Binaural integration of melodic patterns.

Training Grant MH-21001. I am especially indebted to R. Erickson for valuable discussions concerning channeling principles in music. Requests for reprints should be sent to Diana Deutsch, Department of Psychology, C-009, University of California at San Diego, La Jolla, California 92093 It has been argued on a number of grounds that we have difficulty in integrating rapid streams of acoustic information when these are presented separately to the two ears. For instance, Cherry and Taylor (1954) studied the intelligibility of speech which was switched alternately between the ears, and found a substantial drop in intelligibility at alternation rates of around 3 cps. They interpreted their results in terms of a limitation in the rate at which we can switch our attention from ear to ear. This explanation was, however, challenged by Huggins (1964), who found that the maximum dip in intelligibility shifted in parallel with a shift in the speech rate. He therefore argued that this effect was due to interference in the processing of basic units of speech, rather than to a limitation in attention switching time. A second line of evidence involves the recall of lists of dichotically presented digits. Broadbent (1954, 1958) found that when two lists of digits are simultaneously presented at fast rates, one to each ear, subjects recall these better by ear than by temporal order, which would require switching between ears. Treisman (1971) further found that subjects were less able to recall successive lists of digits when these were presented alternately to the two ears than when they were presented binaurally. These effects cannot be ascribed to a perceptual interference with basic units of speech, since the integrity of the verbal items was preserved in these experiments. A further argument was advanced by Axelrod, Guzy, and Diamond (1968). They required subjects to compare the repetition rates of clicks which were presented either monotically or alternating dichotically, and found that the dichotic rates were consistently