A discriminative analysis within and across voiced and unvoiced consonants in neutral and whispered speech in multiple indian languages

Whispered speech lacks the vocal chord vibration which is typically used to distinguish voiced and unvoiced consonants, making their discrimination a challenging task. In this work, we objectively and subjectively quantify the amount of discrimination between a voiced (V) consonant and its unvoiced (UV) counterpart using seven V-UV consonant pairs in six Indian languages, in neutral and whispered speech. We also quantify the extent to which the voicing characteristics in a consonant changes from neutral to whispered speech. Experiments using vowelconsonant-vowel (VCV) stimuli demonstrate that the V-UV discrimination reduces from neutral to whispered speech in a consonant specific manner with highest reduction for /g/-/k/ pair and least reduction for /z/-/s/ pair. Interestingly, this reduction in objectively measured discrimination does not directly correlate with the reduction in the V-UV classification accuracy obtained from subjective evaluation. Results from listening test show that the maximum and minimum reduction in the V-UV classification accuracy occur for /Ã/-/Ù/ and /v/-/f/ pairs when whispered. Whispered Tamil and Telugu VCV achieve the highest (85.71%) and lowest (58.93%) subjective V-UV classification accuracy respectively, demonstrating the variability in the production and perception whispered consonants across languages.