Vibrato and pitch transitions

Journal of Voice Vol. 1, No. 2, pp. 157-161 © 1987 Raven Press, New York

Special Topic: Vibrato

Vibrato and Pitch Transitions Denise Myers and *John Michel School of Fine Arts, Department of Music and Dance and *Department of Speech-Hearing-Language, University of Kansas, Lawrence, Kansas, U.S.A.

Summary: There are at least two timing variables to be considered in vocal music performance. The first is the note changes associated with the meter signature (4/4, 2/4, etc.) and the second is the vibrato rate of the performer. Because the probability is not great that these two temporal variables will always be in perfect synchrony, it was the purpose of this investigation to determine what singers do when these two timing variables come into conflict during singing. Six singers recorded a series of alternating upward and downward interval shifts of a third while singing whole notes, half notes, quarter notes and eighth notes. The same notes were then recorded with intervals of a fifth. The recorded samples were converted to a visual trace and examined for interactions between vibrato and meter. Analysis of the tracings indicated that, in the majority of the cases, the singers would alter their vibrato in order to adhere to the timing of the musical line. Key Words: Singing--Vibrato--Pitch changes--Timing.

notes should be, h o w long they should be (whole notes, half notes, quarter notes, eighth notes, etc.), and h o w loud they should be (fff, ppp) etc. When these two temporal or timing programs of vibrato and composition are combined, the probability that they will be in perfect s y n c h r o n y is not great. For example, what happens to that vibrato when the d e m a n d s of the music indicate that an increase in pitch is dictated w h e n the vibrato is on its downward swing or what h a p p e n s when a decrease in pitch is needed at the exact time the vibrato is going up? W h e n these conflicts occur, several options are o p e n to singers: (a) t h e y c a n l e a v e the v i b r a t o a l o n e - - n o t t r y to change i t - - a n d simply let it ride on the musical line; (b) they can alter by shortening or lengthening the n o t e to a c c o m m o d a t e the vib r a t o ; or (c) t h e y can alter b y slowing d o w n or speeding up the vibrato rate to a c c o m m o d a t e the musical line. The p u r p o s e of this investigation was to e x a m i n e what singers do w h e n these two timing p r o g r a m s c o m e into a p p a r e n t conflict.

Most singers consider vibrato to be a desirable element, o r n a m e n t , or characteristic to h a v e in their singing voices. It m a k e s the voice sound m o r e pleasing, alive, exciting, warm, and less mechanical than a straight or flat tone. M o s t r e s e a r c h has s h o w n and m o s t e v e r y o n e agrees that the usual rate of v i b r a t o - - d e f i n e d as periodic or regular fluctuations in frequency and int e n s i t y - - i s around 5 - 6 or 7 H z , that is, 5 - 7 cycles per second are the t e m p o r a l d e m a n d s or requirem e n t s f o r v i b r a t o . T h e r e are also t e m p o r a l demands and requirements in the musical literature to be performed. T h e r e are k e y signatures and timing directions (4/4, 2/4, 6/8, etc.), which tell the perf o r m e r s - a r t i s t s h o w the c o m p o s e r i n t e n d e d the c o m p o s i t i o n to sound: mainly w h a t the pitches/

Address correspondence and reprint requests to Dr. J. Michel, Department of Speech-Language-Hearing: Sciences and Disorders, 290 Haworth Hall, The University of Kansas, Lawrence, KS 66045, U.S.A.

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D. M Y E R S A N D J. MICH E L

METHOD

Subjects Six singers served as subjects for this study. There were 2 men (1 baritone and 1 tenor) and 4 women (1 lyric soprano, 1 lyric spinto soprano, and 2 lyric mezzo sopranos). They ranged in age from 20 to 42 years (individual ages were 20, 23, 24, 24, 35, and 42 years) and had studied from 1 to 15 years (1, 5, 7, 8, 12, 15 years, respectively). Five were graduate students in music, and one was an undergraduate student not majoring in music.

