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Abstract
We evaluated the benefits of fast-acting WDRC, slow-acting AVC, and linear reference fittings for speech intelligibility and reported disability, in a within-subject within-device masked crossover design on 50 listeners with SNHL. Five hearing aid fittings were implemented having two compression channels and seven frequency bands. Each listener sequentially experienced each fitting for a 10-week period. Outcome measures included speech intelligibility under diverse conditions and self-reported disability. At a group level, each nonlinear fitting was superior to the linear references for benefits in listening comfort, listener satisfaction, reported intelligibility and speech intelligibility. Slow-acting AVC outperformed the fast-acting WDRC fittings for listening comfort, while for reported and measured speech intelligibility the converse was true. For listener satisfaction there were no group differences between the nonlinear fittings. Analysis in terms of fittings for individual listeners revealed subsets with definite divergences from the group data and hence a need for candidature criteria. There are systematic differences between the benefits of nonlinear and linear fittings, and also within nonlinear fittings with fast versus slow time constants. The patterns of benefit and individual optima depend on the domain of outcome being assessed.
Sumario
Evaluamos en cincuenta sujetos con SNHL los beneficios sobre la inteligibilidad del lenguaje de adaptaciones de auxiliares auditivos con WDRC de acción rápida, con AVC de acción lenta y con referencia lineal, así como la discapacidad reportada, con un diseño de enmascaramiento cruzado que permite juzgar las diferencias intra-sujeto y en función del propio dispositivo. Se implementaron cinco adaptaciones con dos canales de compresión y siete bandas de frecuencia. Cada sujeto utilizó secuencialmente las diferentes adaptaciones durante un período de diez semanas. Las medidas de resultado incluyeron inteligibilidad del lenguaje bajo diversas condiciones y la discapacidad auto-reportada. La adaptación con AVC de acción lenta superó la de WDRC de acción rápida en relación con la comodidad para escuchar, aunque para la inteligibilidad del lenguaje, tanto medida como reportada, ocurrió lo contrario. En relación con la satisfacción del sujeto, no existieron diferencias de grupo entre las adaptaciones no lineales. El análisis, en términos en adaptaciones para sujetos individuales, reveló sub-grupos con divergencias definitivas en relación a los datos grupales, y por tanto, la necesidad de establecer criterios para la selección de candidatos. Existen diferencias sistemáticas entre los beneficios de las adaptaciones lineales y no lineales, así como entre las adaptaciones no lineales y las constantes temporales rápidas versus las lentas. El patrón de beneficio y de optimización individual depende del ámbito de resultado bajo escrutinio.
| Acronyms | ||
| AVC | = | automatic volume control |
| HTL | = | hearing threshold level |
| IG | = | insertion gain |
| SNHL | = | sensorineural hearing loss |
| ULL | = | uncomfortable listening level |
| WDRC | = | wide dynamic range compression |
| Acronyms | ||
| AVC | = | automatic volume control |
| HTL | = | hearing threshold level |
| IG | = | insertion gain |
| SNHL | = | sensorineural hearing loss |
| ULL | = | uncomfortable listening level |
| WDRC | = | wide dynamic range compression |
Notes
Throughout this manuscript we use the term ‘benefit factor’ to describe the advantages that might accrue following successful hearing aid fitting. Within that general construct, advantages might accrue in terms of overall listener satisfaction, listening comfort and perceived intelligibility. We do not use the terms ‘benefit’ and ‘satisfaction’ as referring to fundamentally dissociated domains.