Dept. for Speech, Music and Hearing

Quarterly Progress andStatus Report

Data on maximum speed ofpitch changes

Sundberg, J.

journal: STL-QPSRvolume: 14number: 4year: 1973pages: 039-047

http://www.speech.kth.se/qpsr

STL-QPSR 4/1973

B. DATA ON MAXIMUM SPEED O F PITCH CHANGES

J. Sundberg

Abstract

The maximum speed of voice pitch changes is measured in male and female s ingers and untrained subjects. Typical differences a r e observed between each of these four groups. On the average s ingers change the pitch m o r e quickly a s compared with untrained subjects. The same observation i s made regarding female subjects a s compared with male subjects. Unlike s ingers , untrained subjects perform pitch drops considerably fas te r than pitch elevations. The implications with respect to the propert ies of the pitch changing mechanisms a r e discussed.

Introduction

Pitch changes can be regarded a s manifestations of the pitch regulat-

ing system and can be assumed to m i r r o r the propert ies of this system.

The character is t ics of pitch changes performed a s quickly a s possible

by untrained speakers have been examined by Ohala (1972) and Ohala

and Ewan (1972). Singers can be assumed to use the pitch regulating

system with maximal efficiency. Therefore, an investigation of maximal-

ly fast pitch changes in s ingers may complement our knowledge about the

system in various respects . The purpose of the present paper was to

collect data on the maximal speed with which pitch can be changed in

s ingers and untrained subjects of both sexes.

Subjects-

The untrained subjects (six females , five males) participated in a one-

week voice training course. None of the subjects had abnormal voices,

and some of them had had modest experience singing in a chor. The

trained subjects (four females , five males) represented a group of highly

experienced singers. All of them had had severa l yea r s of voice t rain-

ing, and most of them presently work a s ope r a and concert singer s.

Experimental procedure

The subjects were asked to al ternate repeatedly between two given

pitches, and thereby to perform the pitch changes a s rhythmically and

a s quickly a s possible. The rhythm periodicity was signalled to the

subjects in slightly differing ways: by the exper imenter ' s counting

combined with distinct hand movements, o r by clicks in e a r phones

STL-QPSR 4/1973

combined with flashes of a small lamp. In this way, the interval

singing resembled a legato performance of the sequence of notes

schematically indicated in Fig. 11-B- I . At least 8 repetitions of

each pitch change were secured from each subject. The intervals

sung were an octave, a fifth, a major third, and in some cases

a l so a major second. These intervals correspond to a frequency

ratio of 1:2, 1:1.5, 1:1.25, and 1:1.12, respectively. Each sub-

ject s tar ted a l l intervals f rom the same lower pitch which lay in

the lower par t of the subject ' s range. The signal was recorded on

tape.

Fig. 11-B - 1. Schematical representation of the interval singing.

-

Measurements

The fundamental frequency was measured by means of a low

pass fi l ter connected to a zero-crossing detector. The output was

regis tered on a n oscillograph using a paper speed of 100 mm/sec.

etc .

L

A typical example of the registrations is given in Fig. 11-B-2.

3 * * (I, d

In this figure the measurement of the transient durations i s a l so I

1 i l lustrated. In each sample the s t a r t and end frequencies were

determined. Those points on the curve that represented 1/8 and

a 0

7/8 of the difference between the s t a r t and end frequencies were

identified. The time interval separating these two points was de-

0 *

fined a s the response t ime in accordance with the procedure chosen

by Ohala and Ewan (1972). Thus, the response t ime is the t ime

needed by the subject in o rde r to produce 6/8 of the pitch change.

In most cases the s ingers displayed a vibrato, i. e. the quasi-

stationary frequencies showed a regularly oscillating value. In

these cases the s t a r t and end frequencies were defined a s the

STL-QPSR 4/1973

seems to suggest that the auditory feedback provides information of r e -

levance to the synchronization of vibrato speed and pitch changes. How-

ever , a l l subjects did not adjust the vibrato speed in accordance with the

given tempo. In some cases the vibrato simply disappeared o r the tempo

was not maintained.

