Marrufo-Pérez Miriam I, Eustaquio-Martín Almudena, Fumero Milagros J, Gorospe José M, Polo Rubén, Gutiérrez Revilla Auxiliadora, Lopez-Poveda Enrique A
Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain.
Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain; Departamento de Cirugía, Universidad de Salamanca, Salamanca, Spain; Servicio de Otorrinolaringología, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain.
Hear Res. 2019 Jun;377:133-141. doi: 10.1016/j.heares.2019.03.017. Epub 2019 Mar 22.
The detection of amplitude modulation (AM) in quiet or in noise improves when the AM carrier is preceded by noise, an effect that has been attributed to the medial olivocochlear reflex (MOCR). We investigate whether this improvement can occur without the MOCR by measuring AM sensitivity for cochlear implant (CI) users, whose MOCR effects are circumvented as a result of the electrical stimulation provided by the CI. AM detection thresholds were measured monaurally for short (50 ms) AM probes presented at the onset (early condition) or delayed by 300 ms (late condition) from the onset of a broadband noise. The noise was presented ipsilaterally, contralaterally and bilaterally to the test ear. Stimuli were processed through an experimental, time-invariant sound processing strategy. On average, thresholds were 4 dB better in the late than in the early condition and the size of the improvement was similar for the three noise lateralities. The pattern and magnitude of the improvement was broadly consistent with that for normal hearing listeners [Marrufo-Pérez et al., 2018, J Assoc Res Otolaryngol 19:147-161]. Because the electrical stimulation provided by CIs is independent from the middle-ear muscle reflex (MEMR) or the MOCR, this shows that mechanisms other than the MEMR or the MOCR can facilitate AM detection in noisy backgrounds.
当调幅（AM）载波之前存在噪声时，在安静环境或噪声环境中对调幅的检测会得到改善，这种效应被认为归因于内侧橄榄耳蜗反射（MOCR）。我们通过测量人工耳蜗（CI）使用者的调幅敏感度来研究在没有MOCR的情况下这种改善是否会发生，由于CI提供的电刺激，CI使用者的MOCR效应被规避。对在宽带噪声开始时呈现的短（50毫秒）调幅探测信号进行单耳测量调幅检测阈值，探测信号在开始时（早期条件）呈现，或者从宽带噪声开始延迟300毫秒（晚期条件）呈现。噪声分别向测试耳的同侧、对侧和双侧呈现。刺激信号通过一种实验性的、时不变的声音处理策略进行处理。平均而言，晚期条件下的阈值比早期条件下低4分贝，并且对于三种噪声方位，改善的幅度相似。这种改善的模式和幅度与正常听力的听众大致一致[Marrufo-Pérez等人，2018年，《耳鼻咽喉研究协会杂志》19:147 - 161]。由于CI提供的电刺激独立于中耳肌肉反射（MEMR）或MOCR，这表明除了MEMR或MOCR之外的机制可以促进在嘈杂背景下的调幅检测。
