ORCID Profile
0000-0001-8297-2628
Current Organisation
University of Nottingham
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Publisher: Wiley
Date: 22-07-2008
DOI: 10.1002/HBM.20615
Publisher: American Physiological Society
Date: 06-2015
Abstract: The speech-evoked auditory brain stem response (speech ABR) is widely considered to provide an index of the quality of neural temporal encoding in the central auditory pathway. The aim of the present study was to evaluate the extent to which the speech ABR is shaped by spectral processing in the cochlea. High-pass noise masking was used to record speech ABRs from delimited octave-wide frequency bands between 0.5 and 8 kHz in normal-hearing young adults. The latency of the frequency-delimited responses decreased from the lowest to the highest frequency band by up to 3.6 ms. The observed frequency-latency function was compatible with model predictions based on wave V of the click ABR. The frequency-delimited speech ABR litude was largest in the 2- to 4-kHz frequency band and decreased toward both higher and lower frequency bands despite the predominance of low-frequency energy in the speech stimulus. We argue that the frequency dependence of speech ABR latency and litude results from the decrease in cochlear filter width with decreasing frequency. The results suggest that the litude and latency of the speech ABR may reflect interin idual differences in cochlear, as well as central, processing. The high-pass noise-masking technique provides a useful tool for differentiating between peripheral and central effects on the speech ABR. It can be used for further elucidating the neural basis of the perceptual speech deficits that have been associated with in idual differences in speech ABR characteristics.
Publisher: Acoustical Society of America (ASA)
Date: 04-2013
DOI: 10.1121/1.4793270
Abstract: At high frequencies, interaural time differences (ITDs) are conveyed by the sound envelope. Sensitivity to envelope ITDs depends crucially on the envelope shape. Reverberation degrades the envelope shape, reducing the modulation depth of the envelope and the slope of its flanks. Reverberation also reduces the envelope interaural coherence (i.e., the similarity of the envelopes at two ears). The current study investigates the extent to which these changes affect sensitivity to envelope ITDs. The first experiment measured ITD discrimination thresholds at low and high frequencies in a simulated room. The stimulus was either a low-frequency narrowband noise or the same noise transposed to a higher frequency. The results suggest that the effect of reverberation on ITD thresholds was multiplicative. Given that the threshold without reverberation was larger for the transposed than for the low-frequency stimulus, this meant that, in absolute terms, the thresholds for the transposed stimulus showed a much greater increase due to reverberation than those for the low-frequency stimulus. Three further experiments indicated that the effect of reverberation on the envelope ITD thresholds was due to the combined effect of the reduction in the envelope modulation depth and slopes, as well as the decrease in the envelope interaural coherence.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Katrin Krumbholz.