Effects of native language on perception of the relative amplitudes of the first and second harmonics.

As an incidental result of previous studies of the perception of spectral slope, we found that Mandarin speakers were nearly twice as sensitive to changes in the amplitude of the first harmonic relative to the second (H1-H2) as are English speakers. Although two Mandarin tones are typically produced with characteristic changes in voice quality, Mandarin does not contrast phonation types directly. Thus, the observed difference between listener groups could be due to increased attention to overall source characteristics in speakers of tone languages (because F0=H1), or specifically to experience with voice quality differences apart from F0. To clarify this matter, we measured just-noticeable differences in H1-H2 for speakers of Gujarati, a non-tonal language that contrasts breathy and modal vowels in H1-H2, and for speakers of a language like Yoruba that contrasts tones but not phonation types. If increased sensitivity to H1-H2 differences is due to attention to H1, then just-noticeable differences for both groups should be smaller than those for English speakers. However, if perceptual experience specifically with the H1-H2 contrast is required, then Gujarati speakers, but not Yoruba speakers, should show increased sensitivity relative to English speakers. [Research supported by NIH and NSF.]