Results

A s the response t ime in this experiment was defined in the same way

a s in the investigation of Ohala and Ewan (1972) , our resu l t s should be

comparable to the i rs . In Fig. 11-B-3 the averages f rom our group of un-

trained male subjects can be compared with the data given by Ohala and

Ewan which pertain to the same type of subjects. There may be a slight

tendency for our subjects to perform pitch elevations m o r e quickly.

However, this difference i s presumably due to the fact that in our m e a s -

urements each subject' s slowest transit ions were disregarded. Apart

f rom this small difference, the agreement between the two se ts of data

is good. This agreement supports the assumption that our group of un-

trained ma les was representative, and that the differences in the ex- ~ perimental procedures between the two investigations did not affect the

resul ts .

Fig. 11-B-4 compares the averages of the male and female group of

untrained subjects. Mainly, the two pa i rs of curves simply paral le l

each other. This implies that the female and ma le groups show a s im-

i l a r dependence of interval width, but the female group has the shorter

response t imes. In both groups the response t ime grows with interval

width, particularly in the case of rising intervals. Fur the r , the rising

intervals have slower response t ime values than falling intervals.

In Fig. 11-B-5 the female group of untrained subjects i s compared

with the averages pertaining to the individual female singers. Regarding

the rising intervals two differences can be observed between the groups.

F o r the s ingers the response t ime i s shor te r , and the dependence on

interval width i s slightly smaller . A s r ega rds the falling intervals the

differences between the groups a r e smal le r eventhough the s ingers show

somewhat shorter response t imes. Thus, in the case of female s ingers ,

the t rend to slow pitch r i s e s and rapid pitch drops is much l e s s pro-

nounced than in the group of untrained.

UNTRAINED MALES

RISING

INTERVAL WIDTH (semitones)

FALLING

Fig. 11-B-3. Response t i m e values given by Ohala & Ewan (1972) (points) and the ave r ages obtained fo r our g roup of untrained m a l e subjects . The b a r s r ep r e sen t the s ca t t e r in t e r m s of + one s tandard deviation.

200

150

-

-

UNTRAINED MALE AND FEMALE

4 6 8 10 12 4 6 8 10 12

l NTERVAL WIDTH (sernitones)

Fig . 11- B - 4 . Averaged response time values for untrained male (solid line) and female (dashed line) subjects.

FEMALE TRAINED Ai\iD UNTR/"+lli\lED

2 4 6 8 10 12 2 4 6 8 10 12

INTERVA L WIDTH (semitones)

Fig. 11-B-5. Response t ime of f ema le s i nge r s . Each symbol r e f e r s to a given subject . The solid l ines show the ave r age response time of the group of female untrained subjects .

STL-QPSR 4/1973

Fig. 11-B- 6 allows the corresponding comparison with respect to

male subjects. Evidently, considerable differences a r e found in the

dependence on interval width among the singers. However, a s in the

female voices, the average response t ime i s shorter in the s ingers than

i n the untrained subjects, particularly i n r is ing intervals .

In Fig. 11-B-7 the averages obtained f rom each of the four groups of

subjects m a y be compared. In r is ing intervals the s ingers have fas te r

transit ions and the response t ime grows l e s s with increasing interval

width. With falling intervals we observe that the s ingers seem to show

a somewhat grea ter dependence on interval width, and that female s ingers

have somewhat fas te r transit ions than untrained voices. In both types of

intervals the female subjects give shorter response t ime values than

male subjects. Thus, there seems to be differences in the response t ime

between all of the four groups included in this investigation: between

ma les and females , and between untrained subjects and s ingers .

