The influence of aided speech in noise performance on hearing aid setting preference in hearing impaired listeners
The fitting of a new hearing instrument (HI) will almost invariably take place in a speech in quiet (SiQ) situation. An acoustician and the hearing impaired patient may engage in a short conversation as to the patient's preferred HI settings. This may result in an individual adjustment of gain/compression and adaptive HI features for this patient. Unsurprisingly, it is quite common for the hearing impaired patient to come back and report difficulties in real-life speech in noise (SiN) situations. At the first glance, performing a SiN test with different HI settings might help the acoustician achieve a more accurate HI fitting. But is this really so? Firstly, such a procedure would be extremely time and effort demanding. Secondly, it is unclear whether current standard SiN tests sufficiently reflect the difficulties of a real-life SiN situation. Lastly, there remains the question of whether the hearing impaired person would accept the HI settings that resulted in his/her best SiN performance. In the study reported here we investigated the influence of SiN performance with specific HI settings on the preference for these settings.
30 impaired subjects were tested with four HI settings in terms of their SiN and SiQ performance as well as regarding their overall spontaneous acceptance of the settings. The SiN test was a selective, real-speech listening task requiring an auditory number comparison rendered more difficult by a distracting talker and an eight- speaker free field cafeteria-noise environment, the so called Numbers in Babble (NiB) test. The SiQ test was the standard monosyllabic word test whereas the spontaneous acceptance was calculated as the sum of subjective evaluations of various sound attributes pertinent to SiN, SiQ, environmental noise, music and own voice sound examples. Subjective and objective listening effort were also measured during the NiB task. We found no significant correlation between the performance in NiB task for a given HI setting and subject’s preference for that setting according to the spontaneous acceptance. In other words, subject's ability to perform well in SiN task, with a specific HI setting, was not reflected in his/hers preferences for this setting. Equally, there was no correlation between the listening effort involved in the SiN task and the subjective preferences, for the given setting. One simple interpretation of this finding is that subjectively preferred HI setting is chosen on the basis of sound dimensions other than that of SiN understanding. Implications of these results will be discussed.