Singing sample Each subject recorded 16 singing samples. The first four samples were upward and downward skips of a third in whole notes (3), half notes (6), quarter notes (12), and eighth notes (16). The next four samples were upward and downward skips of a fifth in whole notes, half notes, quarter notes, and eighth notes (Fig. 1). These eight samples were then repeated for the total of 16 samples. The sub~1,..

jects were instructed to sing each sample or vocal line with an/ah/vowel. The intervals were in each subject's comfortable range and usually consisted of E to G for the third interval and E flat to B flat for the fifth interval. Each musical line was played on the piano for the subjects, and they were allowed to warm up if necessary. These sung samples were recorded in the regular voice studio of D.M. at the University of Kansas on a Luxman K-240 tapedeck through a Shure 555 dynamic microphone. Analysis procedure The recorded samples were converted to a visual trace on a Kay Elemetrics model 6087 Visipitch and examined by both of us for interactions between vibrato and the musical notation. RESULTS Prior to numerical analysis, the traces were examined visually to determine the existence of any

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sung by each subject. The are pitch changes of a third, half notes, quarter notes, and second four samples are pitch with the same notes.

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FIG. 2. W h o l e note changes of a fifth. A: Vibrato being carried upward with the ascending pitch. B: I n s t a n c e s of pitch stabilization after a change in pitch and before bringing in the vibrato.

obvious phenomena. For example, in Fig. 2 the circled area A shows a point at which the downward portion of the vibrato cycle was interrupted by the upward movement of the musical line. The two points marked B reflect a period of "stabilization" during which the singer appeared to establish the pitch of the note firmly before adding the vibrato. In Fig. 3, the circled areas A again show the point at which the downward movement of the vibrato was interrupted by the change in pitch. The vibrato did not stop but appeared to "ride" on the pitch change. The downward pitch change also appears to have the vibrato riding on it, as shown by circles B in Fig. 3. Figure 4 shows the vibrato riding on the downward pitch changes much more clearly than on the upward changes. The first 4 top notes have 3 dis-

FIG. 4. Quarter note c h a n g e s of a fifth. The vibrato and the musical line s e e m to be s y n c h r o n i z e d in s u c h a w a y that the downward pitch changes carry the vibrato.

tinct vibrato cycles whereas the fifth has 4, with the top notes being considerably more even and regular than the bottom notes. The bottom notes were uneven in that the downward pitch change does not always reach the tonic and the vibrato configuration seemed uneven and inconsistent. Figure 5 shows fairly clearly that there were two vibrato cycles at each top note and almost none on the bottom or tonic note. The phonation in Fig. 6 shows the vibrato riding on both the upward (A) and downward (B) pitch change areas. Again, the upper notes appear to be more stable than the lower notes in that the number of vibrato cycles is more consistent on the top than on the bottom. In Figs. 7 and 8, the indistinct changes in pitch

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FIG. 3. Half note changes o f a fifth. A: Vibrato being carried on an ascending pitch. B- Vibrato being carried on the descending pitch.

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FIG. 5. Quarter note c h a n g e s of a fifth. This phonation appears to be characterized by a fairly clear two-cycle vibrato on the top n o t e s a n d almost no vibrato on the tonic or lower note. The top note also s e e m s to be " m o r e i m p o r t a n t " than the tonic as it is m o r e distinct and of longer duration.

Journal o f Voice, Vol. 1, No. 2, 1987

160

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A N D J. M I C H E L

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FIG. 6. Half note changes of a third. A: Vibrato riding on an upward pitch. B: Vibrato riding on a downward pitch.

m a y be t h e r e s u l t o f t h e s i n g e r ' s d i f f i c u l t y in resolving the "priority" question between vibrato a n d t h e m u s i c a l line; t h a t is, the v i b r a t o a n d t h e m u s i c a l l i n e a p p e a r to b e g e t t i n g in e a c h o t h e r ' s way. T h e t o p n o t e in Fig. 8 c h a n g e s f r o m 2 v i b r a t o c y c l e s in t h e first 6 n o t e s to 3 c y c l e s in t h e l a s t 2. T h e t o p n o t e s d o , h o w e v e r , a p p e a r to b e m o r e on p i t c h (flatter) t h a n t h e b o t t o m o r t o n i c n o t e s , w h i c h are quite uneven and irregular even though each b o t t o m n o t e a p p e a r s to h a v e 2 v i b r a t o c y c l e s . F i g u r e 9 s h o w s a r a t h e r c o n s i s t e n t f o u r - c y c l e vibrato on the lower or tonic notes and a five-cycle v i b r a t o o n t h e t o p n o t e s e x c e p t for the f o u r t h t o p n o t e , w h i c h a p p e a r s to b e s h o r t e r in d u r a t i o n t h a n t h e o t h e r s a n d o n l y h a s v i b r a t o c y c l e s . It is u n c l e a r w h e t h e r a n y o f t h e s e v a r i a t i o n s m a y b e d u e to r e s o -

