The effects of F0 manipulation on the perceived distance of speech

Recent research has shown that the apparent distance of speech increases systematically with the vocal effort level of the talker. At this point, however, it is not clear how the different acoustic features of speech that change with vocal effort contribute to this increase in apparent distance. In this experiment, pitch-synchronous overlap and add (PSOLA) techniques were used to modify the F0 contours of prerecorded speech signals to match the F0 contours of speech samples that were produced at 6 dB higher output levels and at 6 dB lower output levels. The other characteristics of the speech signals were left unchanged. Psychoacoustic tests of the resulting speech signals show that the synthetic F0 shifts could account for some, but not all, of the apparent changes in distance that occur with a 6 dB change in the output level of the talker.