Browsing by Subject "Auditory stream segregation"
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Item Auditory stream segregation using cochlear implant simulations.(2010-06) Nie, YingjiuThis project studies auditory stream segregation as an underlying factor for poor speech perception skills in cochlear implant (CI) users by testing normal-hearing adults who listen to CI simulated sounds. Segregation ability was evaluated by behavioral responses to stimulus sequences consisting of two interleaved sets of noise bursts (A and B bursts). The two sets differed in physical attributes of the noise bursts including spectrum, or amplitude modulation (AM) rate, or both. The amount of the difference between the two sets of noise bursts was varied. Speech perception in noise was measured as the AM rate of the noise varied and at different spectral separations between noise and speech. Speech understanding and segregation ability are correlated statistically. Results show the following: 1. Stream segregation ability increased with greater spectral separation, with no segregation seen when A and B bursts had the same spectrum or when they involved the most overlapping spectra. 2. Larger AM-rate separations were associated with stronger segregation abilities in general. 3. When A and B bursts were different in both spectrum and AM rate, larger AM-rate separations were associated with stronger stream segregation only for the condition that A and B bursts were most overlapping in spectrum. 4. Speech perception in noise decreased as the spectral overlapping of speech and noise increased. 5. Nevertheless, speech perception was not different as the AM rate of the noise varied. 6. Speech perception in both steady-state and modulated noise was found to be correlated with stream segregation ability based on both spectral separation and AM-rate separation. The findings suggest that spectral separation is a primary/stronger cue for CI listeners to perform stream segregation. In addition, AM-rate separation could be a secondary/weaker cue to facilitate stream segregation. The spectral proximity of noise and speech has a strong effect on CI simulation listeners' speech perception in noise. Although neither the presence of noise modulation nor the modulation rate affected CI simulation listeners' speech understanding, the ability to use the AM-rate cue for segregation is correlated with their speech understanding. The results suggest that CI users could segregate different auditory streams if the spectral and modulation rate differences are large enough; and that their ability to use these cues for stream segregation may be a predictor of their speech perception in noise.Item Data supporting "Perceptually salient differences in a species recognition cue do not promote auditory streaming in eastern gray treefrogs (Hyla versicolor)"(2024-05-02) Kalra, Lata; Altman, Shoshana; Bee, Mark A; latakalra94@gmail.com; Kalra, LataThis dataset corresponds to behavioral choice tests performed on the females of Hyla versicolor to investigate if this species uses perceptually salient differences in species-recognition cue (pulse rise time) to segregate the signal of a potential mate from other overlapping sounds in the environment. Females in this species chose a potential mate based on the properties of the advertisement call. Advertisement calls having slow pulse rise times (time elapsed from the beginning of a pulse to the pulses's maximum amplitude) and slow pulse repetition rate (around 20 pulses/s) are behaviorally attractive to the females. In contrast, calls having fast rise times and fast pulse rates (~40-50 pulses/s) are unattractive. Here, we exploited the subjects' inherent attractiveness for slow rise times and slow pulse rates to design interleaved pulsatile sequences ABAB (repeating at an unattractive pulse rate of 40 pulses/s) having behaviorally attractive slow (pulses 'A'), and behaviorally unattractive fast (pulses 'B') rise-times. We hypothesized that if the rise-times differences between pulses 'A' and 'B' are perceptually salient then the subjects should segregate ABAB into two sequences (A-A- and B-B-, each at an attractive rate of 20 pulses/s each). We first tested (using a two-alternative choice test; Test C3) if the differences between the two rise times were perceptually salient (subjects got a choice between A-A- and B-B-). We then gave the subjects a segregation task (using a four-alternative choice test; Test T1) wherein they got a choice between four alternatives, three of which were designed to be unattractive (AAAA, BBBB and AABB). The fourth alternative ABAB was attractive only if the subjects could segregate A-A- and B-B-, so as to perceive the "attractive" slow pulse rise time at an "attractive" rate of 20 pulses/s. We did an additional test (using a four-alternative choice test; Test C1) to confirm that subjects prefer slow pulse rise times, slow pulse rates and regular pulse-timing patterns within the calls (a four-alternative choice between AAAA, BBBB, AA-- and A-A-). For each test, we recorded if the subject responded by making a choice ('yes' or 'no'), if it responded, which alternative did it chose, and how long did it take to make the choice (choice latency). We also recorded a subject's id, the temperature at which the behavioral test was performed, and the Sound Pressure Level (SPL) of the broadcast stimuli.