Department of Speech, Language and Hearing Sciences, Boston University, Boston, MA 02215, USA.
Trends Hear. 2024 Jan-Dec;28:23312165241229572. doi: 10.1177/23312165241229572.
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.
主观报告表明，助听器可能会干扰声音的外化和/或降低声音的感知距离。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。特别感兴趣的是麦克风位置（耳后与耳内）和耳模类型（封闭与开放）的影响。参与者为听力正常或双侧听力损失的年轻人，他们佩戴了允许改变麦克风位置和耳模类型的助听器。他们坐在一个大型隔音的播音室内，从距离 1.5 米的扬声器中听到单音节单词。他们的任务是使用从 10（在扬声器前）到 0（在头部）到-10（在听众后面）的评分量表来评价每个单词的感知外化程度。与未佩戴助听器相比，助听器通常会降低感知距离，并导致更多的头部内响应。对于封闭耳模与耳后麦克风的组合尤其如此。行为数据以及对人体模型耳道内的录音表明，低频耳道水平的增加（封闭耳模）和空间线索的模糊性（耳后麦克风）都可能导致声音外化的破坏。
