Harvard/Massachusetts Institute of Technology, Speech and Hearing Bioscience and Technology Program, Cambridge, Massachusetts 02139, USA.
J Acoust Soc Am. 2013 Apr;133(4):2329-39. doi: 10.1121/1.4794386.
Many hearing aids introduce compressive gain to accommodate the reduced dynamic range that often accompanies hearing loss. However, natural sounds produce complicated temporal dynamics in hearing aid compression, as gain is driven by whichever source dominates at a given moment. Moreover, independent compression at the two ears can introduce fluctuations in interaural level differences (ILDs) important for spatial perception. While independent compression can interfere with spatial perception of sound, it does not always interfere with localization accuracy or speech identification. Here, normal-hearing listeners reported a target message played simultaneously with two spatially separated masker messages. We measured the amount of spatial separation required between the target and maskers for subjects to perform at threshold in this task. Fast, syllabic compression that was independent at the two ears increased the required spatial separation, but linking the compressors to provide identical gain to both ears (preserving ILDs) restored much of the deficit caused by fast, independent compression. Effects were less clear for slower compression. Percent-correct performance was lower with independent compression, but only for small spatial separations. These results may help explain differences in previous reports of the effect of compression on spatial perception of sound.
许多助听器采用压缩增益来适应听力损失常伴有的动态范围缩小。然而，在助听器压缩中，自然声音产生复杂的时间动态，因为增益是由给定时刻主导的源驱动的。此外，双耳独立压缩会导致对空间感知很重要的耳间强度差 (ILD) 波动。虽然独立压缩会干扰声音的空间感知，但它并不总是干扰定位准确性或语音识别。在这里，正常听力的听众报告了一个目标消息与两个空间分离的掩蔽消息同时播放。我们测量了在这项任务中，受试者在阈值下执行的目标和掩蔽消息之间所需的空间分离量。快速、音节独立的压缩会增加所需的空间分离，但将压缩机连接起来为两只耳朵提供相同的增益（保持 ILD），可以恢复快速、独立压缩造成的大部分缺陷。对于较慢的压缩，效果不太明显。独立压缩时的正确百分比较低，但仅在较小的空间分离时如此。这些结果可能有助于解释以前关于压缩对声音空间感知影响的报告中的差异。
