Infants tune in to the sounds of music.

Infants tune in to the sounds of music

The next time you go to a concert or crank up your stereo, consider this: Unconscious tendencies to perceive some types of music as more melodic and "in tune" than others may have taken root before your first birthday.

Just as previous research indicates that infants are born with the ability to perceive speech sounds from any language in the world, new data suggest that 6-month-olds innately perceive the structure of musical scales from a variety of cultures, report psychologist Micahel P. Lynch of the University of Miami and his co-workers in the July PSYCHOLOGICAL SCIENCE.

By age 1, however, exposure to the music of one's own culture begins to shape musical perception, Lynch asserts. "People rapidly develop an unconscious cultural knowledge of what to expect when they hear music -- what sounds reasonable and what sounds weird," he says.

Lynch and his colleagues composed computer-generated, seven-note melodies based on Western major and minor scales and the Javanese pelog scale. Each musical note corresponds to a certain number of sound waves per second, known as its frequency. Musical notes sound higher as their frequency climbs. In melodies based on Western scales, specific acoustic intervals between notes, called frequency ratios, regularly occur. May Western scales exist, but popular and classical music rely predominantly on the major and minor scales. Javanese music often sounds strange to Western ears because it features different, more complex frequency ratios.

The Miami scientists studied 20 6-month-olds, 10 musically inexperienced adults, 10 amateur musicians and 10 professional musicians, all of whom live in the United States. Participants were tested in distinguishing a well-tuned version of a major, minor or pelog melody from one in which the fifth note was mistuned by raising its frequency. Adults first heard the well-tuned melody played continuously, with the fifth note periodically raised and played louder than the other notes. They then heard random presentations of well-tuned and mistuned melodies and raised their hands when they thought a mistuned version occurred.

Before testing, 6-month-olds were trained to notice a frequency increase of the fifth note in either the pelog or major melody. They identified fifth-note changes by turning their heads toward a loudspeaker, where an animated toy was activated after a correct response. The infants then heard both renditions of all three melodies and turned their heads to indicate mistuned versions.

Six-month-olds correctly classified melodies based on all three scales two-thirds of the time, regardless of whether they first heard the pelog or major tunes. But adults performed better overall on the two native Western scales, correctly classifying nearly three-quarters of them versus two-thirds of the pelog presentations. Professional musicians correctly noted pelog mistunings almost as often as major and minor deviations. "Experienced musicians may develop special abilities to deal with novel musical information," Lynch says.

In an unpublished study, his team has found that 1-year-olds often recognize mistuned melodies based on the major scale but are less successful with melodies derived from either the pelog or the Western augmented scale. The latter scale is rarely used except by a few jazz musicians. Between 6 months and 1 year of age, infants regularly exposed to specific musical scales apparently begin to perceive them as more "music-like" than other scales, Lynch maintains.

On the other hand, the success of 6-month-olds in perceiving pelog scales challenges the assumption of many music theorists that Western scales are inherently easier for the brain to process because they rely on mathematically simpler relationships between the frequencies of musical notes.