Eisenberg Laurie S, Martinez Amy Schaefer, Holowecky Suzanne R, Pogorelsky Stephanie
House Ear Institute, Los Angeles, California 90057, USA.
Ear Hear. 2002 Oct;23(5):450-62. doi: 10.1097/00003446-200210000-00007.
The purpose of this study was to investigate the combined lexical effects of word frequency and neighborhood density (acoustic-phonetic similarity) on the recognition of words spoken in isolation and words spoken in sentences for children with normal hearing and children with cochlear implants.
Lexically controlled sentences were created from a subset of words obtained from the spoken vocabulary of children between the ages of 3 and 5 yr. Two sentence lists were generated, applying the definitions and procedures of Kirk, Pisoni, and Osberger (1995) in accordance with the Neighborhood Activation Model ( Luce, 1986; Luce & Pisoni, 1998). One list was composed of lexically "easy" words (those high in frequency of occurrence but phonemically dissimilar to other words) and the other list was composed of lexically "hard" words (those low in frequency of occurrence but phonemically similar to other words). Each list consisted of five practice and 20 test sentences that were syntactically correct but semantically neutral (low in predictability). Three key words were used in constructing each of the 5- to 7-word sentences, resulting in 15 practice and 60 key words per test list. In the first of three experiments, 48 normal-hearing children between the ages of 5 and 12 yr were asked to repeat the words and sentences at one of six presentation levels to establish performance-intensity functions. In the second experiment, 12 normal-hearing children between the ages of 5 and 14 yr repeated the words and sentences under spectrally degraded conditions. Twelve children with cochlear implants ages 5 to 14 yr repeated the unprocessed stimuli in a third experiment.
The lexically easy stimuli were recognized with greater accuracy than the lexically hard stimuli for the children tested in all three experiments. Sentence scores were significantly higher than word scores for the normal-hearing children (Experiments 1 and 2) and nine high-performing children with cochlear implants (Experiment 3). Word scores were higher than sentence scores for the three low-performing children with cochlear implants. There was a statistically significant relationship between chronological age and sentence score for the normal-hearing children listening under spectrally degraded conditions. For the children with cochlear implants, the relationship between language quotient and sentence and word scores was statistically significant.
Sensitivity to the combined lexical properties of word frequency and neighborhood density was evident both for words and sentences. Lexically easy stimuli were recognized with greater accuracy than lexically hard stimuli across groups, affirming the robustness of this effect and verifying that words were being organized in relation to the frequency and acoustic-phonetic properties of other words. Syntactic context facilitated word recognition for the children with normal hearing and the high-performing implant group. The three low-performing children with cochlear implants recognized words more accurately than sentences, reflecting limitations in linguistic and cognitive capacity.
本研究旨在调查词频和邻域密度（语音相似性）对听力正常儿童和人工耳蜗植入儿童孤立单词及句子中单词识别的综合词汇效应。
从3至5岁儿童口语词汇的一个子集中创建词汇控制句子。根据邻域激活模型（Luce，1986；Luce & Pisoni，1998），应用Kirk、Pisoni和Osberger（1995）的定义和程序生成两个句子列表。一个列表由词汇“简单”的单词组成（出现频率高但语音与其他单词不同），另一个列表由词汇“困难”的单词组成（出现频率低但语音与其他单词相似）。每个列表包含五个练习句子和20个测试句子，这些句子在语法上正确但语义中立（可预测性低）。构建每个5至7个单词的句子时使用了三个关键词，每个测试列表产生15个练习关键词和60个关键词。在三个实验的第一个实验中，48名5至12岁听力正常的儿童被要求在六个呈现水平之一重复单词和句子，以建立表现强度函数。在第二个实验中，12名5至14岁听力正常的儿童在频谱退化条件下重复单词和句子。12名5至14岁的人工耳蜗植入儿童在第三个实验中重复未处理的刺激。
在所有三个实验中测试的儿童中，词汇简单的刺激比词汇困难的刺激识别准确率更高。对于听力正常的儿童（实验1和2）以及九名表现良好的人工耳蜗植入儿童（实验3），句子得分显著高于单词得分。三名表现不佳的人工耳蜗植入儿童的单词得分高于句子得分。在频谱退化条件下聆听的听力正常儿童的实际年龄与句子得分之间存在统计学上的显著关系。对于人工耳蜗植入儿童，语言商数与句子和单词得分之间的关系具有统计学意义。
对于单词和句子，对词频和邻域密度的综合词汇属性的敏感性都很明显。在各个组中，词汇简单的刺激比词汇困难的刺激识别准确率更高，这证实了这种效应的稳健性，并验证了单词是根据其他单词的频率和语音属性进行组织的。句法语境促进了听力正常儿童和表现良好的植入组儿童的单词识别。三名表现不佳的人工耳蜗植入儿童识别单词比识别句子更准确，这反映了语言和认知能力的局限性。
