AUDITORY NEURAL CODING OF SPEECH

描述：（改编自研究者摘要） 对话发生在竞争的声音，如其他声音或 环境噪音。听力受损的人经常抱怨困难 即使他们在安静的环境中也能很好地理解噪音背景下的言语。而 生理机制潜在的直接掩蔽音在 周边听觉系统都很好理解，这是不是更多的情况 涉及空间、时间和交叉频率的复杂形式的掩蔽 可能是中心起源并可能降低语音质量的互动 在存在竞争声音的情况下的接收。我们建议调查 周围和中枢神经机制掩盖的语言和 其他声学刺激通过测量掩蔽阈值的单一单位在 使用相同的刺激， 就像心理物理实验一样。 具体目标1是测试陷波噪声的生理有效性 精神病学家用来从掩蔽中估计听觉滤波器形状的方法 人类的数据。 目的2是研究前向掩蔽的神经基础，这是最小的 在AN中，但是在IC中，可以与心理物理前向掩蔽相当。 目的3是寻找从掩蔽中释放的神经相关因素， 当附加的声音以与声音相同的频率被调幅时， 屏蔽器被引入。这种“共调节掩蔽释放”被认为有助于 在存在干扰声音的情况下的语音接收， 在宽频率范围内的调制模式。 目的4是确定简单刺激的神经掩蔽措施是否可以 用于预测语音中特定语音对比的掩蔽。这 研究解决了听觉理论中的基本问题，如神经 听觉分组的机制，外周和中枢因素在 掩蔽和用于信号检测的神经代码。可能导致 更好地理解为什么听障和老年听众有更大的 比正常人更难理解竞争声音中的言语 助听器的种类和作用 （耳蜗和脑干）植入物，在嘈杂的环境中表现更好。

DESCRIPTION: (Adapted from the Investigator's Abstract) Most speech conversations occur in the presence of competing sounds such as other voices or environmental noise. Hearing-impaired people often complain of difficulties understanding speech in noise backgrounds even if they do well in quiet. While physiological mechanisms underlying the direct masking of tones in the peripheral auditory system are well understood, this is not the case for more complex forms of masking involving spatial, temporal and cross-frequency interactions that are likely to be of central origin, and may degrade speech reception in the presence of competing sounds. We propose to investigate peripheral and central neural mechanisms underlying the masking of speech and other acoustic stimuli by measuring masked thresholds of single units in the auditory-nerve (AN) and inferior colliculus (IC) using the same stimuli and detection measures as in psychophysical experiments. Specific Aim 1 is to test the physiological validity of the notched-noise method used by psychophysicists to estimate auditory filter shapes from masking data in humans. Aim 2 is to investigate the neural basis for forward masking, which is minimal in the AN but, in the IC may be comparable to psychophysical forward masking. Aim 3 is to find neural correlates of the release from masking which occurs when additional sounds that are amplitude-modulated at the same frequency as a masker are introduced. Such "comodulation masking release" is thought to aid speech reception in the presence of interfering sounds that share a common pattern of modulation over broad frequency ranges. Aim 4 is to determine whether measures of neural masking for simple stimuli can be used to predict the masking of specific phonetic contrasts in speech. This research addresses fundamental issues in auditory theory such as neural mechanisms of auditory grouping, the roles of peripheral and central factors in masking, and the neural codes used for signal detection. It may lead to a better understanding of why hearing-impaired and elderly listeners have greater difficulties understanding speech among competing sounds than do normal listeners, and may help develop new kinds of hearing aids and auditory (cochlear and brainstem) implants that perform better in noisy environments.