Academic Medical Center Amsterdam, Department of Clinical and Experimental Audiology, Meibergdreef, Amsterdam, The Netherlands.
Ear Hear. 2013 Jan-Feb;34(1):29-41. doi: 10.1097/AUD.0b013e31825f299f.
Most modern hearing aids use noise reduction to increase listening comfort in noisy environments. However, it is unclear whether perceptual effects (e.g., intelligibility, listening effort, and preference) of noise reduction differ among hearing aids and among listeners. The authors compared perceptual scores across different hearing aid noise-reduction systems to determine (1) whether noise-reduction systems differ perceptually and (2) which factors underlie the overall preference of individual listeners.
The authors recorded hearing aid noise-reduction outputs and used these signals in a laboratory experiment. The recording method allowed the evaluation of noise reduction in an isolated form, without the dominant effects of hearing aid frequency response and interactions with dynamic-range compression. Ten normal-hearing subjects listened to speech in babble noise processed by noise reduction from four different hearing aids. The subjects performed (1) speech-intelligibility tests, (2) listening-effort ratings, and (3) paired-comparison ratings with respect to noise annoyance, speech naturalness, and overall preference.
Noise-reduction systems from different hearing aids differed in the degree to which they influenced the noise annoyance and speech naturalness perceived by the normal-hearing listeners. Small differences in intelligibility and effort scores were found among different noise-reduction systems but not between having noise reduction on and off. Subjects differed in whether their overall preference was more strongly related to noise annoyance or to speech naturalness.
The authors conclude that noise annoyance and speech naturalness are determining factors for the overall preference of normal-hearing listeners for a specific noise-reduction condition, and found individual differences in the preferred weighting of these factors even in a homogeneous group of normal-hearing listeners. Subsequent experiments should include hearing-impaired subjects to determine whether these conclusions also hold for a more heterogeneous group of listeners. If these results can be extrapolated to hearing-impaired listeners, the fitting and fine-tuning of noise reduction in hearing aids needs considerable revision.
大多数现代助听器采用降噪技术来提高在噪声环境中的聆听舒适度。然而，目前尚不清楚不同助听器和不同聆听者之间的降噪的感知效果（例如可懂度、聆听努力程度和偏好）是否存在差异。作者比较了不同助听器降噪系统的感知评分，以确定（1）降噪系统在感知上是否存在差异，以及（2）哪些因素是个体聆听者整体偏好的基础。
作者记录了助听器降噪输出，并在实验室实验中使用这些信号。该记录方法允许以孤立的形式评估降噪，而不受助听器频率响应和与动态范围压缩相互作用的主要影响。10 名正常听力受试者在噪声中听取了言语，这些噪声是由四种不同助听器的降噪处理的。受试者进行了（1）言语可懂度测试、（2）聆听努力程度评分，以及（3）针对噪声烦恼、言语自然度和整体偏好的配对比较评分。
来自不同助听器的降噪系统在对正常听力聆听者感知到的噪声烦恼和言语自然度的影响程度上存在差异。不同降噪系统之间的可懂度和努力程度评分存在较小差异，但在开启和关闭降噪之间没有差异。受试者的整体偏好与噪声烦恼或言语自然度的相关性更强，这存在个体差异。
作者得出结论，噪声烦恼和言语自然度是正常听力聆听者对特定降噪条件整体偏好的决定因素，并且在正常听力聆听者中，即使在同质组中，也存在这些因素的偏好权重的个体差异。后续实验应包括听力受损受试者，以确定这些结论是否也适用于更异构的聆听者群体。如果这些结果可以外推到听力受损的听众，那么助听器中降噪的适配和微调需要进行重大修订。
