Vanderbilt University Medical Center.
Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, California, USA.
Ear Hear. 2019 Sep/Oct;40(5):1127-1139. doi: 10.1097/AUD.0000000000000690.
Cochlear implant (CI) users suffer from a range of speech impairments, such as stuttering and vocal control of pitch and intensity. Though little research has focused on the role of auditory feedback in the speech of CI users, these speech impairments could be due in part to limited access to low-frequency cues inherent in CI-mediated listening. Phantom electrode stimulation (PES) represents a novel application of current steering that extends access to low frequencies for CI recipients. It is important to note that PES transmits frequencies below 300 Hz, whereas Baseline does not. The objective of this study was to explore the effects of PES on multiple frequency-related characteristics of voice production.
Eight postlingually deafened, adult Advanced Bionics CI users underwent a series of vocal production tests including Tone Repetition, Vowel Sound Production, Passage Reading, and Picture Description. Participants completed all of these tests twice: once with PES and once using their program used for everyday listening (Baseline). An additional test, Automatic Modulation, was included to measure acute effects of PES and was completed only once. This test involved switching between PES and Baseline at specific time intervals in real time as participants read a series of short sentences. Finally, a subjective Vocal Effort measurement was also included.
In Tone Repetition, the fundamental frequencies (F0) of tones produced using PES and the size of musical intervals produced using PES were significantly more accurate (closer to the target) compared with Baseline in specific gender, target tone range, and target tone type testing conditions. In the Vowel Sound Production task, vowel formant profiles produced using PES were closer to that of the general population compared with those produced using Baseline. The Passage Reading and Picture Description task results suggest that PES reduces measures of pitch variability (F0 standard deviation and range) in natural speech production. No significant results were found in comparisons of PES and Baseline in the Automatic Modulation task nor in the Vocal Effort task.
The findings of this study suggest that usage of PES increases accuracy of pitch matching in repeated sung tones and frequency intervals, possibly due to more accurate F0 representation. The results also suggest that PES partially normalizes the vowel formant profiles of select vowel sounds. PES seems to decrease pitch variability of natural speech and appears to have limited acute effects on natural speech production, though this finding may be due in part to paradigm limitations. On average, subjective ratings of vocal effort were unaffected by the usage of PES versus Baseline.
人工耳蜗（CI）使用者存在一系列言语障碍，如口吃和音高、强度的声音控制。尽管很少有研究关注听觉反馈在 CI 用户言语中的作用，但这些言语障碍部分可能是由于 CI 介导的听力中固有低频线索的获取受限所致。幻像电极刺激（PES）代表了一种电流转向的新应用，它为 CI 受者扩展了对低频的获取。值得注意的是，PES 传输低于 300 Hz 的频率，而基线则不传输。本研究的目的是探讨 PES 对声音产生的多个与频率相关的特征的影响。
八名后天失聪的成人先进仿生学 CI 用户接受了一系列声音产生测试，包括音高重复、元音发音、段落阅读和图片描述。参与者两次完成所有这些测试：一次使用 PES，一次使用他们日常听力的程序（基线）。还包括一项自动调制测试，以测量 PES 的急性影响，仅完成一次。该测试涉及参与者在阅读一系列短句子时实时在 PES 和基线之间切换特定时间间隔。最后，还包括一项主观声音努力测量。
在音高重复中，与基线相比，使用 PES 产生的音调的基频（F0）和使用 PES 产生的音乐间隔的大小在特定性别、目标音调范围和目标音调类型测试条件下更准确（更接近目标）。在元音发音任务中，与使用基线相比，使用 PES 产生的元音共鸣特征更接近一般人群。段落阅读和图片描述任务的结果表明，在自然言语产生中，PES 降低了音高变化（F0 标准差和范围）的测量值。在自动调制任务和声音努力任务中，在 PES 和基线的比较中没有发现显著结果。
本研究结果表明，使用 PES 增加了重复 sung 音调和频率间隔中音调匹配的准确性，可能是由于更准确的 F0 表示。结果还表明，PES 部分使选定元音的元音共鸣特征正常化。PES 似乎降低了自然言语的音高变化，并且似乎对自然言语产生的急性影响有限，尽管这一发现可能部分归因于范式限制。平均而言，PES 与基线相比，声音努力的主观评分不受影响。
