Sommers M S, Kirk K I, Pisoni D B
Department of Psychology, Washington University, St Louis, Missouri 63130, USA.
Ear Hear. 1997 Apr;18(2):89-99. doi: 10.1097/00003446-199704000-00001.
The purpose of the present studies was to assess the validity of using closed-set response formats to measure two cognitive processes essential for recognizing spoken words---perceptual normalization (the ability to accommodate acoustic-phonetic variability) and lexical discrimination (the ability to isolate words in the mental lexicon). In addition, the experiments were designed to examine the effects of response format on evaluation of these two abilities in normal-hearing (NH), noise-masked normal-hearing (NMNH), and cochlear implant (CI) subject populations.
The speech recognition performance of NH, NMNH, and CI listeners was measured using both open- and closed-set response formats under a number of experimental conditions. To assess talker normalization abilities, identification scores for words produced by a single talker were compared with recognition performance for items produced by multiple talkers. To examine lexical discrimination, performance for words that are phonetically similar to many other words (hard words) was compared with scores for items with few phonetically similar competitors (easy words).
Open-set word identification for all subjects was significantly poorer when stimuli were produced in lists with multiple talkers compared with conditions in which all of the words were spoken by a single talker. Open-set word recognition also was better for lexically easy compared with lexically hard words. Closed-set tests, in contrast, failed to reveal the effects of either talker variability or lexical difficulty even when the response alternatives provided were systematically selected to maximize confusability with target items.
These findings suggest that, although closed-set tests may provide important information for clinical assessment of speech perception, they may not adequately evaluate a number of cognitive processes that are necessary for recognizing spoken words. The parallel results obtained across all subject groups indicate that NH, NMNH, and CI listeners engage similar perceptual operations to identify spoken words. Implications of these findings for the design of new test batteries that can provide comprehensive evaluations of the individual capacities needed for processing spoken language are discussed.
本研究的目的是评估使用封闭式反应格式来测量识别口语单词所必需的两个认知过程——感知归一化（适应声学语音变异性的能力）和词汇辨别（在心理词典中分离单词的能力）的有效性。此外，这些实验旨在研究反应格式对正常听力（NH）、噪声掩蔽正常听力（NMNH）和人工耳蜗（CI）受试者群体中这两种能力评估的影响。
在多种实验条件下，使用开放式和封闭式反应格式测量NH、NMNH和CI听众的语音识别表现。为了评估说话者归一化能力，将单个说话者说出的单词的识别分数与多个说话者说出的项目的识别表现进行比较。为了检验词汇辨别能力，将与许多其他单词在语音上相似的单词（难词）的表现与语音相似竞争者较少的项目（易词）的分数进行比较。
与所有单词由单个说话者说出的情况相比，当刺激以多个说话者的列表形式呈现时，所有受试者的开放式单词识别明显更差。与词汇难的单词相比，词汇易的单词的开放式单词识别也更好。相比之下，即使所提供的反应选项经过系统选择以最大程度地增加与目标项目的混淆性，封闭式测试也未能揭示说话者变异性或词汇难度的影响。
这些发现表明，尽管封闭式测试可能为语音感知的临床评估提供重要信息，但它们可能无法充分评估识别口语单词所需的一些认知过程。在所有受试者组中获得的平行结果表明，NH、NMNH和CI听众在识别口语单词时采用了相似的感知操作。讨论了这些发现对设计能够全面评估处理口语所需个体能力的新测试组的意义。
