Identification of temporal order in three-tone sequences

Well-trained subjects identified with remarkable accuracy the temporal order of three contiguous pure tones of different frequencies, presented as a single sequence. For a given set of three frequencies covering a one-octave span, the minimum duration of each component tone necessary for absolute identification of a sequence was 2–7 msec on the average. A total frequency range narrower than 1/3–2/3 octave depressed the identifiability of temporal order, whereas increasing the frequency range beyond this limit had no appreciable effect. Simple harmonic relation between the three components was associated with higher identification performace than was a complex harmonic relation. In general, those temporal orders in which the frequency change was unidirectional were more easily identified than the others. Also, the highest and the lowest of the three tones in final position were recognized more often than any of the sequences and were, most probably, used by the observers as cues for the identification of sequences.