Vocalic correlates of pitch in whispered versus normal speech

In whispered speech, the fundamental frequency is absent as a main cue to pitch. This study investigated how different pitch targets can acoustically be coded in whispered relative to normal speech. Secondary acoustic correlates that are found in normal speech may be preserved in whisper. Alternatively, whispering speakers may provide compensatory information. Compared to earlier studies, a more comprehensive set of acoustic correlates (duration, intensity, formants, center-of-gravity, spectral balance) and a larger set of materials were included. To elicit maximal acoustic differences among the low, mid, and high pitch targets, linguistic and semantic load were minimized: 12 native Dutch speakers produced the point vowels (/a, i, u/) in nonsense vowel-consonant-vowel targets (with C = {/s/, /f/}). Acoustic analyses showed that in addition to systematic changes in formants, which have been reported before, also center of gravity, spectral balance, and intensity varied with pitch target, both in whispered and normal speech. Some acoustic correlates differed more in whispered than in normal speech, suggesting that speakers can adopt a compensatory strategy when coding pitch in the speech mode lacking the main cue. Speakers furthermore varied in the extent to which particular correlates were used, and in the combination of correlates they altered systematically.