Discrimination of gain increments in speech-shaped noises

Caswell-Midwinter, Benjamin; Whitmer, William

Abstract

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.

Citation

Caswell-Midwinter, B., & Whitmer, W. (2019). Discrimination of gain increments in speech-shaped noises. Trends in Hearing, 23, 1-12. https://doi.org/10.1177/2331216518820220

• 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
• DOI: https://doi.org/10.1177/2331216518820220
• Public URL: https://nottingham-repository.worktribe.com/output/1294861
• Publisher URL: https://journals.sagepub.com/doi/full/10.1177/2331216518820220
• Contract Date: Jan 25, 2019