Music Cognition and Perception

Building Blocks of Music

The basic elements of any sound are loudness, pitch, duration, timbre, spatial location, and reverberation. These dimensions are separable in that each can be varied without altering the others, allowing the scientific study of one at a time. Of [Page 600]the six, pitch and loudness are psychological constructions that map loosely (and perhaps nonlin-early) to the physical dimensions of frequency and amplitude.

When more than one tone is present, the sequence of pitches defines a musical interval, and intervals define contour—the direction of movement in a sequence of tones (up, down, or the same) without regard to the size of the intervals. Contour may be subject to preferential processing—infants attend to it more readily than they do intervals, and contour is more easily remembered by adults learning a new melody than the precise intervals.

The sequence of durations in a set of tones gives rise to rhythm, tempo (the pace or speed of the piece, loosely related to the temporal interval at which one would tap a foot or snap fingers), and meter (the way in which tones are perceived to be temporally grouped or organized, the most common in Western music being groups of two, three, or four). Our brains organize these fundamental perceptual attributes into higher level concepts—just as a painter arranges lines into shapes, contours, and forms. In music, these higher level concepts include melody and harmony. When we listen to music, we actually perceive multiple attributes or “dimensions” interacting.

Melodies are defined by the pattern or relation of successive pitches across time; most people have little trouble recognizing a melody that has been transposed in pitch. In fact, many melodies do not have a “correct” pitch, they just float freely in pitch space, starting anywhere one wants them to. “Happy Birthday” is an example of this, typically sung with naïve disregard to whether it is being sung in the same key from one occasion to another.

One way to think about a melody is that it is an abstract prototype, derived from specific instantiations of key, tempo, instrumentation, and so on. A melody is an auditory object that maintains its identity under certain transformations, just as a chair maintains its identity under certain transformations, such as moving it to the other side of the room, turning it upside down, or painting it red. (It was this property of melodies—the fact that their identity is defined in relational rather than absolute terms—that influenced the formation of the Gestalt psychology movement more than a hundred years ago by von Ehrenfels, Wertheimer, Koffka, and Köhler.) So for example, if you hear a song played louder than you're accustomed to, you can still identify it. If you hear it at a different tempo, played by a different instrument, or coming from a different location in space, it is still the same melody. Of course, extreme changes in any of these dimensions will render it unrecognizable; pitches outside the range of human hearing, a tempo of one beat per hour, or a loudness of 200 A-weighted decibels, dB(A), might stretch the limits of identification.

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