Comparison of an 'intuitive' NHS hearing aid prescription method with DSL 4.1 targets for amplification

This study aimed to evaluate current practice in a National Health Service Trust in setting hearing aid output to meet amplification targets prescribed by desired sensation level (DSL) using a range of NHS hearing aids. A consecutive sample of 33 patients was drawn from the hearing aid waiting list of the Royal Devon & Exeter Hospital (RD&E). The age range was 33-83 years. Patients not giving written consent and those with complex hearing losses were excluded. At review, pure-tone audiogram, uncomfortable loudness levels, real-ear coupler difference, user gain and maximum output were recorded. Data were entered into DSL 4.1 prescription software. Wilcoxon tests were used to compare the measured user gain and maximum output with DSL 4.1-generated targets. The results demonstrate significant differences (p<0.05) at 0.25, 0.5, 0.75, 1.5, 2, 3, 4 and 6 kHz between target and measured values for user gain. This study reveals that the routine intuitive method for prescribing hearing aids at the RD&E is not effective in meeting targets for amplified speech as prescribed by DSL.