Sinewave vowel sounds: The role of vowel qualities, frequencies and harmonicity of sinusoids, and perceived pitch for vowel recognition

Abstract

In the literature, the recognition of sinewave vowels replicating statistical formant patterns is reported as impaired when compared to natural sounds. However, the corresponding formant simulating sinusoids were harmonically unrelated, with synthesised signals only accidentally being quasi-periodic, and vowel confusion was indicated to relate to vowel height. Involving five phonetic expert listeners, the present study tested vowel and pitch recognition of three sinusoid replicas based on statistical F1-F2-F3 patterns of the Standard German closed and mid-open vowels /i-y-e-ø-o-u/ for women, “corrected” approximations of these patterns with harmonically related sinusoids, and harmonical patterns with fixed first and third sinusoids, yet varying only the second sinusoid so as to effect a change in harmonic relation. The results showed strong vowel confusions for mid-open but only limited confusions for closed vowels. Additional effects on vowel recognition were indicated to concern harmonicity and specific frequencies of the sinusoids, and perceived pitch (range recognised = 165-440Hz). Thus, sinewave replications of formant frequencies seem to represent perceived vowel qualities not per se but only in relation to specific vowel qualities, sinusoid configuration and pitch, supporting earlier claims of spectral representation of vowel quality as being non-systematic and pitch-related.