King Andrew, Hopkins Kathryn, Plack Christopher J, Pontoppidan Niels Henrik, Bramsløw Lars, Hietkamp Renskje K, Vatti Marianna, Hafez Atefeh
Manchester Centre for Audiology and Deafness, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom.
Eriksholm Research Centre, Oticon A/S, Rørtangvej 20, Snekkersten, Denmark.
J Acoust Soc Am. 2017 Apr;141(4):2591. doi: 10.1121/1.4979593.
Old, hearing-impaired listeners generally benefit little from lateral separation of multiple talkers when listening to one of them. This study aimed to determine how spatial release from masking (SRM) in such listeners is affected when the interaural time differences (ITDs) in the temporal fine structure (TFS) are manipulated by tone-vocoding (TVC) at the ears by a master hearing aid system. Word recall was compared, with and without TVC, when target and masker sentences from a closed set were played simultaneously from the front loudspeaker (co-located) and when the maskers were played 45° to the left and right of the listener (separated). For 20 hearing-impaired listeners aged 64 to 86, SRM was 3.7 dB smaller with TVC than without TVC. This difference in SRM correlated with mean audiometric thresholds below 1.5 kHz, even when monaural TFS sensitivity (discrimination of frequency-shifts in identically filtered complexes) was partialed out, suggesting that low-frequency audiometric thresholds may be a good indicator of candidacy for hearing aids that preserve ITDs. The TVC difference in SRM was not correlated with age, pure-tone ITD thresholds, nor fundamental frequency difference limens, and only with monaural TFS sensitivity before control for low-frequency audiometric thresholds.
年老的听力受损听众在收听多个讲话者中的一个时，通常从多个讲话者的横向分离中获益甚微。本研究旨在确定当主助听器系统通过音调编码（TVC）在双耳处操纵颞部精细结构（TFS）中的双耳时间差（ITD）时，此类听众的空间掩蔽释放（SRM）会受到怎样的影响。当来自封闭集合的目标句和掩蔽句从前方扬声器同时播放（共置）以及掩蔽句在听众左右两侧45°处播放（分离）时，比较了有无TVC情况下的单词回忆情况。对于20名年龄在64至86岁的听力受损听众，有TVC时的SRM比无TVC时小3.7dB。即使在去除单耳TFS敏感性（相同滤波复合体中频率偏移的辨别）后，SRM的这种差异仍与1.5kHz以下的平均听力阈值相关，这表明低频听力阈值可能是适合保留ITD的助听器的良好候选指标。SRM中的TVC差异与年龄、纯音ITD阈值、基频差异阈均无关联，仅在控制低频听力阈值之前与单耳TFS敏感性有关。
