Neuroscience Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Department of Psychology, Harvard University, Cambridge, MA, USA.
Ear Hear. 2024;45(2):337-350. doi: 10.1097/AUD.0000000000001432. Epub 2023 Sep 11.
Although cochlear implants (CIs) facilitate spoken language acquisition, many CI listeners experience difficulty learning new words. Studies have shown that highly variable stimulus input and audiovisual cues improve speech perception in CI listeners. However, less is known whether these two factors improve perception in a word learning context. Furthermore, few studies have examined how CI listeners direct their gaze to efficiently capture visual information available on a talker's face. The purpose of this study was two-fold: (1) to examine whether talker variability could improve word learning in CI listeners and (2) to examine how CI listeners direct their gaze while viewing a talker speak.
Eighteen adults with CIs and 10 adults with normal hearing (NH) learned eight novel word-object pairs spoken by a single talker or six different talkers (multiple talkers). The word learning task comprised of nonsense words following the phonotactic rules of English. Learning was probed using a novel talker in a two-alternative forced-choice eye gaze task. Learners' eye movements to the mouth and the target object (accuracy) were tracked over time.
Both groups performed near ceiling during the test phase, regardless of whether they learned from the same talker or different talkers. However, compared to listeners with NH, CI listeners directed their gaze significantly more to the talker's mouth while learning the words.
Unlike NH listeners who can successfully learn words without focusing on the talker's mouth, CI listeners tended to direct their gaze to the talker's mouth, which may facilitate learning. This finding is consistent with the hypothesis that CI listeners use a visual processing strategy that efficiently captures redundant audiovisual speech cues available at the mouth. Due to ceiling effects, however, it is unclear whether talker variability facilitated word learning for adult CI listeners, an issue that should be addressed in future work using more difficult listening conditions.
尽管人工耳蜗（CI）有助于获得口语，但许多 CI 使用者在学习新单词方面仍存在困难。研究表明，高度变化的刺激输入和视听线索可以改善 CI 使用者的语音感知。然而，对于这两个因素是否可以改善单词学习的感知，了解较少。此外，很少有研究探讨 CI 使用者如何注视以有效地获取说话者面部上可用的视觉信息。本研究的目的有两个：（1）检验说话者变化是否可以改善 CI 使用者的单词学习；（2）检验 CI 使用者在观看说话者说话时如何注视。
18 名 CI 使用者和 10 名正常听力（NH）成人学习由单个说话者或六个不同说话者（多个说话者）说出的八个新单词-物体对。单词学习任务包括符合英语语音规则的无意义单词。使用新说话者在二选一强制选择眼动任务中探查学习情况。学习者的眼动追踪随时间跟踪到嘴和目标对象的准确度）。
无论他们是从同一个说话者还是不同的说话者学习，两组在测试阶段的表现都接近上限。但是，与 NH 听众相比，CI 听众在学习单词时更倾向于注视说话者的嘴。
与无需关注说话者的嘴就能成功学习单词的 NH 听众不同，CI 听众倾向于注视说话者的嘴，这可能有助于学习。这一发现与 CI 听众使用一种视觉处理策略的假设一致，该策略可以有效地捕获嘴巴处可用的冗余视听语音线索。但是，由于上限效应，尚不清楚说话者的变化是否有助于成年 CI 使用者的单词学习，这是未来使用更困难的听力条件的工作中应解决的问题。
