Perception of vowel quality in the presence of other sound sources

Abstract

If the energy of a harmonic (500 Hz) near the first formant of a vowel is increased, the vowel quality changes. But if the tone corresponding to this increase in energy starts or stops at a different time from the original vowel, then listeners can perceive the original vowel quality [Darwin, Attention and Performance, Vol. X (Erlbaum, 1983)] even though the spectrum present during the vowel is inappropriate. Listeners apparently partition the total sound present into separate percepts on the basis of onset‐ and offset‐time differences. The present experiments show that the same partitioning still occurs when the “original” vowel has reduced energy at 500 Hz. Now adding extra energy to it restores a normal vowel spectrum. Listeners report a vowel quality corresponding to the “original” depleted vowel when the additional energy starts or stops at a different time from the rest of the vowel, even though the spectrum present during the vowel is appropriate to a vowel with a normal spectral envelope. The partitioning of sound sources observed here cannot be explained by a tendency to perceive vowels with conventional spectral envelopes. [Work supported by SERC.]