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Date of Graduation
Bachelor of Science (BS)
Department of Communication Sciences and Disorders
Recent psychoacoustic experiments (Böckmann-Barthel et al., 2014; Deike et al., 2012) have re-examined research regarding stream segregation and the build-up effect. Stream segregation is the ability to discern auditory objects within a stream of information, such as distinguishing one voice amongst background noise or an instrument within an orchestra. Initial works examining this topic proposed that auditory information is not immediately distinguished as various streams, but rather that differences accumulate over time, allowing listeners to segregate information following a period of build-up (i.e., the build-up effect); whereas more current findings indicate a build-up period is unnecessary for segregation. This experiment’s methods were based on those of older studies of stream segregation and the build-up effect, but aimed to gather first perceptual responses to stimuli within a window of time more realistic than prior studies, in which subjects seemed to hesitate before giving their first responses of their stream perception. The main differences explored were prompting and training of subjects, allowing subjects to become familiar with stimuli prior to data gathering, and re-instructing subjects if their response times seemed to indicate they still did not understand the task. Another goal of this experiment was to gather data to further assess current beliefs of an inability of cochlear implant-wearing (CI) listeners to harness auditory cues in streaming of information, due to degraded information relative to that of normal-hearing (NH) listeners (Cooper & Roberts, 2009).
Normal-hearing and cochlear implant listeners in this experiment indicated whether they experienced one or two auditory streams during a 24.7 second window of stimuli presentation consisting of alternating A and B noise bursts. This experiment examined correlations between spectral difference, amplitude-modulation rate, and initial response of stream number perception. Results from this experiment indicated that spectral cues are often salient enough to result in high probabilities of a segregated or integrated perception in NH listeners, though not in CI listeners. These findings are congruent with prior research. Findings also indicate that in conditions without spectral separation, AM-rate differences greater than two-octaves generate a build-up of segregated perception in NH listeners. Overall, while observations of CI listeners thus far suggest possible build-up segregation elicited by robust spectral cues, no data indicate that AM-rate cues are being harnessed to aid in streaming.
Wheeler, Harley J., "Build-up effect of auditory stream segregation using amplitude-modulated narrowband noise" (2016). Senior Honors Projects, 2010-2019. 216.