EFFECTS OF FIRST FORMANT ONSET FREQUENCY ON [-VOICE] JUDGMENTS RESULTFROM AUDITORY PROCESSES NOT SPECIFIC TO HUMANS

When F1-onset frequency is lower, longer F1 cutback (VOT) is required for human listeners to perceive synthesized stop consonants as voicele ss. K. R. Kluender [J. Acoust. Soc, Am, 90, 83-96 (1991)] found compar able effects of F1-onset frequency on the ''labeling'' of stop consona nts by Japanese quail (coturnix coturnix japonica) trained to distingu ish stop consonants varying in F1 cutback. In that study, CVs were syn thesized with naturallike rising F1 transitions, and endpoint training stimuli differed in the onset frequency of F1 because a longer cutbac k resulted in a higher F1 onset. In order to assess whether earlier re sults were due to auditory predispositions or due to animals having le arned the natural covariance between F1 cutback and F1-onset frequency , the present experiment was conducted with synthetic continua having either a relatively low (375 Hz) or high (750 Hz) constant-frequency F 1. Six birds were trained to respond differentially to endpoint stimul i from three series of synthesized /CV/s varying in duration of F1 cut back. Second and third formant transitions were appropriate for labial , alveolar, or velar stops. Despite the fact that there was no opportu nity for animal subjects to use experienced covariation of F1-onset fr equency and F1 cutback, quail typically exhibited shorter labeling bou ndaries (more voiceless stops) for intermediate stimuli of the continu a when F1 frequency was higher. Responses by human subjects listening to the same stimuli were also collected. Results lend support to the e arlier conclusion that part or all of the effect of F1 onset frequency on perception of voicing may be adequately explained by general audit ory processes. Implications concerning VOT variation for stop consonan ts at different places of articulation or preceding different vowels a re discussed.