Some Cues for the Distinction Between Voiced and Voiceless Stops in Initial Position

Experiments with synthetic speech produced by the Pattern Playback indicated that the voiced stops in initial position could be made to sound like their voiceless counterparts by cutting back the beginning of the first-formant transition. Normally, the cutback of the first formant raises its starting frequency and also delays the time at which it begins relative to the other two formants. Both these changes appeared, in general, to be necessary. With certain combinations of stop and back vowel, however, a delay in the onset of the first formant was by itself sufficient to produce a strong voiceless effect. Substituting noise for harmonics in the transitions of the second and third formants (for the duration of the first-formant cutback) increased the impression of voicelessness over that obtained with cutback alone. In judging stimuli that lay near phoneme boundaries, many listeners demonstrated what appeared to be a very high degree of acuity. It is possible that this is the result of long experience in the use of the language and thus represents an effect of learning on perception.