1Boys Town National Research Hospital, Omaha, Nebraska, USA; and 2Communication Sciences and Disorders, University of Utah, Salt Lake City, Utah, USA.
Ear Hear. 2017 Sep/Oct;38(5):e292-e304. doi: 10.1097/AUD.0000000000000428.
This study investigated the possible impact of simulated hearing loss on speech perception in Spanish-English bilingual children. To avoid confound between individual differences in hearing-loss configuration and linguistic experience, threshold-elevating noise simulating a mild-to-moderate sloping hearing loss was used with normal-hearing listeners. The hypotheses were that: (1) bilingual children can perform similarly to English-speaking monolingual peers in quiet; (2) for both bilingual and monolingual children, noise and simulated hearing loss would have detrimental impacts consistent with their acoustic characteristics (i.e., consonants with high-frequency cues remain highly intelligible in speech-shaped noise, but suffer from simulated hearing loss more than other consonants); (3) differences in phonology and acquisition order between Spanish and English would have additional negative influence on bilingual children's recognition of some English consonants.
Listeners were 11 English-dominant, Spanish-English bilingual children (6 to 12 years old) and 12 English-speaking, monolingual age peers. All had normal hearing and age-appropriate nonverbal intelligence and expressive English vocabulary. Listeners performed a listen-and-repeat speech perception task. Targets were 13 American English consonants embedded in vowel-consonant-vowel (VCV) syllables. VCVs were presented in quiet and in speech-shaped noise at signal-to-noise ratios (SNRs) of -5, 0, 5 dB (normal-hearing condition). For the simulated hearing-loss condition, threshold-elevating noise modeling a mild-to-moderate sloping sensorineural hearing loss profile was added to the normal-hearing stimuli for 0, 5 dB SNR, and quiet. Responses were scored for consonant correct. Individual listeners' performance was summarized for average across 13 consonants (overall) and for individual consonants.
Groups were compared for the effects of background noise and simulated hearing loss. As predicted, group performed similarly in quiet. The simulated hearing loss had a considerable detrimental impact on both groups, even in the absence of speech-shaped noise. Contrary to our prediction, no group difference was observed at any SNR in either condition. However, although nonsignificant, the greater within-group variance for the bilingual children in the normal-hearing condition indicated a wider "normal" range than for the monolingual children. Interestingly, although it did not contribute to the group difference, bilingual children's overall consonant recognition in both conditions improved with age, whereas such a developmental trend for monolingual children was observed only in the simulated hearing-loss condition, suggesting possible effects of experience. As for the recognition of individual consonants, the influence of background noise or simulated hearing loss was similar between groups and was consistent with the prediction based on their acoustic characteristics.
The results demonstrated that school-age, English-dominant, Spanish-English bilingual children can recognize English consonants in a background of speech-shaped noise with similar average accuracy as English-speaking monolingual age peers. The general impact of simulated hearing loss was also similar between bilingual and monolingual children. Thus, our hypothesis that bilingual children's English consonant recognition would suffer from background noise or simulated hearing loss more than the monolingual peers was rejected. However, the present results raise several issues that warrant further investigation, including the possible difference in the "normal" range for bilingual and monolingual children, influence of experience, impact of actual hearing loss on bilingual children, and stimulus quality.
本研究旨在探讨模拟听力损失对西班牙语-英语双语儿童言语感知的可能影响。为了避免听力损失配置和语言经验个体差异的混淆，使用模拟轻度至中度倾斜感音神经性听力损失的阈上噪声对正常听力的听众进行了测试。假设为：（1）双语儿童在安静环境中与以英语为母语的单语同龄人表现相似；（2）对于双语和单语儿童来说，噪声和模拟听力损失的影响与其声学特征一致（即，具有高频线索的辅音在语音噪声中仍保持高度可懂，但比其他辅音更易受模拟听力损失的影响）；（3）西班牙语和英语的语音和习得顺序的差异会对双语儿童识别某些英语辅音产生额外的负面影响。
参与者为 11 名以英语为主导的西班牙语-英语双语儿童（6 至 12 岁）和 12 名以英语为母语的单语年龄同龄人。所有参与者均具有正常听力和适合年龄的非言语智力和表达性英语词汇量。参与者进行了听和复述言语感知任务。目标是 13 个美国英语辅音，嵌入元音-辅音-元音（VCV）音节中。VCV 在信噪比（SNR）为-5、0、5 dB 的安静环境和语音噪声中呈现（正常听力条件）。对于模拟听力损失条件，在正常听力刺激中添加阈上噪声，模拟轻度至中度倾斜感音神经性听力损失特征，用于 0、5 dB SNR 和安静环境。响应以辅音正确得分。根据 13 个辅音的平均（整体）和个别辅音，对个别听众的表现进行了总结。
对背景噪声和模拟听力损失的影响进行了组间比较。正如预测的那样，两组在安静环境中的表现相似。模拟听力损失对两组都有相当大的不利影响，即使没有语音噪声也是如此。与我们的预测相反，在任何 SNR 下，在两种情况下都没有观察到组间差异。然而，尽管不显著，双语儿童在正常听力条件下的组内方差较大，表明正常范围较宽，而单语儿童的正常范围较窄。有趣的是，尽管双语儿童在两种情况下的整体辅音识别能力都随着年龄的增长而提高，但这并没有导致组间差异，而单语儿童只有在模拟听力损失条件下才观察到这种发展趋势，这表明经验可能有影响。至于对个别辅音的识别，背景噪声或模拟听力损失的影响在两组之间相似，与基于其声学特征的预测一致。
研究结果表明，学龄期以英语为主导的西班牙语-英语双语儿童可以在语音噪声背景下以与以英语为母语的单语年龄同龄人相似的平均准确度识别英语辅音。模拟听力损失的一般影响在双语和单语儿童之间也相似。因此，我们假设双语儿童的英语辅音识别能力会比单语同龄人更容易受到背景噪声或模拟听力损失的影响，这一假设被否定了。然而，目前的结果提出了一些需要进一步研究的问题，包括双语和单语儿童的“正常”范围差异、经验的影响、实际听力损失对双语儿童的影响以及刺激质量。
