Discrimination of gain increments in speech-shaped noises

Caswell-Midwinter, B. and Whitmer, W. M. (2019) Discrimination of gain increments in speech-shaped noises. Trends in Hearing, 23, pp. 1-12. (doi: 10.1177/2331216518820220) (PMID:30803400) (PMCID:PMC6351966)

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.

• Item Type: Articles
• Additional Information: This work was supported by funding from the Medical Research Council (grant numbers MR/S003576/1, U135097131 and 1601056) and the Chief Scientist Office of the Scottish Government
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Whitmer, Dr William and Caswell-Midwinter, Benjamin
• Authors: Caswell-Midwinter, B., and Whitmer, W. M.
• Subjects: B Philosophy. Psychology. Religion > BF Psychology; R Medicine > RF Otorhinolaryngology
• College/School: College of Medical Veterinary and Life Sciences
• Journal Name: Trends in Hearing
• Publisher: SAGE Publications
• ISSN: 2331-2165
• ISSN (Online): 2331-2165
• Published Online: 18 January 2019
• Copyright Holders: Copyright © 2019 The Authors
• First Published: First published in Trends in Hearing 23: 1-12
• Publisher Policy: Reproduced under a Creative Commons License