Park Min-Hyun, Won Jong Ho, Horn David L, Rubinstein Jay T
Department of Otorhinolaryngology, Boramae Medical Center, Seoul Metropolitan Government - Seoul National University, Seoul, 156-707, Korea.
J Assoc Res Otolaryngol. 2015 Jun;16(3):389-99. doi: 10.1007/s10162-014-0499-z. Epub 2015 Mar 20.
Temporal modulation detection ability matures over many years after birth and may be particularly sensitive to experience during this period. Profound hearing loss during early childhood might result in greater perceptual deficits than a similar loss beginning in adulthood. We tested this idea by measuring performance in temporal modulation detection in profoundly deaf children and adults fitted with cochlear implants (CIs). At least two independent variables could constrain temporal modulation detection performance in children with CIs: altered encoding of modulation information due to the CI-auditory nerve interface, and atypical development of central processing of sound information provided by CIs. The effect of altered encoding was investigated by testing subjects with one of two different hearing mechanisms (normal hearing vs. CI) and the effect of atypical development was studied by testing two different age groups. All subjects were tested for their ability to detect acoustic temporal modulations of sound amplitude. A comparison of the slope, or cutoff frequency, of the temporal modulation transfer functions (TMTFs) among the four subject groups revealed that temporal resolution was mainly constrained by hearing mechanism: normal-hearing listeners could detect smaller amplitude modulations at high modulation frequencies than CI users. In contrast, a comparison of the height of the TMTFs revealed a significant interaction between hearing mechanism and age group on overall sensitivity to temporal modulation: sensitivity was significantly poorer in children with CIs, relative to the other three groups. Results suggest that there is an age-specific vulnerability of intensity discrimination or non-sensory factors, which subsequently affects sensitivity to temporal modulation in prelingually deaf children who use CIs.
颞调制检测能力在出生后的许多年里逐渐成熟，在此期间可能对经验特别敏感。幼儿期的重度听力损失可能比成年期开始的类似听力损失导致更大的感知缺陷。我们通过测量植入人工耳蜗（CI）的重度失聪儿童和成人的颞调制检测表现来验证这一观点。至少有两个自变量可能会限制CI儿童的颞调制检测表现：由于CI - 听觉神经接口导致的调制信息编码改变，以及CI提供的声音信息的中枢处理的非典型发育。通过用两种不同听力机制之一（正常听力与CI）测试受试者来研究编码改变的影响，并通过测试两个不同年龄组来研究非典型发育的影响。所有受试者都接受了检测声音幅度的声学颞调制的能力测试。对四个受试者组之间的颞调制传递函数（TMTF）的斜率或截止频率进行比较，结果表明时间分辨率主要受听力机制的限制：正常听力的听众在高调制频率下能够检测到比CI使用者更小幅度的调制。相比之下，对TMTF高度的比较揭示了听力机制和年龄组之间在对颞调制的总体敏感性上存在显著的相互作用：与其他三组相比，CI儿童的敏感性明显较差。结果表明，强度辨别或非感觉因素存在年龄特异性的脆弱性，这随后会影响使用CI的语前聋儿童对颞调制的敏感性。
