Subjective reports indicate that hearing aids can disrupt sound externalization and/or reduce the perceived distance of sounds. Here we conducted an experiment to explore this phenomenon and to quantify how frequently it occurs for different hearing-aid styles. Of particular interest were the effects of microphone position (behind the ear vs. in the ear) and dome type (closed vs. open). Participants were young adults with normal hearing or with bilateral hearing loss, who were fitted with hearing aids that allowed variations in the microphone position and the dome type. They were seated in a large sound-treated booth and presented with monosyllabic words from loudspeakers at a distance of 1.5 m. Their task was to rate the perceived externalization of each word using a rating scale that ranged from 10 (at the loudspeaker in front) to 0 (in the head) to −10 (behind the listener). On average, compared to unaided listening, hearing aids tended to reduce perceived distance and lead to more in-the-head responses. This was especially true for closed domes in combination with behind-the-ear microphones. The behavioral data along with acoustical recordings made in the ear canals of a manikin suggest that increased low-frequency ear-canal levels (with closed domes) and ambiguous spatial cues (with behind-the-ear microphones) may both contribute to breakdowns of externalization.

中文翻译：

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使用助听器聆听时言语的外化


主观报告表明助听器会破坏声音的外化和/或减少声音的感知距离。在这里，我们进行了一项实验来探索这种现象，并量化不同助听器样式发生这种现象的频率。特别令人感兴趣的是麦克风位置（耳后与耳内）和圆顶类型（封闭与开放）的影响。参与者是听力正常或双侧听力损失的年轻人，他们配备了允许改变麦克风位置和圆顶类型的助听器。他们坐在一个经过隔音处理的大型展位上，距离 1.5 m 的扬声器播放单音节单词。他们的任务是使用范围从 10（前面的扬声器）到 0（在头部）到 -10（在听众后面）的评级量表来评估每个单词的感知外化。平均而言，与裸听相比，助听器往往会缩短感知距离并导致更多的头脑反应。对于与耳后式麦克风结合的封闭式圆顶麦克风尤其如此。行为数据以及人体模型耳道中的声学记录表明，增加的低频耳道水平（带有封闭的圆顶）和模糊的空间线索（带有耳后麦克风）都可能导致外化的崩溃。