Vickers, DA;
Moore, BCJ;
Williges, B;
Boyle, P;
Salorio-Corbetto, M;
Schlittenlacher, J;
Haywood, NR;
(2023)
Using Measures of Amplitude Modulation Processing to Understand Function of Electrically Stimulated Auditory Pathways.
In:
Proceedings of Forum Acusticum.
European Acoustics Association Forum Acusticum: Torino, Italy.
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Abstract
For cochlear implant (CI) listeners, speech information transmission is reliant upon the ability to process the amplitude-modulated (AM) envelope of speech sounds independently in different channels. This can be hindered for many reasons, not least due to spread of electrical current or neural degeneration. We employed a psychoacoustic task to explore AM processing. We recruited normal-hearing adults and adult CI listeners (Nucleus and Advanced Bionics). Acoustic sinusoids of two different rates (for example, 13 versus 40 Hz) were discriminated in a three-interval two-alternative forced choice task, where the modulation depth was adjusted adaptively to derive an AM discrimination threshold. Testing was conducted with and without speech envelope interferers on neighbouring channels. Stimuli were delivered through headphones (HD600s). All front-end noise reduction features were de-activated. We explored AM processing across the frequency range. Initial findings suggest that AM discrimination was poorer in the presence of interferers. There is variability across CI listeners and within the dataset of individual listeners. We interpret the measure as an indicator of neural function when interferers are absent and indicative of channel interaction when interferers are present. We will calculate the normative ranges for the measures. problems of neural survival and channel interaction. Ongoing work will compare findings to objective measures of viability of the electrode-neurone interface and speech in noise measures.
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