Repetition Enhances the Musicality of Speech and Tone Stimuli to Similar Degrees

Abstract

Certain spoken phrases, when removed from context and repeated, begin to sound as if they were sung. Prior work has uncovered several acoustic factors that determine whether a phrase sounds sung after repetition. However, the reason why repetition is necessary for song to be perceived in speech is unclear. One possibility is that by default pitch is not a salient attribute of speech in non-tonal languages, as spectral information is more vital for determining meaning. However, repetition may satiate lexical processing, increasing pitch salience. A second possibility is that it takes time to establish the precise pitch perception necessary for assigning each syllable a musical scale degree. Here we tested these hypotheses by asking participants to rate the musicality of spoken phrases and complex tones with matching pitch contours after each of eight repetitions. Although musicality ratings were overall higher for the tone stimuli, both the speech and complex tone stimuli increased in musicality to a similar degree with repetition. Thus, although the rapid spectral variation of speech may inhibit pitch salience, this inhibition does not decrease with repetition. Instead, repetition may be necessary for the perception of song in speech because the perception of exact pitch intervals takes time.