Cochlear Efferent Feedback and Hearing-in-Noise Perception in Autism

描述(申请人提供)：在背景噪音中过滤相关听觉信息的困难是自闭症谱系障碍(ASD)的主要特征之一，这种过滤困难会显著损害一个人的社交能力。家长和老师经常报告说，自闭症儿童在嘈杂的环境中尤其难以注意和理解语言。这些观察结果得到了使用标准化问卷测量感觉功能的研究的支持。虽然患有自闭症的人在背景噪声中过滤语音信息有困难，但过滤能力可能存在变异性，并且这种变异性中的一些可能与以下处理有关：i)听觉目标(语音或非语音信号)，ii)听觉背景噪声(掩蔽型)，以及iii)听觉系统在空间上将目标与掩蔽者分开的能力(空间释放与掩蔽)。过滤相关听觉信息的能力的生理学基础被认为是由于中枢神经系统通过下行听觉通路--橄榄耳蜗传出系统--对耳蜗活动的调节。内侧橄榄耳蜗区(MOC)传出系统调节耳蜗外毛细胞的主动微机械收缩特性，进而调节内毛细胞传入放电频率。此外，可以在受试者身上评估外耳道的收缩活动，因为它们的收缩会产生声信号(耳声发射；OAEs)，这些信号可以被记录在外耳道中，从而可以直接测量耳蜗周的听觉过滤过程。先前的研究表明，患有自闭症的青少年和儿童使用短暂性耳声发射(TrOAE)可以降低MOC的传出反馈强度。在目标1中，我们将考察高功能自闭症青少年的听觉过滤和空间掩蔽释放能力，并以语音和音乐音调为目标，以语音形状和合成杂音为掩蔽者，研究高功能自闭症和典型发育对照青少年的听觉过滤和空间释放。我们将使用心理物理学和自适应跟踪来测量不同条件下的目标阈值，以评估ASD是否与言语特定听力任务的表现受损有关。在目标2中，我们将使用两种不同的基于耳声发射的测试来测量耳蜗MOC传出反馈强度：失真乘积OAEs(DPOAEs)和双耳宽带刺激下的瞬时OAEs(TrOAEs)，以最大限度地激活MOC传出反馈。我们将验证ASD患者MOC传出反馈强度和R/L耳对称性受损的假说。从这些研究中获得的信息将使我们能够确定传出反馈强度的非侵入性测量是否可以作为这种疾病中听觉过滤能力的生理指标。 与公共健康相关：这项研究将促进我们对自闭症患者如何在存在背景噪音的情况下听到语音的理解。这种过滤相关听觉信息的能力对言语感知和更广泛的语言社交使用至关重要。使用微型扬声器-麦克风耳塞，我们还将测量内耳感觉细胞产生的声音信号(耳声发射)，因为这些发射在背景噪声存在的情况下被抑制。我们将确定自闭症患者是否减少了噪音对这些辐射的抑制，以及这种自闭症特有的辐射差异是否与这一人群的听觉过滤能力有关。

DESCRIPTION (provided by applicant): Difficulty in filtering relevant auditory information in background noise is one of the key features of autism spectrum disorders (ASD) and such filtering difficulties can significantly impair a person's social communication abilities. Parents and teachers often report that children with autism have particular difficulty attending to and understanding speech in noisy environments. These observations are supported by studies using standardized questionnaires to measure sensory functioning. While people with ASD have difficulties filtering speech information in background noise, there may be variability in filtering abilities, and some of this variability maybe be related to processing of: i) the auditory target (speech or non-speech signals), ii) auditory background noise (masker type), and iii) the ability of the auditory system to spatially separate the target from the masker (spatial release from masking). The physiological basis for the ability to filter relevant auditory information is believed to be due to regulation of cochlear activity by the CNS via descending auditory pathways-the olivocochlear efferent system. The medial olivocochlear (MOC) efferent system mediates active micromechanical contractile properties of cochlear outer hair cells (OHCs) which then modulate inner hair cell afferent firing rates. Moreover, the contractile activity of the OHCs can be evaluated in human subjects, because their contractions generate acoustic signals (otoacoustic emissions; OAEs), which can be recorded in the external ear canal, making it possible to directly measure auditory filtering processes at the cochlear periphery. It has previously been shown that adolescents and children with ASD have reduced MOC efferent feedback strengths using transient OAEs (TrOAEs). In Aim 1, we will investigate auditory filtering and spatial release from masking ability in adolescents with high functioning autism and typically developing controls, using both speech and musical tones as targets, and both speech-shaped and synthesized babble noise as maskers. We will use psychophysics and adaptive tracking to measure target thresholds in the different conditions to evaluate whether ASD is associated with impaired performance on speech-specific listening tasks. In Aim 2, we will measure cochlear MOC efferent feedback strength using two different otoacoustic emission-based tests: distortion-product OAEs (DPOAEs) and transient OAEs (TrOAEs) with binaural broadband stimulation to maximally activate MOC efferent feedback. We will test the hypothesis that MOC efferent feedback strength and R/L ear symmetry is impaired in ASD. Information gained from these studies will allow us to determine if a non-invasive measure of efferent feedback strength can serve as a physiological indicator of auditory filtering capabilities in this disorder. PUBLIC HEALTH RELEVANCE: This research will advance our understanding of how individuals with autism can hear speech sounds in the presence of background noise. This ability to filter relevant auditory information is critical for speech perception and the social use of language more generally. Using miniature speaker-microphone earplugs, we will also measure acoustic signals (otoacoustic emissions) generated by sensory cells in the inner ear as these emissions are suppressed in the presence of background noise. We will determine if individuals with autism have reduced noise-induced suppression of these emissions, and if such autism-specific differences in emissions are related to auditory filtering capabilities in this population.