Neural encoding of speech envelopes during development: A frequency-specific investigation

项目摘要 在安静和有噪音的情况下理解语音的一个重要的基于时间的提示是语音的周期性 以基频(F0)发声。儿童使用f0速率信息进行语音理解的能力- ING取决于他们的听觉系统在每个频率区域提取这些信息的能力。一种能力 提取这样的信息可能是在fl中被神经通路的发展所依赖的人工耳蜗位置特殊fic 听觉加工倾向于在支配耳蜗基的通路中更早地发展。F0编码- 可以使用包络跟随响应(EFRS)来评估ING-一种基于脑电的方法， fl检测神经活动的相位锁定在周期f0包络内。然而，人们对这种频率知之甚少- 由于主要使用宽带元音来引发EFR，所以fic发展了f0编码。对这件事 最后，我们的目标是系统地评估f0编码的频率谱fic的发展时程。 建议的研究将使用新的频带限制言语刺激来研究儿童的发育时间进程。 F0编码起始于对应于低、中、高频的不同耳蜗区。除了……之外 使用频率谱fic方法，将作为(I)f0速率的函数来评估f0编码-该参数 说话者年龄和性别的变化，(Ii)信噪比下降--这是一个模拟挑战的参数 听力条件，特别是对儿童来说，和(Iii)刺激的行为相关性-一个参数，可以 消除日常听力体验的影响。感兴趣的两个年龄段的未成熟儿童 对f0频率包络周期的感知是0.3-1年和5-8年，因为它们与成熟的耳蜗相一致，并且 分别检测耳蜗肌和脑干功能。用于在存在时对f0编码进行严格的成人-儿童比较 对于年龄相关的耳朵和头部大小，这种方法将需要：(I)在每个测试耳朵中进行刺激校准，以使其均衡 所有测试耳朵的刺激水平，(Ii)使用相位一致性--独立于 绝对反应强度和潜伏期-作为成熟度指标，以及(Iii)刺激的组间比较- 导致的变化，而不是原始的EFR措施。研究结果将揭示低频的f0编码是否是最后一次编码 以实现成人一样的处理，如果这样的发展轨迹是特定的fic到语言。 这项拟议的研究对患有耳蜗性听力损失的儿童具有重要意义，他们可能会经历 频率谱fic异常f0编码作为听力损失程度的函数。年龄、频率、速率、信号- 从建议的工作中开发的f0编码的信噪比和刺激特性fic将提高我们的能力 检测和评估由于耳蜗性听力损失和/或信号引起的f0编码异常的性质和程度 在助听器等设备中进行处理。EFRs的使用也将使儿童能够评估f0编码 年轻人参加行为听力测试，进而提供机会通知干预措施的变化 比行为听力测试更早。

Project Summary An important time-based cue for understanding speech in quiet and in the presence of noise is the periodicity in voicing at the fundamental frequency (f0). The ability of children to use f0-rate information for speech understand- ing depends on how well their auditory system extracts this information in each frequency region. The ability to extract such information could be influenced by the cochlear-place-specific development of neural pathways and the tendency for auditory processing to develop earlier in pathways innervating the cochlear base. f0 encod- ing can be evaluated using envelope following response (EFRs)—an electroencephalogram-based method that reflects neural activity phase-locked to the periodic f0 envelope. However, little is known about the frequency- specific development of f0 encoding because of the predominant use of broadband vowels to elicit EFRs. To this end, our goal is to systematically evaluate the frequency-specific developmental time course of f0 encoding. The proposed studies will use novel band-limited speech stimuli to investigate the developmental time course of f0 encoding initiated in different cochlear regions corresponding to low, mid and high frequencies. In addition to using a frequency-specific approach, f0 encoding will be assessed as a function of (i) f0 rate—a parameter that changes by talker age and gender, (ii) decreasing signal-to-noise ratio—a parameter that simulates challenging listening conditions especially for children, and (iii) behavioral relevance of the stimulus—a parameter that can disambiguate the impact of everyday listening experience. The two pediatric age groups of interest with immature perception of f0-rate envelope periodicity are, 0.3-1 years and 5-8 years, as they align with mature cochlear, and cochlear and brainstem function, respectively. For rigorous adult-child comparisons of f0 encoding in the presence of age-dependent ear and head sizes, the approach will entail: (i) stimulus calibration in each test ear to equalize stimulus level across all test ears, (ii) use of phase coherence—a normalized response measure independent of absolute response strength and latency—as the maturity metric, and (iii) between-group comparisons of stimulus- induced changes rather than raw EFR measures. Findings will reveal if f0 encoding at low frequencies is the last to achieve adult-like processing and if such a developmental trajectory is specific to speech. The proposed research has important implications for children with cochlear hearing loss who may experience frequency-specific abnormal f0 encoding as a function of hearing loss degree. The age-, frequency-, rate-, signal- to-noise ratio-, and stimulus-specific development of f0 encoding from the proposed work will advance our ability to detect and assess the nature and extent of abnormal f0 encoding due to cochlear hearing loss and/or signal processing in devices like hearing aids. The use of EFRs will enable assessment of f0 encoding in children too young to participate in behavioral hearing tests and in turn, offer the opportunity to inform changes in intervention earlier than behavioral hearing tests can.