Perception of vocal effort and distance from the speaker on the basis of vowel utterances.

The sound pressure level of vowels reflects several nonlinguistic and linguistic factors: distance from the speaker, vocal effort, and vowel quality. Increased vocal effort also involves the 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, and that they compensate for most of the between-vowel variation in level. The results obtained when listeners had to estimate vocal effort as well as distance suggest that an analysis of an utterance takes place at an early stage in auditory processing, before memories of episodes are stored.