Perception of vocal effort and distance from the speaker on the basis of vowel utterances
To appear in Perception and Psychophysics
The sound pressure level of vowels reflects several non-linguistic and linguistic factors: distance from the speaker, vocal effort, and vowel quality. Increased vocal effort also involves an emphasis of higher frequency components and increases in F0 and F1. This should allow listeners to distinguish it from decreased distance, which does not have these additional effects. It is shown that listeners succeed in doing so on the basis of single vowels if phonated, but not if whispered. The results agree with a theory according to which listeners demodulate speech signals and evaluate the properties of the carrier signal, which reflects most of the para- and extra-linguistic information, apart from those of its linguistic modulation. It is observed that listeners allow for between-vowel variation, but tend to substantially underestimate changes in both kinds of distance.