SPEECH VERSUS NONSPEECH IN PITCH MEMORY

The memory trace of the pitch sensation induced by a standard tone (S) can be strongly degraded by subsequently intervening sounds (I). Deut sch [Science 168, 1604-1605 (1970)] suggested that the degradation is much weaker when the I sounds are words than when they are tones. In D eutsch's study, however, the pitch relations between S and the I words were not controlled. The first experiment reported here was similar t o that of Deutsch except that the speech and nonspeech stimuli used as I sounds were matched in pitch. The speech stimuli were monosyllabic words derived from recordings of a real voice, whereas the nonspeech s timuli were harmonic complex tones with a flat spectral profile. These two kinds of I sounds were presented at a variable pitch distance (De lta-pitch) from the S tone. In a same/different paradigm, S had to be compared with a tone presented 6 s later; this comparison tone could b e either identical to S or shifted in pitch by +/-75 cents. The nature of the I sounds (spoken words versus tones) affected discrimination p erformance, but markedly less than did Delta-pitch. Performance was be tter when Delta-pitch was large than when it was small, for the speech as well as nonspeech I sounds. In a second experiment, the S sounds a nd comparison sounds were spoken words instead of tones. The differenc es to be detected were restricted to shifts in fundamental frequency ( and thus pitch), the other acoustic attributes of the words being left unchanged. Again, discrimination performance was positively related t o Delta-pitch. This time, the nature of the I sounds (words versus ton es) had no significant effect. Overall, the results suggest that, in a uditory short-term memory, the pitch of speech sounds is not stored di fferently from the pitch of nonspeech sounds. (C) 1996 Acoustical Soci ety of America.