School of Psychological Sciences, The University of Manchester, Manchester, United Kingdom.
Ear Hear. 2013 Jul-Aug;34(4):458-69. doi: 10.1097/AUD.0b013e3182775982.
The presence of cochlear dead regions (DRs) can have a significant effect on speech perception. Some studies have reported that adults do not benefit from amplification of frequencies well inside an extensive DR. However, the importance of high-frequency amplification for hearing-impaired children has been emphasized by many researchers. This study investigates the benefit of high-frequency amplification for children with various degrees of high-frequency hearing impairment, with and without DRs.
The children, aged 8 to 13 years, were divided into two groups according to the severity of their hearing impairment. Group MS had moderate to severe impairment (9 ears without DRs and 3 ears with restricted DRs). Group SP had severe to profound hearing impairment (7 ears with DRs and 1 ear without a DR). The vowel-consonant-vowel stimuli were subjected to the frequency-gain characteristics prescribed by the desired sensation level fitting method and presented via headphones broadband and under various low-pass filtering conditions.
Group MS benefited from high-frequency amplification whether or not a restricted DR was present. In contrast, ears in group SP with continuous extensive DRs showed limited benefit from high-frequency amplification. For the latter, performance improved with increasing cutoff frequency up to approximately 1 octave above the edge frequency of the DR and generally stayed the same, or deteriorated, with further increases in bandwidth. In one case of severe to profound hearing impairment without evidence of DRs, performance increased with increasing cutoff frequency up to 2 kHz and remained almost constant with further increases in bandwidth.
For children with severe to profound hearing impairment and continuous high-frequency DRs commencing from approximately 1 kHz, applying amplification only for frequencies up to approximately 1 octave above the edge frequency of the DR may be of benefit. Tests with more participants are needed to confirm this finding.
耳蜗死区（DR）的存在会对言语感知产生重大影响。一些研究报告称，成年人无法从广泛 DR 内的频率放大中受益。然而，许多研究人员强调了高频放大对听力受损儿童的重要性。本研究调查了高频放大对不同程度高频听力损失儿童的益处，包括有无 DR。
8 至 13 岁的儿童根据听力损失的严重程度分为两组。MS 组为中度至重度听力损失（9 耳无 DR，3 耳 DR 受限）。SP 组为重度至极重度听力损失（7 耳有 DR，1 耳无 DR）。元音-辅音-元音刺激物采用所需感觉水平拟合方法规定的频率增益特性，并通过耳机宽带呈现，并在各种低通滤波条件下呈现。
无论是否存在受限 DR，MS 组都从高频放大中受益。相比之下，SP 组中耳连续广泛的 DR 显示出对高频放大的有限益处。对于后者，随着截止频率的增加（增加到 DR 边缘频率的 1 个倍频程以上），性能会有所提高，并且带宽进一步增加时，性能通常保持不变或恶化。在一例无 DR 的严重至极重度听力损失中，随着截止频率增加到 2 kHz，性能增加，并且随着带宽的进一步增加，性能几乎保持不变。
对于从大约 1 kHz 开始有连续高频 DR 的重度至极重度听力损失儿童，仅对截止频率大约 1 个倍频程以上的频率进行放大可能是有益的。需要更多参与者的测试来证实这一发现。
