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

描述（由申请人提供）：言语感知对听者提出了两个难题。首先，声学信号是可变的并且依赖于上下文，使得音素识别困难。本研究旨在了解听者如何解决这两个问题，以及这些问题之间的关系，并以此来了解两组受损的听者：语言障碍（LI）听者和使用耳蜗植入物（CI）的听者。项目1询问听众如何补偿由于说话者和语音背景的变化，以及补偿如何与听众在单词识别过程中暂时考虑的候选单词之间的竞争相互作用。它采用事件相关电位来评估补偿是否发生在听觉编码水平或随后的分类过程中。它还使用眼动追踪来检查词汇竞争对手的每时每刻的激活（听众并行考虑多个单词的强烈程度），询问声学线索和补偿过程何时影响词汇处理。最后，它检查CI用户的困难，确定说话者可能会抑制他们的补偿能力。这可能导致更好的处理策略、设备配置和治疗。项目2研究了听者如何在一个词中表示信息的顺序（例如，他们如何区分anadromes像猫和大头钉）。大多数模型使用音素的序列顺序来排除anadrome竞争对手。然而，最近的数据表明，听众并没有完全排除anadrome，这表明秩序没有明确表示。项目2使用眼动跟踪和视觉世界范式与已知的单词和小的人工语言，以确定听众是否使用细粒度的声学细节（音素在音节起始和结尾位置的发音差异）作为顺序的代理。它还研究了听众与LI，谁可能有赤字与细粒度的听觉细节和串行顺序;和CI用户谁缺乏访问细粒度的频谱细节。这将评估强调听觉或顺序缺陷作为LI来源的语言障碍理论。它还将帮助我们了解CI用户之间结果的变化，并进一步完善我们对CI必须传输的声学信息的理解。项目3询问在单词识别过程中词汇竞争者保持活跃的时间。先前的研究发现，听力障碍的听众在单词识别过程中不会完全抑制词汇竞争对手。项目3开发了一个眼动追踪范式，以评估竞争对手活跃的时间，并询问是什么机制维持它，检查单词之间的抑制，回声记忆和语音短期记忆。它测试了听力障碍者和交际障碍者，以确定这种高度竞争的后果，它与其他语言过程的关系，以及障碍的位置。在所有三个项目中，该提案旨在更好地描述正常听众的言语感知的基本机制，目的是使用这种表征来更好地理解受损听众所面临的独特问题。

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.