Department of Otolaryngology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
Department of Audiology, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Neurol Sci. 2020 Mar;41(3):611-617. doi: 10.1007/s10072-019-04102-z. Epub 2019 Nov 15.
Sound lateralization/localization is one of the most important auditory processing abilities, which plays approved role in auditory streaming and speech perception in challenging situations like noisy places. In addition to the main role of lower brainstem centers like superior olivary complex in sound lateralization, efferent auditory system effects on improving auditory skills in everyday auditory challenging positions were revealed. This study evaluated noise effects on lateralization scores in correlation with an objective electrophysiologic test (Speech-ABR in noise), which objectively shows cumulative effects of the afferent and efferent auditory systems at the inferior colliculus and upper brainstem pathway.
Fourteen normal-hearing subjects in the age range of 18 to 25 participated in this study. Lateralization scores in the quiet and noisy modes were evaluated. Speech-ABR in both ears for quiet mode and three different contralateral noise levels (SNR = + 5, 0, - 5) were recorded, too. Correlation of lateralization scores and Speech-ABR changes in noise was studied.
Significant decrease of lateralization scores with latency increase and amplitude decrease of Speech-ABR transient peaks (V, A, O) was seen with noise presentation. A high positive correlation between lateralization decrease with latency increase of onset peaks (V, A) and amplitude decrease of transient peaks (V, A, O) was found in low signal-to-noise ratios.
The study revealed that in high challenging auditory situations like auditory lateralization in noise, upper brainstem centers and pathways play a facilitative role for main auditory lateralization centers in lower levels.
声音的侧化/定位是最重要的听觉处理能力之一，在嘈杂环境等具有挑战性的情况下，对听觉流和语音感知起着重要作用。除了下脑桥中心（如上橄榄复合体）在声音侧化中的主要作用外，传出听觉系统对改善日常听觉挑战环境中的听觉技能也有影响。本研究评估了噪声对侧化评分的影响，同时进行了一项客观电生理测试（噪声中的言语 ABR），该测试客观地显示了传入和传出听觉系统在下丘和上脑桥通路的累积效应。
14 名听力正常的受试者年龄在 18 至 25 岁之间，参与了这项研究。评估了安静和嘈杂模式下的侧化评分。还记录了双耳在安静模式和三种不同对侧噪声水平（信噪比=+5、0、-5）下的言语 ABR。研究了侧化评分与噪声中 Speech-ABR 变化的相关性。
随着噪声的出现，Speech-ABR 瞬态峰（V、A、O）的潜伏期延长和振幅降低，侧化评分显著降低。在低信噪比下，起始峰（V、A）潜伏期延长和瞬态峰（V、A、O）振幅降低与侧化评分降低之间存在高度正相关。
本研究表明，在高挑战性的听觉环境中，如噪声中的听觉侧化，上脑桥中心和通路对上脑桥中的主要听觉侧化中心发挥促进作用。
