Psychophysical Sensitivity and Physiological Response to Amplitude Modulation in Adult Dyslexic Listeners This study reports two experiments conducted to assess the sensitivity of dyslexic listeners to amplitude modulation (AM) of acoustic stimuli. The smallest detectable depth of AM of white noise was measured as a function of modulation frequency. Dyslexic listeners had significantly higher thresholds of AM depth than did matched control ... Article/Report
Article/Report  |   August 1999
Psychophysical Sensitivity and Physiological Response to Amplitude Modulation in Adult Dyslexic Listeners
 
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Language Disorders / Reading & Writing Disorders / Hearing
Article/Report   |   August 1999
Psychophysical Sensitivity and Physiological Response to Amplitude Modulation in Adult Dyslexic Listeners
Journal of Speech, Language, and Hearing Research, August 1999, Vol. 42, 797-803. doi:10.1044/jslhr.4204.797
History: Received March 26, 1998 , Accepted February 8, 1999
 
Journal of Speech, Language, and Hearing Research, August 1999, Vol. 42, 797-803. doi:10.1044/jslhr.4204.797
History: Received March 26, 1998; Accepted February 8, 1999

This study reports two experiments conducted to assess the sensitivity of dyslexic listeners to amplitude modulation (AM) of acoustic stimuli. The smallest detectable depth of AM of white noise was measured as a function of modulation frequency. Dyslexic listeners had significantly higher thresholds of AM depth than did matched control listeners. We also recorded the scalp potential evoked by AM of white noise (the amplitude modulation following response, AMFR). Dyslexic listeners had significantly smaller AMFRs than did matched control listeners. The reduced AMFR is consistent with reduced sensitivity to AM, and there was a strong association between these psychophysical and physiological measures. This deficit in AM sensitivity may result in impaired perception of the AM present in speech.

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