Date of Award
Doctor of Philosophy (PhD)
Speech and Hearing Science
Mary L. Erickson, Ph.D.
Daniela Corbetta, Ph.D. Mark Hedrick, Ph.D. Kristin A. King, Ph.D.
Research has shown that singers are better able to match pitch when the target stimulus has a timbre close to their own voice. This study seeks to answer the following questions: 1. Do classically trained female singers more accurately match pitch when the target stimulus is more similar to their own timbre? 2. Does the ability to match pitch vary with increasing pitch? 3. Does the ability to match pitch differ depending on whether the target stimulus is produced with or without vibrato? 4. Are mezzo sopranos less accurate than sopranos? Stimuli: Source signals were synthesized with a source slope of -12dB/octave using vibrato and without vibrato at each of the frequencies, C4, B4 and F5. These source signals were filtered using 5 formant patterns (A-E) of vowel /a/ constituting a total of 30 stimuli (5 formant patterns*3pitches*2 vibrato conditions). Procedure: Ten sopranos and 10 mezzo-sopranos with at least 3 years of individual voice training were recruited from the University Of Tennessee School Of Music and the Knoxville Opera Company. Each singer attempted to vocally match the pitch of all 30 stimuli presented twice in a random order. Analysis and results: Pitch matching accuracy was measured in terms of the difference in cents between the target and the experimental productions at two locations, (1) pre-phonatory set (2) mid-point of the vowel. Accuracy of pitch matching was compared across vibrato and nonvibrato conditions. Results indicated that there was no significant effect of formant pattern on pitch matching accuracy. With increasing pitch from C4 to F5, pitch matching accuracy increased in mid-point of the vowel condition but not in pre-phonatory set condition. Mezzosopranos moved towards being in tune from pre-phonatory to mid-point of the vowel. However, sopranos at C4, sang closer to being in tune at pre-phonatory, but lowered the pitch at the midpoint of the vowel. Presence or absence of vibrato did not affect the pitch matching accuracy. However, the interesting finding of the study was that singers attempted to match the timbre of stimuli with vibrato. Results are discussed in terms of interactions between pitch and timbre from auditory perceptual as well as physiological point of view and how current theories of pitch perception relate to this phenomenon. Neither physiological nor auditory perceptual mechanisms provide complete explanations for the results obtained in the study. From a perceptual point of view, an interaction between pitch and timbre seems to be more complex, for spectral and temporal theories are limited in explaining these interactions. Also, possible explanations for the phenomenon of timbre matching are provided.
Duvvuru, Sirisha , "The Effect of Timbre and Vibrato on Vocal Pitch Matching Accuracy" (2012). Theses and Dissertations (ETD). Paper 71. http://dx.doi.org/10.21007/etd.cghs.2012.0076.