Rallapalli Varsha, Anderson Melinda, Kates James, Balmert Lauren, Sirow Lynn, Arehart Kathryn, Souza Pamela
Department of Communication Sciences & Disorders, Northwestern University, Evanston, Illinois, USA.
Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Ear Hear. 2020 Mar-Apr;41(2):433-441. doi: 10.1097/AUD.0000000000000767.
Hearing aids provide various signal processing techniques with a range of parameters to improve the listening experience for a hearing-impaired individual. In previous studies, we reported significant differences in signal modification for mild versus strong signal processing in commercially available hearing aids. In this study, the authors extend this work to clinically prescribed hearing aid fittings based on best-practice guidelines. The goals of this project are to determine the range of cumulative signal modification in clinically fit hearing aids across manufacturers and technology levels and the effects of listening conditions including signal to noise ratio (SNR) and presentation level on these signal modifications.
We identified a subset of hearing aids that were representative of a typical clinical setting. Deidentified hearing aid fitting data were obtained from three audiology clinics for adult hearing aid users with sensorineural hearing loss for a range of hearing sensitivities. Matching laboratory hearing aids were programmed with the deidentified fitting data. Output from these hearing aids was recorded at four SNRs and three presentation levels. The resulting signal modification was quantified using the cepstral correlation component of the Hearing Aid Speech Quality Index which measures the speech envelope changes in the context of a model of the listener's hearing loss. These metric values represent the hearing aid processed signal as it is heard by the hearing aid user. Audiometric information was used to determine the nature of any possible association with the distribution of signal modification in these clinically fit hearing aids.
In general, signal modification increased as SNR decreased and presentation level increased. Differences across manufacturers were significant such that the effect of presentation level varied differently at each SNR, for each manufacturer. This result suggests that there may be variations across manufacturers in processing various listening conditions. There was no significant effect of technology level. There was a small effect of pure-tone average on signal modification for one manufacturer, but no effect of audiogram slope. Finally, there was a broad range of measured signal modification for a given hearing loss, for the same manufacturer and listening condition.
The signal modification values in this study are representative of commonly fit hearing aids in clinics today. The results of this study provide insights into how the range of signal modifications obtained in real clinical fittings compares with a previous study. Future studies will focus on the behavioral implications of signal modifications in clinically fit hearing aids.
助听器提供了各种信号处理技术及一系列参数，以改善听力受损者的聆听体验。在先前的研究中，我们报告了市售助听器中轻度与强信号处理在信号修改方面存在显著差异。在本研究中，作者将这项工作扩展到基于最佳实践指南的临床定制助听器验配。该项目的目标是确定不同制造商和技术水平的临床验配助听器中累积信号修改的范围，以及包括信噪比（SNR）和呈现水平在内的聆听条件对这些信号修改的影响。
我们确定了一组代表典型临床环境的助听器。从三家听力诊所获取了成年感音神经性听力损失患者的匿名助听器验配数据，涵盖了一系列听力敏感度。用这些匿名验配数据对匹配的实验室助听器进行编程。在四个信噪比和三个呈现水平下记录这些助听器的输出。使用助听器言语质量指数的谐波相关分量对产生的信号修改进行量化，该指数在听力损失模型的背景下测量语音包络变化。这些度量值代表助听器使用者听到的助听器处理后的信号。听力测定信息用于确定与这些临床验配助听器中信号修改分布的任何可能关联的性质。
一般来说，信号修改随着信噪比降低和呈现水平提高而增加。不同制造商之间的差异显著，以至于每个制造商在每个信噪比下呈现水平的影响各不相同。这一结果表明，不同制造商在处理各种聆听条件时可能存在差异。技术水平没有显著影响。对于一个制造商，纯音平均值对信号修改有较小影响，但听力图斜率没有影响。最后，对于给定的听力损失，在相同的制造商和聆听条件下，测量到的信号修改范围很广。
本研究中的信号修改值代表了当今临床中常用的验配助听器。本研究结果提供了有关实际临床验配中获得的信号修改范围与先前研究相比情况的见解。未来的研究将专注于临床验配助听器中信号修改的行为学影响。
