Browsing by Author "Graves, Jackson"
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Item Melodic Continuation in Three Dimensions(2012-04-18) Graves, JacksonOn hearing a sequence of pitches, listeners develop expectations for how that sequence will continue. Research on melodic continuation generally supposes two kinds of factors: the top-down influence of perceived tonality, and the bottom-up influence of melodic contour (relative size and direction of the intervals). For bottom-up, contour-based factors, there is converging evidence that melodies with good continuation tend to have small intervals between notes and narrow overall ranges. Since melodic contour can also be perceived in sequences of notes varying in brightness (an aspect of timbre or sound quality) or loudness instead of pitch, it is reasonable to suppose that the same contour-based expectations that apply to pitch sequences also apply to brightness and loudness sequences. The present study found that perceptive continuation ratings for brightness and loudness sequences generally conform to the same contour-based expectations as pitch sequences, though some differences between dimensions were found. This is compatible with the hypothesis that perception of melodic contour is a general auditory phenomenon that is not unique to pitch. The ratings for brightness and loudness sequences were more similar to each other than to ratings for pitch sequences, and it is likely that the factors that set pitch apart from other auditory dimensions are closely related to perceived tonality.Item Perception of multiple pitches: Sequential and simultaneous pitch relationships(2018-01) Graves, JacksonThe perception of pitch, a dimension of sound that is important for music perception, speech perception, and sound source segregation, is influenced by its context, both sequential and simultaneous. In music, pitch sequences form melodic contours, and simultaneous pitches form chords and harmony. A series of experiments investigated the perception of melodic contour in pitch as well as two other auditory dimensions, brightness and loudness. The results showed that subjective ratings of continuation for brightness and loudness sequences conformed to the same general contour-based expectations as pitch sequences, suggesting that melodic expectations are not unique to the dimension of pitch. Listeners with congenital amusia, however, exhibited less impairment on a short-term memory task for loudness contours than for pitch contours, suggesting a pitch-specific deficit. In a pair of experiments, priming of a familiar tonal context improved accuracy on a pitch interval discrimination task. However, the overall benefit to performance from tonal context was small, suggesting that previously reported effects of response time may mainly reflect expectancy as opposed to perceptual accuracy. In the last series of experiments, listeners accurately identified pitches in mixtures of three concurrent complex tones, despite poor peripheral resolvability. These stimuli help to dissociate two normally confounded variables in complex pitch, harmonic number and peripheral resolvability. The results were compared with outputs from two kinds of auditory models, one based on the rate-place code for pitch and the other based on the temporal code. Overall, these findings suggest that pitch perception involves bottom-up integration of both spectral and temporal information, as well as top-down effects of learning and context.