Discussion

Recently Ohala (1972) and Ohala and Ewan (1972) have suggested an

explanation for the asymmetry in the response t ime between rising and

falling intervals. F i r s t , they in terpre t the rapid pitch drops a s an in-

dication that pitch i s lowered actively. Our resu l t s support the same

conclusion. Second, in o rde r to explain why larynx height and pitch show

an interdependence in several subjects, they suggest that a high larynx

tenses the vocal folds in a ver t ical dimension. To quote Ohala and Ewan:

"The difference in t ime taken to r a i se and lower pitch could be explained

if we could show that the anter ior-poster ior tensing mechanism was

fas tes t for raising pitch and the vert ical tensing mechanism fastest for

lowering pitch". Thus, according to these authors , the fas t performance

of pitch drops may possibly be explained if the pitch dependent ver t ical

movements of the larynx a r e taken into account.

In singing, pitch dependent shifts in larynx height probably cannot be

accepted. This assumption i s supported not only by an overwhelming

agreement on this point among singing teachers , but a l so by the fact that ! a high larynx position i s likely to distroy the "singing formant", which /

I evidently i s a desirable character is t ic of professional singing, the

soprano voice possibly excepted ( ~ u n d b e r g 1972 and 1974). Also, formal

MALE TRAINED AND UNTRAINED

INTERVAL WIDTH (semitones)

Fig. 11-B-6. Response t i m e of m a l e s i n g e r s . E a c h symbol r e f e r s t o a given subjec t . The solid l i nes show the a v e r a g e r e s p o n s e time of the group of m a l e un t ra ined subjec ts .

RISING FALLING I I I I I

120 - -

loo - - r .

INTERVAL WIDTH (semitones)

Fig. 11-B-7. Average response t ime of male (filled c i rc les ) and female (open circles) untrained subjects (dashed l ines) and s ingers (solid l ines).

STL-QPSR 4/1973 44.

measurements of the dependence of larynx height on pitch in professional

s ingers support the conclusion that this dependence decreases with the

singers ' skil l (Frommhold and Hoppe 1965). Nevertheless, s ingers

were observed to perform pitch changes fas te r than untrained subjects.

Thus, if larynx height i s causually related to the speed of pitch changes,

this relationship seems to be ra ther complex.

Pitch changes a r e due to movements in s t ruc tures in the larynx from

one given position to another given position. In most fast and voluntary

movements of human s t ruc tures from one given position to another, two

antagonistic muscle functions a r e involved. With respect to a specific

movement, one group plays the role of an accelerator : by contracting it

accelerate the s t ructures toward the target position. The other muscle

group plays the role of a decelerator: i t decelerates the moving t issue

so that i t stops a t the target position and does not pass it. The maximum

speed with which the s t ructure can be moved between two given positions

probably depends on severa l factors. Among these we may as sume that

the following a r e important for fast changes in the voice pitch. One i s

the force per unit of m a s s to be moved, that the muscles involved develop.

Probably, the force of the accelerator i s m o r e decisive to the maximal

speed of movement than the force of the decelerator . Another factor

must be the t ime constants characterizing the feedback system used for ~ controlling the position of the moving s t ructure. A third factor may be

the contraction range of the muscles involved a s compared with the

contraction minimally required for the actual movement.

These considerations may help u s to find hypothetical explanations to

the differences in response t ime values that have been found above. Let

u s s t a r t by considering the asymmetry between rising and falling intervals, I

An important pitch-raising muscle i s the crico-thyroideus, According 1 I

to some authors , pitch can be lowered by contracting the thyro-arytenoi-

deus la te ra l i s (van Riper and Irwin, 1958 , Zemlin,. 1968 , Lindqvist, 1972).

If this muscle i s assumed to lower the pitch, the narrowing of the larynx

tube opening typically occurring when pitch i s lowered can be explained.

Thus, according to Lindqvist (1972), this muscle not only shortens and i laxes the vocal folds, but a lso constricts the larynx tube. Therefore, i t

can be said to have the function of protecting the larynx and the lungs.

Protecting muscles can be assumed to be well developed and quick in

cl ., ' .

