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DOI: 10.1177/1084713806292648 New Perspectives on Assessing Amplification EffectsDepartment of Speech and Hearing Sciences, University of Washington, Seattle, Washington, psouza{at}u.washington.edu
Department of Speech and Hearing Sciences, University of Washington, Seattle, Washington Clinicians have long been aware of the range of performance variability with hearing aids. Despite improvements in technology, there remain many instances of well-selected and appropriately fitted hearing aids whereby the user reports minimal improvement in speech understanding. This review presents a multistage framework for understanding how a hearing aid affects performance. Six stages are considered: (1) acoustic content of the signal, (2) modification of the signal by the hearing aid, (3) interaction between sound at the output of the hearing aid and the listeners ear, (4) integrity of the auditory system, (5) coding of available acoustic cues by the listeners auditory system, and (6) correct identification of the speech sound. Within this framework, this review describes methodology and research on 2 new assessment techniques: acoustic analysis of speech measured at the output of the hearing aid and auditory evoked potentials recorded while the listener wears hearing aids. Acoustic analysis topics include the relationship between conventional probe microphone tests and probe microphone measurements using speech, appropriate procedures for such tests, and assessment of signal-processing effects on speech acoustics and recognition. Auditory evoked potential topics include an overview of physiologic measures of speech processing and the effect of hearing loss and hearing aids on cortical auditory evoked potential measurements in response to speech. Finally, the clinical utility of these procedures is discussed.
Key Words: evoked potentials hearing aids speech hearing loss probe microphone
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