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Discrimination of gain increments in speech-shaped noises

Caswell-Midwinter, Benjamin; Whitmer, William

Discrimination of gain increments in speech-shaped noises Thumbnail


Benjamin Caswell-Midwinter


Frequency-dependent gain adjustments are routine in hearing-aid fittings, whether in matching to real-ear targets or fine-tuning to patient feedback. Patient feedback may be unreliable and fittings inefficient if adjustments are not discriminable. To examine what gain adjustments are discriminable, we measured the just-noticeable differences (JNDs) for increments in speech-shaped noises processed with prescription gains. JNDs were measured in the better ears of 38 participants with hearing impairment using a fixed-level, same-different task. JNDs were measured for increments at six individual frequency-bands: a 0.25 kHz low-pass band, octave-wide bands at 0.5, 1, 2 and 4 kHz, and a 6 kHz high-pass band. JNDs for broadband increments were also measured. JNDs were estimated at d’ of 1 for a minimally discriminable increment in optimal laboratory conditions. The JND for frequency-band increments was 2.8 dB excluding the 0.25 kHz low-pass band, for which the JND was 4.5 dB. The JND for broadband increments was 1.5 dB. Participants’ median frequency-band and broadband JNDs were positively correlated. JNDs were mostly independent of age, pure-tone thresholds and cognitive score. In consideration of self-fitting adjustments in noisier conditions, JNDs were additionally estimated at a more sensitive d’ of 2. These JNDs were 6 dB for bands below 1 kHz, and 5 dB for bands at and above 1 kHz. Overall, the results suggest noticeable fine-tuning adjustments of 3 dB and self-fitting adjustments of 5 dB.

Journal Article Type Article
Acceptance Date Nov 19, 2018
Online Publication Date Jan 18, 2019
Publication Date Jan 18, 2019
Deposit Date Nov 21, 2018
Publicly Available Date Jan 25, 2019
Journal Trends in Hearing
Electronic ISSN 2331-2165
Publisher SAGE Publications
Peer Reviewed Peer Reviewed
Volume 23
Pages 1-12
Public URL
Publisher URL


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