Speech perception, acoustic variability and time: normal and impaired listeners

描述(申请人提供)：言语感知给听者带来了两个难题。首先，声学信号是可变的和上下文相关的，这使得音素识别变得困难。其次，它随着时间的推移而展开，在一个单词的早期，可能没有足够的信息来识别它。本研究旨在了解听者如何解决这两个问题，以及这些问题是如何相互关联的，并利用这一点来理解两组受损的听者：语言障碍听者(LI)和使用人工耳蜗的听者(CI)。项目1询问听话者如何补偿说话者和语音语境的变化，以及补偿如何与听话者在单词识别过程中瞬间考虑的候选单词之间展开的竞争相互作用。它使用事件相关电位来评估补偿是发生在听觉编码的水平上，还是发生在后来的分类过程中。它还使用眼球跟踪来检查词汇竞争对手的每时每刻的激活情况(收听者同时考虑多个单词的强度)，询问声音提示和补偿过程对词汇处理的影响。最后，它检查了CI用户，他们识别说话者的困难可能会抑制他们的补偿能力。这可能会带来更好的处理策略、设备配置和疗法。项目2考察了听者如何表示单词中信息的顺序(例如，他们如何区分CAT和Tack等前缀)。大多数型号使用音素的顺序，以排除与之竞争的音素。然而，最近的数据表明，听者并不完全排除顺序，这表明顺序并没有明确表示出来。项目2使用眼睛跟踪和视觉世界范式，通过熟知的单词和小型人工语言来确定听众是否使用细粒度的声学细节(音素在音节中的发音方式的差异-声母和词尾位置)作为顺序的代理。它还检查了LI的听众，他们可能在细粒度听觉细节和序列顺序方面都有缺陷；以及无法获得细粒度频谱细节的CI用户。这将评估语言障碍的理论，这些理论强调听觉或序列缺陷是李氏障碍的来源。它还将帮助我们了解CI用户之间结果的差异性，并进一步完善我们对CI必须传输哪些声学信息的理解。项目3询问词汇竞争者在单词识别过程中保持活跃的时间。先前的研究发现，在单词识别过程中，有李的听者并不完全抑制词汇竞争对手。项目3开发了一种眼球跟踪范式，以评估竞争对手活跃的时间，并询问是什么机制维持了这种状态，检查了单词之间的抑制、回声记忆和语音短期记忆。它对听者进行调查，以确定这种加剧的竞争的后果，它如何与其他语言过程相关，以及损害的根源。在所有三个项目中，这项建议旨在更好地描述正常听者的言语感知潜在机制，目的是利用这种描述来更好地理解受损听者面临的独特问题。

DESCRIPTION (provided by applicant): Speech perception poses two difficult problems for listeners. First, the acoustic signal is variable and context dependent, making phoneme identification difficult. Second, it unfolds over time and at early points in a word there may not e sufficient information to identify it. This research aims to understand how listeners solve both problems, how these problems relate to each other, and to use this to understand two groups of impaired listeners: listeners with Language Impairment (LI) and listeners who use Cochlear Implants (CIs). Project 1 asks how listeners compensate for variation due to talker and phonetic context, and how compensation interacts with unfolding competition between candidate words that listeners momentarily consider during word recognition. It employs event related potentials to assess whether compensation occurs at the level of auditory encoding or during later categorical processes. It also uses eye-tracking to examine moment-by-moment activation of lexical competitors (how strongly listeners consider multiple words in parallel), asking when acoustic cues and compensation processes impact lexical processing. Finally, it examines CI users whose difficulty identifying talkers may inhibit their compensation abilities. This may lead to better processing strategies, device configurations and therapies. Project 2 examines how listeners represent the order of information in a word (e.g., how they distinguish anadromes like cat and tack). Most models use the serial order of the phonemes to exclude anadrome competitors. However, recent data indicate that listeners do not completely rule out anadromes, suggesting that order is not explicitly represented. Project 2 uses eye-tracking and visual world paradigm with known words and small artificial languages to determine whether listeners use fine-grained acoustic detail (differences in how a phoneme is pronounced in syllable-initial and final positions) as a proxy for order. It also examines listeners with LI, who may have deficits with both fine-grained auditory detail and serial order; and CI users who lack access to fine-grained spectral detail. This will assess theories of language impairment that emphasis auditory or sequencing deficits as the source of LI. It will also help us understand the variability in outcomes among CI users and further refine our understanding of what acoustic information must be transmitted by the CI. Project 3 asks how long lexical competitors remain active during word recognition. The prior grant discovered that listeners with LI do not fully suppress lexical competitors during word recognition. Project 3 develops an eye-tracking paradigm to assess how long competitors are active, and to ask what mechanisms maintain it, examining inhibition between words, echoic memory and phonological short-term memory. It ex- amines listeners with LI and CI users to determine the consequences of this heightened competition, how it relates to other language processes, and the locus of the impairment. Across all three projects, this proposal aims to better characterize the underlying mechanisms of speech perception in normal listeners with the goal of using this characterization to better understand the unique problems faced by impaired listeners.