Development

Pitch

Without ever taking a music lesson, a typical adult listener can usually remember and accurately reproduce a repertoire of melodies, detect wrong notes, use context to form expectations about which pitches are most likely to occur, and respond meaningfully to emotion conveyed in a musical passage. Knowing the rules that govern musical pitch structure in one's culture may play a critical role in forging social bonds between members of a group, whether those ties are between lovers, friends, or caregivers and their young children.

Early abilities. A listener's earliest exposure to pitch information occurs in utero. During the third trimester of pregnancy, a fetus can hear its mother's voice, the voices of others, music, and other environmental sounds. Even though sound is attenuated in the high-frequency range (500+ hertz, or Hz) by the mother's abdomen, the prosodic contour of language and music is heard and discriminated by fetuses in the third trimester. [Page 331]Newborns prefer listening to the sounds they heard in utero, such as their native language or familiar melodies. In the months after birth, infants can detect changes in pitch as small as a third of a semitone, even though their detection and discrimination thresholds are elevated relative to adults until childhood.

Very early in life, infants are sensitive to musical and linguistic pitch contour, the pattern of rising and falling pitch in a sequence. Young infants prefer infant-directed (ID) to adult-directed (AD) speech and song, in large part because of the exaggerated melodic contours and music-like features of ID speech. Young infants respond in emotionally appropriate ways to ID speech contours (i.e., rising and bell-shaped contours attract and maintain attention, while falling contours soothe), and they respond differentially to different types of ID song, such as the low-pitched, slow-tempo lullabies versus higher-pitched, faster play songs. The ability to categorize melodies based on contour emerges by 5 to 8 months. For example, in a conditioned head-turn paradigm where infants are reinforced for turning their heads when they hear a novel stimulus, infants make head turns in response to a novel-contour melody but they ignore (or treat as same) transpositions or same-contour variations of the standard melody. Thus, melodic contour appears to be a defining feature of pitch for the youngest, least experienced listeners.

Infants are also sensitive to the consonance and dissonance of tone combinations. As early as a few days after birth, infants exhibit listening preferences for consonant over dissonant stimuli (such as two-tone intervals or musical passages). Likewise, 6-month-olds exhibit superior detection in the context of consonant than dissonant pitch patterns. These early biases are somewhat surprising given that definitions of consonance and dissonance are not universal but vary across cultures and/or historical periods. One possibility is that the auditory system of young infants is sensitive to low-level fluctuations in amplitude, or “beating,” and infants find this aversive. However, recent work suggests that adults' subjective ratings of pleasantness are uncorrelated with beating. Instead, pleasantness ratings are correlated with harmonicity (the extent to which the acoustic spectrum of a sound conforms to a single harmonic series), and harmonicity ratings correlate with experience (i.e., years of music training). This implies that a preference for consonance may increase over the course of development with experience.

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