Sommers Mitchell S, Tye-Murray Nancy, Spehar Brent
Department of Psychology, Washington University, St. Louis, Missouri 63130, USA.
Ear Hear. 2005 Jun;26(3):263-75. doi: 10.1097/00003446-200506000-00003.
The purpose of the present study was to examine the effects of age on the ability to benefit from combining auditory and visual speech information, relative to listening or speechreading alone. In addition, the study was designed to compare visual enhancement (VE) and auditory enhancement (AE) for consonants, words, and sentences in older and younger adults.
Forty-four older adults and 38 younger adults with clinically normal thresholds for frequencies of 4 kHz and below were asked to identify vowel-consonant-vowels (VCVs), words in a carrier phrase, and semantically meaningful sentences in auditory-only (A), visual-only (V), and auditory-visual (AV) conditions. All stimuli were presented in a background of 20-talker babble, and signal-to-babble ratios were set individually for each participant and each stimulus type to produce approximately 50% correct in the A condition.
For all three types of stimuli, older and younger adults obtained similar scores for the A condition, indicating that the procedure for individually adjusting signal-to-babble ratios was successful at equating A scores for the two age groups. Older adults, however, had significantly poorer performance than younger adults in the AV and V modalities. Analyses of both AE and VE indicated no age differences in the ability to benefit from combining auditory and visual speech signals after controlling for age differences in the V condition. Correlations between scores for the three types of stimuli (consonants, words, and sentences) indicated moderate correlations in the V condition but small correlations for AV, AE, and VE.
Overall, the findings suggest that the poorer performance of older adults in the AV condition was a result of reduced speechreading abilities rather than a consequence of impaired integration capacities. The pattern of correlations across the three stimulus types indicates some overlap in the mechanisms mediating AV perception of words and sentences and that these mechanisms are largely independent from those used for AV perception of consonants.
本研究的目的是检验年龄对从听觉和视觉言语信息组合中获益的能力的影响，相较于单独听或唇读。此外，该研究旨在比较老年人和年轻人在辅音、单词和句子方面的视觉增强（VE）和听觉增强（AE）。
44名老年人和38名4kHz及以下频率临床阈值正常的年轻人被要求在仅听觉（A）、仅视觉（V）和听觉 - 视觉（AV）条件下识别元音 - 辅音 - 元音（VCV）、载体短语中的单词以及语义有意义的句子。所有刺激均呈现于20人嘈杂声背景中，并且针对每个参与者和每种刺激类型分别设置信噪比，以使A条件下的正确率约为50%。
对于所有三种类型的刺激，老年人和年轻人在A条件下获得了相似的分数，这表明单独调整信噪比的程序成功地使两个年龄组的A分数相等。然而，老年人在AV和V模式下的表现明显比年轻人差。对AE和VE的分析表明，在控制了V条件下的年龄差异后，从听觉和视觉言语信号组合中获益的能力没有年龄差异。三种类型刺激（辅音、单词和句子）的分数之间的相关性表明在V条件下相关性中等，但在AV、AE和VE条件下相关性较小。
总体而言，研究结果表明老年人在AV条件下表现较差是唇读能力下降的结果，而非整合能力受损的后果。三种刺激类型之间的相关模式表明，介导单词和句子AV感知的机制存在一些重叠，并且这些机制在很大程度上独立于用于辅音AV感知的机制。
