Browsing by Author "Allen, Emily"

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    Interactions of Pitch and Timbre: How Changes in One Dimension Affect Perception of the Other
    (2011-04-13) Allen, Emily
    In music, timbre differences allow us to distinguish between instruments, while pitch carries melody and harmony. In speech, timbre allows us to distinguish between speech sounds, while pitch carries important prosodic information. Pitch and timbre are two of the most fundamental attributes of auditory perception, yet the perceptual interactions of pitch and timbre are not well understood. The primary hypothesis for this experiment is that timbre and pitch, despite often being treated as separable dimensions, are not perceptually independent. The secondary hypothesis is that non-musicians and musicians will show perceptual differences on pitch and timbre discrimination tasks.
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    Perception and Processing of Pitch and Timbre in Human Cortex
    (2018-04) Allen, Emily
    Pitch and timbre are integral components of auditory perception, yet our understanding of how they interact with one another and how they are processed cortically is enigmatic. Through a series of behavioral studies, neuroimaging, and computational modeling, we investigated these attributes. First, we looked at how variations in one dimension affect our perception of the other. Next, we explored how pitch and timbre are processed in the human cortex, in both a passive listening context and in the presence of attention, using univariate and multivariate analyses. Lastly, we used encoding models to predict cortical responses to timbre using natural orchestral sounds. We found that pitch and timbre interact with each other perceptually, and that musicians and non-musicians are similarly affected by these interactions. Our fMRI studies revealed that, in both passive and active listening conditions, pitch and timbre are processed in largely overlapping regions. However, their patterns of activation are separable, suggesting their underlying circuitry within these regions is unique. Finally, we found that a five-feature, subjectively derived encoding model could predict a significant portion of the variance in the cortical responses to timbre, suggesting our processing of timbral dimensions may align with our perceptual categorizations of them. Taken together, these findings help clarify aspects of both our perception and processing of pitch and timbre.