Maruthy Sandeep, Kumar U Ajith, Gnanateja G Nike
Electrophysiology Laboratory, Department of Audiology, All India Institute of Speech and Hearing, Manasagangothri, Mysore, Karnataka, IN-570006, India.
J Assoc Res Otolaryngol. 2017 Aug;18(4):635-648. doi: 10.1007/s10162-017-0623-y. Epub 2017 Apr 26.
Efferent modulation has been demonstrated to be very important for speech perception, especially in the presence of noise. We examined the functional relationship between two efferent systems: the rostral and caudal efferent pathways and their individual influences on speech perception in noise. Earlier studies have shown that these two efferent mechanisms were correlated with speech perception in noise. However, previously, these mechanisms were studied in isolation, and their functional relationship with each other was not investigated. We used a correlational design to study the relationship if any, between these two mechanisms in young and old normal hearing individuals. We recorded context-dependent brainstem encoding as an index of rostral efferent function and contralateral suppression of otoacoustic emissions as an index of caudal efferent function in groups with good and poor speech perception in noise. These efferent mechanisms were analysed for their relationship with each other and with speech perception in noise. We found that the two efferent mechanisms did not show any functional relationship. Interestingly, both the efferent mechanisms correlated with speech perception in noise and they even emerged as significant predictors. Based on the data, we posit that the two efferent mechanisms function relatively independently but with a common goal of fine-tuning the afferent input and refining auditory perception in degraded listening conditions.
传出调制已被证明对言语感知非常重要，尤其是在存在噪声的情况下。我们研究了两个传出系统之间的功能关系：延髓传出通路和尾侧传出通路，以及它们各自对噪声环境下言语感知的影响。早期研究表明，这两种传出机制与噪声环境下的言语感知相关。然而，以前这些机制是单独研究的，它们之间的功能关系并未被探究。我们采用相关设计来研究年轻和老年听力正常个体中这两种机制之间是否存在关系。我们将与上下文相关的脑干编码记录为延髓传出功能的指标，将对侧耳声发射抑制记录为尾侧传出功能的指标，这些个体在噪声环境下的言语感知能力有好有差。我们分析了这些传出机制之间的关系以及它们与噪声环境下言语感知的关系。我们发现这两种传出机制之间没有显示出任何功能关系。有趣的是，这两种传出机制都与噪声环境下的言语感知相关，甚至成为显著的预测指标。基于这些数据，我们认为这两种传出机制相对独立地发挥作用，但有着共同的目标，即在听力条件下降时对传入输入进行微调并优化听觉感知。
