In the past decade, there has been a preoccupation with the relationship between speech and music in psychological literature. This research aims to determine if language acquisition and speech perception correlate to music perception. Previous research proposed that whether an auditory stimulus is perceived as music or speech is assumed to be a result of its acoustic properties. Thus many studies focused on decoding, or reverse-engineering, the acoustic components of speech and music. However, recent research has proposed that music and speech might be processed differently on a neural level, suggesting that it is not necessarily the acoustic properties of auditory stimulus that result in the perception of music or speech, but rather independent neural correlates. To illustrate this theory, Diana Deutsch, Trevor Henthom, and Rachael Lapidis, examined an auditory illusion, one in which a repeated segment of speech was transformed to sound musical.
Fifty-four subjects who had at least five years of music training were recruited and divided into three groups. The experiment was split into two sections. During all conditions a recording of Deutsch speaking the text, “the sounds as they appear to you are not only different from those that are really present, but they sometimes behave so strangely as to seem quite impossible,” was presented to the subjects. Then the excerpt “sometimes behave so strangely” was repeated 10 times. In the first condition, this excerpt was left unchanged. But in the second and third conditions the excerpt was transposed and jumbled (respectively).
In the first section, the participants listened to this phrase and judged on a scale from 1 to 5 if it sounded “exactly like speech” or “exactly like singing.” In the second section, the same paradigm was used except the subjects were instructed to repeat the phrase back to the experimenter.
The results showed that as the excerpt was repeated, participants started to perceive the speech as singing. Interestingly, in the second section, the participants even sung back the phrase. Deutsch and al. theorize this might be a result of variable pitch salience – in speech, the pitch contour of a phrase often goes unnoticed. However, the participants reported that when the phrase was repeated the pitch properties became more dominant. The researchers believe that such repetition might disarm certain neural circuitry that inhibits our perception of pitch in normal speech.
Deutsch, D., Henthom, T., & Lapidis, R. (2011). Illusory transformation from speech to song. Acoustical Society of America, 2245-2252.