starting with falsetto
or light head voice and shifting to mid, then chest voice.
In heavy registers such as mid and chest, activity of all three muscles is decreased as the pitch
becomes lower. In light register, however, no remarkable changes are found in muscular
activity associated with pitch changes. These electromyographic recordings suggest that
regulatory mechanism of pitch is different according to vocal register. Next, activity
of the intererotinoid muscle is shown. Activity of the intererotinoid muscle is greater for
higher range in both registers, light and heavy, but it does not present a gradual decrease
with falling pitch, which is observed in the lateral cricoerotinoid. Let us listen again.
The results from the five singers are summarized in this table. In heavy register, activity
of the cricothyroid, lateral cricoerotinoid, and vocalis muscles is always positively related
to pitch. In light register, such as falsetto and light head, activity of these muscles
is not always related to pitch. Other factors are also thought to participate in regulating
pitch in light register. The intererotinoid muscle shows marked activity only for the
higher range in each register. There is no doubt that contraction of the cricothyroid
muscle stretches the vocal cord and makes it elongated and thin, resulting in an increase
in pitch. The lateral cricoerotinoid, vocalis, and intererotinoid muscles adduct the vocal
cord. It has also been proved experimentally by many investigators that an increase in
the adducting force can cause an increase in pitch. Besides the direct influence of
the adductor's activity upon the pitch, the increase in the adductor's activity with
rising pitch seems significant for other reasons. When the cricothyroid muscle is activated
to raise the pitch, the vocal cord is stretched. The edge of the vocal cord tends to be placed
along the line between the posterior cricoerotinoid ligament and the anterior commissure. Therefore,
the cricothyroid muscle has the function of abducting the vocal cord, which is in the
medium position. This must be compensated for by the adductor muscles in order to keep
the vocal cord in a position appropriate to the vibration. Furthermore, the cricothyroid
muscle has antagonistic functions to the vocalis, as shown here. If the activity of the cricothyroid
muscle is increased without an increase in that of the vocalis, vocal register will become
lighter. A simultaneous increase in vocalis activity is necessary for maintaining the
register constant. Let us summarize. One, the cricothyroid muscle regulates the pitch
directly. An increase in its activity results in a rise in pitch. Two, activity of the lateral
cricorotinoid and vocalis muscles is increased with the increasing pitch. This is significant
not only for raising pitch, but also for maintaining adequately the position of the vocal cord
and register. Three, participation of these three muscles in regulating pitch is more
dominant in heavy register than in light register. Four, the interaerotinoid muscle participates
in regulating pitch only in the higher range of each register. In order to investigate
the regulatory mechanism of vocal intensity, first let us look at the muscular activity
during singing swell tones. The swell tone is a sustained tone at a given pitch with
increasing intensity, or crescendo, followed by decreasing intensity, that is decrescendo,
sung in this way. This figure presents muscular activity schematically when a bass singer
sings swell tones at various pitches and in various registers. At a low pitch in heavy
register, activity of the lateral cricorotinoid and vocalis muscles is positively related
to vocal intensity. At a higher pitch, even in heavy register, activity of the lateral
cricorotinoid muscle is not related to intensity anymore, although that of the vocalis muscle
is still positively related. Activity of the cricothyroid is negatively related to intensity.
In light register, at the same pitch, activity of the vocalis muscle is not related to intensity
either. At a higher pitch in light register, activity of all the muscles shown here are
negatively related to intensity. A similar tendency was found in other singers. The
results suggest that the vocal intensity is regulated chiefly by the adductor muscles
at low pitches in heavy register, whereas in high falsetto, it is regulated chiefly
by some other parameter, probably by the air flow rate. Air flow rate is increased with
crescendo in both registers. Especially in light register, the increase in air flow rate
with increasing intensity is significant, and the air flow curve is almost completely
parallel to the intensity. In heavy register, the air flow rate is less closely related
to intensity. Activity of the cricothyroid muscle lessens with increasing intensity.
Since changes in the parameters which cause an increase in intensity can result in simultaneous
rise in pitch, the cricothyroid muscle should be relaxed to some extent in order to keep
the pitch constant. The decrease in the cricothyroid activity is reflected in a shortening of the
vocal cord length. Now let us look at the vibration of the vocal cord when soft and
loud tones are sung in different registers. In a soft, heavy voice, the vocal cord is
rather thick. The glottis is closed completely. Although the amplitude of vibration is small,
there is considerable wave-like movement of the mucous membrane. The voice sounds like
this. In loud phonation in heavy register, the amplitude of vibration is great, and mucosal
wave is very pronounced. The vocal cord presents very dynamic movements. The voice is like
this.
In soft phonation in light register, the vocal cord is thin, the amplitude is small, the
mucosal wave is poor, and the posterior part of the glottis is not closed completely. The
closed time of the membranous portion is short. Here is the voice.
When the voice becomes louder in light register, the amplitude becomes greater. The mucosal
wave, however, is poor. The glottis is not closed completely. The voice is like this.
The regulatory mechanism of vocal intensity is summarized as shown here. One, in heavy
register, vocal intensity is regulated more dominantly by the vocalis and lateral cricoerotinoid
muscles. Two, in light register, intensity is chiefly regulated by the airflow rate.
Three, the intererotinoid muscle shows no remarkable participation in regulating intensity.
Four, the cricoerotinoid muscle presents compensatory action in order to keep the pitch adequate.
So far, the regulatory mechanism of register, pitch, and intensity of voice has been discussed
separately. However, these parameters are not independent, but are interdependent in
human beings. Register and pitch are related in the following way. As the activity of the
cricoerotinoid muscle becomes forceful, resulting in a rise in pitch, the effect of the vocalis
muscle antagonistic to the cricoerotinoid becomes smaller. Thus, the register tends
to become light. In the same way, when pitch comes down, register tends to become heavy.
Register and intensity are related in the following way. When the activity of the adductor
muscles becomes forceful, resulting in an increase in intensity, the register also tends
to become heavy. In the same way, as intensity becomes small, register tends to become light.
In actual singing, the various parameters of voice are changed simultaneously in complicated
ways. The laryngeal muscles must function quickly and precisely in close cooperation
with the respiratory and articulatory muscles.
The laryngeal muscles must function quickly and precisely in close cooperation with the
respiratory and articulatory muscles. The laryngeal muscles must function quickly and precisely
in close cooperation with the respiratory and articulatory muscles.
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