Perception of structure in auditory patterns

Abstract

The present research utilised five tasks to investigate non-musicians' perception of phrase, rhythm, pitch and beat structure in unaccompanied Gaelic melodies and musical sequences.

Perception of phrase structure was examined using: i) a segmentation task in which listeners segmented Gaelic melodies into a series of meaningful units and ii) a novel click localisation task whereby listeners indicated where they perceived a superimposed click in the melody had occurred. Listeners consistently segmented the melodies into units of 2.4 - 5.4 seconds. Clicks which were positioned before and after perceived boundaries (identified by segmentation) were perceptually migrated towards the boundary. These results suggest that listeners perceptually differentiate between phrasal groups in melodies (See Sloboda & Gregory, 1980; Stoffer, 1985, for similar results with musicians).

Short term memory for rhythmic structure was examined using rhythm recall of computer generated sequences and Gaelic melodies. Computer generated rhythms with small tonal pitch intervals (1 - 4 semitones) were easier to recall than large atonal intervals (predominantly greater than 4 semitones). Recall of Gaelic melodies, containing repetitive rhythmic units, was better than recall of computer sequences. Pitch reversal of Gaelic melodies did not effect recall.

Beat-tapping with three Gaelic melodies revealed that the majority of listeners established the underlying beat 1.5 - 3 seconds (5 - 6 notes) after the start of the melodies.

Perception of meaning and content in two note melodic intervals and three Gaelic melodies was examined using an adjective pair two-alternative forced choice task. Responses to musical intervals showed evidence of perceptual similarity based mainly on interval size. Perceived information content in the melodies increased significantly by the fourth note.

The results suggest that the amounts of Gaelic melody which are: i) required to establish an underlying beat, ii) remembered after one hearing, and iii) perceptually grouped into a meaningful unit, include the unit of melody which is necessary to establish a basic meaning.