Rasetshwane Daniel M, Raybine David A, Kopun Judy G, Gorga Michael P, Neely Stephen T
Center for Hearing Research, Boys Town National Research Hospital, Omaha, NE.
J Am Acad Audiol. 2019 Jan;30(1):16-30. doi: 10.3766/jaaa.16165. Epub 2017 Dec 15.
In listening environments with background noise that fluctuates in level, listeners with normal hearing can "glimpse" speech during dips in the noise, resulting in better speech recognition in fluctuating noise than in steady noise at the same overall level (referred to as masking release). Listeners with sensorineural hearing loss show less masking release. Amplification can improve masking release but not to the same extent that it does for listeners with normal hearing.
The purpose of this study was to compare masking release for listeners with sensorineural hearing loss obtained with an experimental hearing-aid signal-processing algorithm with instantaneous compression (referred to as a suppression hearing aid, SHA) to masking release obtained with fast compression. The suppression hearing aid mimics effects of normal cochlear suppression, i.e., the reduction in the response to one sound by the simultaneous presentation of another sound.
A within-participant design with repeated measures across test conditions was used.
Participants included 29 adults with mild-to-moderate sensorineural hearing loss and 21 adults with normal hearing.
Participants with sensorineural hearing loss were fitted with simulators for SHA and a generic hearing aid (GHA) with fast (but not instantaneous) compression (5 ms attack and 50 ms release times) and no suppression. Gain was prescribed using either an experimental method based on categorical loudness scaling (CLS) or the Desired Sensation Level (DSL) algorithm version 5a, resulting in a total of four processing conditions: CLS-GHA, CLS-SHA, DSL-GHA, and DSL-SHA.
All participants listened to consonant-vowel-consonant nonwords in the presence of temporally-modulated and steady noise. An adaptive-tracking procedure was used to determine the signal-to-noise ratio required to obtain 29% and 71% correct. Measurements were made with amplification for participants with sensorineural hearing loss and without amplification for participants with normal hearing.
Repeated-measures analysis of variance was used to determine the influence of within-participant factors of noise type and, for participants with sensorineural hearing loss, processing condition on masking release. Pearson correlational analysis was used to assess the effect of age on masking release for participants with sensorineural hearing loss.
Statistically significant masking release was observed for listeners with sensorineural hearing loss for 29% correct, but not for 71% correct. However, the amount of masking release was less than masking release for participants with normal hearing. There were no significant differences among the amplification conditions for participants with sensorineural hearing loss.
The results suggest that amplification with either instantaneous or fast compression resulted in similar masking release for listeners with sensorineural hearing loss. However, the masking release was less for participants with hearing loss than it was for those with normal hearing.
在背景噪声水平波动的聆听环境中，听力正常的聆听者能够在噪声低谷时“捕捉”到言语，从而在波动噪声环境下比在相同总体水平的稳态噪声环境中具有更好的言语识别能力（称为掩蔽解脱）。感音神经性听力损失的聆听者表现出较少的掩蔽解脱。放大可以改善掩蔽解脱，但改善程度不及听力正常的聆听者。
本研究的目的是比较使用具有瞬时压缩功能的实验性助听器信号处理算法（称为抑制型助听器，SHA）为感音神经性听力损失聆听者获得的掩蔽解脱与使用快速压缩获得的掩蔽解脱。抑制型助听器模拟正常耳蜗抑制的效果，即通过同时呈现另一种声音来降低对一种声音的反应。
采用在测试条件间进行重复测量的被试内设计。
参与者包括29名轻度至中度感音神经性听力损失的成年人和21名听力正常的成年人。
为感音神经性听力损失的参与者佩戴SHA模拟器和具有快速（但非瞬时）压缩功能（启动时间5毫秒，释放时间50毫秒）且无抑制功能的通用助听器（GHA）。使用基于分类响度标度（CLS）的实验方法或期望感觉级（DSL）算法版本5a来规定增益，从而产生总共四种处理条件：CLS-GHA、CLS-SHA、DSL-GHA和DSL-SHA。
所有参与者在存在时间调制噪声和稳态噪声的情况下聆听辅音-元音-辅音非词。采用自适应跟踪程序来确定获得29%和71%正确识别率所需的信噪比。对感音神经性听力损失的参与者进行放大测量，对听力正常的参与者不进行放大测量。
采用重复测量方差分析来确定被试内因素噪声类型以及对于感音神经性听力损失的参与者，处理条件对掩蔽解脱的影响。采用Pearson相关分析来评估年龄对感音神经性听力损失参与者掩蔽解脱的影响。
对于感音神经性听力损失的聆听者，在29%正确识别率时观察到具有统计学意义的掩蔽解脱，但在71%正确识别率时未观察到。然而，掩蔽解脱的量小于听力正常参与者的掩蔽解脱量。感音神经性听力损失参与者的放大条件之间没有显著差异。
结果表明，对于感音神经性听力损失的聆听者，使用瞬时或快速压缩进行放大产生的掩蔽解脱效果相似。然而，听力损失参与者的掩蔽解脱比听力正常参与者的要少。