FIG. 8. Eighth note changes of a third. This phonation has a suggestion of regularity on both the top and tonic notes. There are 2 vibrato cycles on the first 6 top notes and 3 on the last 2. If turned upside down, the tonic shows 3 vibrato cycles throughout. lution difficulties between vibrato and the musical line. F i g u r e 10 a p p e a r s to b e a f a i r l y c o m m o n e x a m p l e o f t h e v i b r a t o riding o n t h e m u s i c a l line. T h e r e is a c o n s i s t e n t t h r e e - c y c l e v i b r a t o o n t h e t o p n o t e exc e p t f o r t h e f o u r t h n o t e , w h i c h is p r o b a b l y t h e result o f a l o s s o f c o n c e n t r a t i o n b y t h e singer; the b o t t o m o r t o n i c n o t e s a p p e a r to h a v e t w o c y c l e s of vibrato. T h e p h o n a t i o n in Fig. 11 is o n e in w h i c h t h e vib r a t o r a t e a n d t h e t i m i n g r e q u i r e m e n t s o f t h e musical line a r e in r e a s o n a b l e s y n c h r o n y , as e v i d e n c e d b y t h e e v e n n e s s o f b o t h t h e t o n i c a n d the t o p lines, b y t h e s a m e n u m b e r o f v i b r a t o c y c l e s o n t h e top a n d b o t t o m n o t e s , a n d b y t h e s a m e r e l a t i v e durations of both the top and bottom notes.

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FIG. 7. Quarter note changes of a third. Examples of vibrato riding on both upward (A) and downward (B) pitch changes. There are four vibrato cycles in the first 4 top notes and five in the last 2. The tonic looks somewhat uneven until it is turned upside down, showing that it too has a pattern similar to that of the top note.

Journal o f Voice, Vol. 1, No. 2, 1987

FIG. 9. Quarter note changes of a fifth. This is a very regular phonation with a fairly consistent four-cycle vibrato on both the top and tonic notes. The notes also appear to be of the same duration, with the pitch change carrying no vibrato.

VIBRATO A N D P I T C H T R A N S I T I O N S

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FIG. 10. E i g h t h note c h a n g e s of a fifth. In this p h o n a t i o n , there is a fairly regular three-cycle vibrato on the top n o t e s except for the fourth note, w h e r e the singer m a y have lost control and concentration. T h e tonic also a p p e a r s to be s o m e w h a t regular, w i t h a two-cycle vibrato.

F I G . 11. Q u a r t e r n o t e c h a n g e s of a fifth. T h i s p h o n a t i o n is s o m e w h a t u n u s u a l in that the vibrato o n the tonic notes a p p e a r s to be m o r e c o n s i s t e n t t h a n the vibrato on the top notes. The n o t e s are also very regular, w i t h an a l m o s t equal duration for all the notes.

Based on these preliminary observations, some tentative conclusions may be offered:

ciding which timing program to follow when making a pitch change.

1. The temporal aspects of vocal vibrato appear to be mainly independent of the musical line of the composition. 2. The top note of a series of up and down pitch changes seems to be most important to the performer, that is, it receives more " a t t e n t i o n , " more precision. 3. Interruptions of or absence of vibrato tends to occur more on the bottom note than on the top note. The top note appears to be considered to have higher priority. 4. A period of stabilization--no v i b r a t o - - a f t e r a pitch change suggests that intonation has a higher priority than vibrato. 5. The rate of vibrato appears to increase as the notes in a pitch change b e c o m e shorter, i.e., whole note, half note, quarter note, and eighth note. 6. S o m e singers seem to have difficulty in de-

We are currently developing computer programs to make more precise measurements of parameters such as the duration of each note, the number of v i b r a t o cycles per n o t e , the speed of the pitch change, the accuracy of the pitch change, the duration of the stabilization period, etc. We will also be able to examine the interrelationships among these variables. The question we have not addressed, and hesitate to do so, is whether it really matters if the vibrato is modified or interrupted by the musical line. We found that as we listened more and more carefully, we started to " t u n e in" to the effects of some of these vocal behaviors of the subjects and were able to tell when a vibrato was interrupted or changed. Although this tuning-in provided us with another behavior to listen for, the final decision as to the importance of these behaviors will ultimately lie with the teachers, the performers, and the audiences.

Journal of Voice, Vol. 1, No. 2, 1987