STL-QPSR 4/1973

operation because of their importance to vital functions, If so , the

thyro-arytenoideus la te ra l i s must be assumed to be well developed and

quick in operation in a l l subjects regardless of training. The cr ico-

thyroideus does not possess a protective function. Therefore we may

assume that this muscle may be developed by training. The differ - ence in response t ime between s ingers and untrained subjects i s much

l a rge r in pitch elevations than in pitch drops. If we as sume that the

strength of the accelerator i s m o r e important to the speed of the move-

ment than the decelerator strength, this difference between s ingers and

untrained subjects becomes under standable. I t would reflect the con-

sequences of an increase of the force per unit of m a s s to be moved

developed by the crico-thyroid muscle , the accelerator in pitch eleva-

tions. The sex differences in response t ime values m a y ve ry well be

due to the same effect. If so, we would expect to find a pitch regulating

system which develops m o r e muscle force per unit of m a s s to be moved

in females than in males .

The differences in response t ime may ve ry well be due to m o r e than

one thing. The feedback system used for controlling the "position"

along the pitch scale may differ between s ingers and untrained subjects.

We may as sume that untrained subjects re ly to a higher degree on a slow

auditory feedback system than s ingers do. Singers may re ly more on a

sor t of "muscle memory" developed during the training. They "remember"

how much and when the various muscles must contract in o rde r for the

pitch to go f rom one given value to another. This ability to explore and

memorize the function of a muscle system seems to be of grea t relevance

in other fo rms of music playing. F o r instance, unlike the l ea rne r , the

professional pianist does not need to follow the finger with h is eyes in 1 orde r to hit a far-lying note on the key-board. By experience developed

during practice he "knows" exactly how much and when the relevant

muscles shall contract. I t seems likely that this ability to memorize I muscle positions and contractions i s developed and used a lso in singing.

The ability may in par t be responsible for the differences between s ingers

and untrained subjects. However, i t d o t s not explain a l l differences.

F o r instance, i t does not explainwhy the response t ime differences a r e

greater in rising than in falling pitch intervals.

STL-QPSR 4/1973 46.

The importance of the contraction range of the relevant muscles to

the speed of pitch changes may be studied by varying the frequency level

of the intervals systematically within the subjects' range. Such ex-

periments were not included in the present investigation. Therefore

this question must be left open for future research . .

The vibrato i s frequently assumed to be due to a self-oscillation of

the pitch regulating system. The frequency of these oscillations would

then depend on the t ime constants inherent in the pitch regulating system.

But these same time constants also manifest themselves in the response

time of pitch changes. Therefore, an interrelationship between the speed

of the vibrato and the response time in pitch changes might be expected.

Our resul t s did not show any interrelationship of this kind, though. F o r

instance, in the experiments with varied tempi, the vibrato periodicity

changed, whereas the response time values remained essentially the

same. F r o m these data i t seems safe to conclude that the vibrato gen-

erating system is not identical in a l l pa r t s with the pitch regulating sys-

tem.

The explanations suggested above to the response time differences

between the groups of subjects a r e certainly speculative. This seems to

be an inevitable consequence of the limited knowledge that we possess

about the pitch regulating system. I t is likely that this knowledge will

increase substantially when models have been worked out for the system

which controls, adjusts, and generates the voice pitch.

Conclusions

The data collected in the present investigation indicate that there a r e i

typical differences between various groups of subjects regarding the I I transient t ime required to complete changes of the voice pitch. Female I

subjects perform pitch changes fas ter than 1 ~ 1 a l e subjects, and s ingers

change the pitch f a s t e r than untrained voices. In untrained voices, pitch I

I

elevations take longer t ime than pitch drops, whereas this difference is

much l e s s pronounced o r even absent in singers. The dependence of I

the response time on the interval width var ies considerably between sub-

jects. The general trend i s , however, that the response time increases

slightly with interval width, particularly in the case of untrained sub-

jects performing pitch elevations. Hypothetically, the differences between