National Military Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, Maryland 20889, USA.
Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio 45433, USA.
J Acoust Soc Am. 2020 Jan;147(1):446. doi: 10.1121/10.0000511.
For single-sided deafness cochlear-implant (SSD-CI) listeners, different peripheral representations for electric versus acoustic stimulation, combined with interaural frequency mismatch, might limit the ability to perceive bilaterally presented speech as a single voice. The assessment of binaural fusion often relies on subjective report, which requires listeners to have some understanding of the perceptual phenomenon of object formation. Two experiments explored whether binaural fusion could instead be assessed using judgments of the number of voices in a mixture. In an SSD-CI simulation, normal-hearing listeners were presented with one or two "diotic" voices (i.e., unprocessed in one ear and noise-vocoded in the other) in a mixture with additional monaural voices. In experiment 1, listeners reported how many voices they heard. Listeners generally counted the diotic speech as two separate voices, regardless of interaural frequency mismatch. In experiment 2, listeners identified which of two mixtures contained diotic speech. Listeners performed significantly better with interaurally frequency-matched than with frequency-mismatched stimuli. These contrasting results suggest that listeners experienced partial fusion: not enough to count the diotic speech as one voice, but enough to detect its presence. The diotic-speech detection task (experiment 2) might provide a tool to evaluate fusion and optimize frequency mapping for SSD-CI patients.
对于单侧聋（SSD）人工耳蜗植入（CI）患者，电刺激和声学刺激的不同外周表示形式，加上耳间频率不匹配，可能会限制对双侧呈现的语音感知为单个声音的能力。双耳融合的评估通常依赖于主观报告，这要求听者对物体形成的感知现象有一定的了解。两项实验探讨了是否可以使用混合语音中声音数量的判断来评估双耳融合。在 SSD-CI 模拟中，正常听力的听者在混合了额外的单声道语音的情况下，听到一个或两个“同相”语音（即一个耳朵未处理，另一个耳朵噪声编码）。在实验 1 中，听者报告他们听到的声音数量。听者通常将同相语音数为两个独立的声音，而不考虑耳间频率不匹配。在实验 2 中，听者识别两个混合物中哪一个包含同相语音。与耳间频率匹配的刺激相比，听者在频率不匹配的刺激下表现明显更好。这些对比结果表明，听者经历了部分融合：不足以将同相语音数为一个声音，但足以检测其存在。同相语音检测任务（实验 2）可能为评估融合和优化 SSD-CI 患者的频率映射提供工具。
