Functional differences between tonotopic and periodic information in recognition of transposed melodies: How do local cues affect global features?

Abstract

To recognize a transposed melody, two properties can be hypothesized to function as a significant invariant feature: a melodic contour, an up-down movement; and melodic intervals, the distances between consecutive pitches. Both properties are realized by changing the frequency of notes. Frequency changes are coded in two different ways in the early stages of the auditory process: tonotopicity and periodicity. In the first experiment, to investigate how differently transposed melodies are recognized depending on the two types of cue, two stimulus types were used: band noise (BN) providing mainly the tonotopic cue, and rippled noise (RN) providing the periodic cue. The results indicated that the contour invariance could be extracted from both cues. It was also indicated that the interval size information was contaminated in the contour information. A second experiment tested functional differences between the BN and RN stimuli in providing tonal contexts. The results showed that only the RN stimulus produced a "tonality" effect, which was reflected by an acute sense of "equality." The results verify that the periodic cue provides more accurate information for the melodic interval recognition than the tonotopic cue. The current study reaffirmed that local cues individually affected global features, that is, melodic contour and tonality. ©2008 The Acoustical Society of Japan.