Henry Ford Health System, Detroit, MI.
Waisman Center, University of Wisconsin-Madison, Madison, WI.
J Am Acad Audiol. 2020 Mar;31(3):195-208. doi: 10.3766/jaaa.18092. Epub 2019 Aug 12.
Spatial hearing abilities in children with bilateral cochlear implants (BiCIs) are typically improved when two implants are used compared with a single implant. However, even with BiCIs, spatial hearing is still worse compared to normal-hearing (NH) age-matched children. Here, we focused on children who were younger than three years, hence in their toddler years. Prior research with this age focused on measuring discrimination of sounds from the right versus left.
This study measured both discrimination and sound location identification in a nine-alternative forced-choice paradigm using the "reaching for sound" method, whereby children reached for sounding objects as a means of capturing their spatial hearing abilities.
Discrimination was measured with sounds randomly presented to the left versus right, and loudspeakers at fixed angles ranging from ±60° to ±15°. On a separate task, sound location identification was measured for locations ranging from ±60° in 15° increments.
Thirteen children with BiCIs (27-42 months old) and fifteen age-matched (NH).
Discrimination and sound localization were completed for all subjects. For the left-right discrimination task, participants were required to reach a criterion of 4/5 correct trials (80%) at each angular separation prior to beginning the localization task. For sound localization, data was analyzed in two ways. First, percent correct scores were tallied for each participant. Second, for each participant, the root-mean-square-error was calculated to determine the average distance between the response and stimulus, indicative of localization accuracy.
All BiCI users were able to discriminate left versus right at angles as small as ±15° when listening with two implants; however, performance was significantly worse when listening with a single implant. All NH toddlers also had >80% correct at ±15°. Sound localization results revealed root-mean-square errors averaging 11.15° in NH toddlers. Children in the BiCI group were generally unable to identify source location on this complex task (average error 37.03°).
Although some toddlers with BiCIs are able to localize sound in a manner consistent with NH toddlers, for the majority of toddlers with BiCIs, sound localization abilities are still emerging.
与单侧人工耳蜗植入相比，双侧人工耳蜗植入（BiCIs）可显著改善儿童的空间听觉能力。然而，即使使用 BiCIs，儿童的空间听觉能力仍不如正常听力（NH）的同龄儿童。在这里，我们关注的是三岁以下的儿童，即幼儿时期。先前对这一年龄段的研究主要集中在测量左右声源的辨别能力上。
本研究采用“伸手取声”的方法，通过儿童伸手去抓发声物体的方式，在九项选择的强制选择范式中测量辨别力和声音位置识别能力。该方法使用左右随机声源和固定角度（±60°至±15°）的扬声器。在另一项任务中，通过 15°增量测量 ±60°范围内的声音位置识别。
13 名双侧人工耳蜗植入儿童（27-42 个月）和 15 名年龄匹配的正常听力儿童。
所有受试者均完成了辨别力和声音定位测试。在左右辨别任务中，参与者需要在每个角度间隔达到 4/5 的正确试验（80%），才能开始进行定位任务。对于声音定位，数据通过两种方式进行分析。首先，对每个参与者的正确百分比进行计数。其次，对于每个参与者，计算均方根误差，以确定反应和刺激之间的平均距离，指示定位精度。
当使用两个植入体聆听时，所有 BiCI 用户都能够辨别出角度小至±15°的左右声源；然而，当使用单个植入体聆听时，表现明显更差。所有 NH 幼儿在±15°时的正确率也超过 80%。声音定位结果显示，NH 幼儿的均方根误差平均为 11.15°。BiCI 组的儿童通常无法在这项复杂任务中识别声源位置（平均误差为 37.03°）。
尽管一些双侧人工耳蜗植入的幼儿能够以类似于 NH 幼儿的方式定位声音，但对于大多数双侧人工耳蜗植入的幼儿来说，声音定位能力仍在发展中。
