University of Southampton Auditory Implant Service, University of Southampton, University Road, Southampton, SO17 1BJ, UK.
Institute of Sound and Vibration Research, University of Southampton, University Road, Southampton, SO17 1BJ, UK.
Sci Rep. 2024 Feb 28;14(1):4889. doi: 10.1038/s41598-024-55429-3.
Haptic hearing aids, which provide speech information through tactile stimulation, could substantially improve outcomes for both cochlear implant users and for those unable to access cochlear implants. Recent advances in wide-band haptic actuator technology have made new audio-to-tactile conversion strategies viable for wearable devices. One such strategy filters the audio into eight frequency bands, which are evenly distributed across the speech frequency range. The amplitude envelopes from the eight bands modulate the amplitudes of eight low-frequency tones, which are delivered through vibration to a single site on the wrist. This tactile vocoder strategy effectively transfers some phonemic information, but vowels and obstruent consonants are poorly portrayed. In 20 participants with normal touch perception, we tested (1) whether focusing the audio filters of the tactile vocoder more densely around the first and second formant frequencies improved tactile vowel discrimination, and (2) whether focusing filters at mid-to-high frequencies improved obstruent consonant discrimination. The obstruent-focused approach was found to be ineffective. However, the formant-focused approach improved vowel discrimination by 8%, without changing overall consonant discrimination. The formant-focused tactile vocoder strategy, which can readily be implemented in real time on a compact device, could substantially improve speech perception for haptic hearing aid users.
触觉助听器通过触觉刺激提供言语信息，可以大大改善人工耳蜗植入用户和无法接受人工耳蜗植入用户的效果。宽带触觉致动器技术的最新进展使得新的音频到触觉转换策略对于可穿戴设备变得可行。该策略之一是将音频过滤成八个频带，这些频带均匀分布在语音频率范围内。来自八个频带的幅度包络调制八个低频音的幅度，这些低频音通过振动传递到手腕上的单个位置。这种触觉声码器策略有效地传递了一些音位信息，但元音和塞音辅音的表现很差。在 20 名具有正常触觉感知的参与者中，我们测试了（1）是否通过将触觉声码器的音频滤波器更密集地聚焦在第一和第二共振峰频率周围来提高触觉元音辨别力，以及（2）是否通过聚焦在中高频来提高塞音辅音辨别力。发现阻塞音聚焦方法无效。然而，共振峰聚焦方法将元音辨别能力提高了 8%，而不会改变整体辅音辨别能力。该共振峰聚焦触觉声码器策略可以在紧凑的设备上实时实现，从而可以大大改善触觉助听器用户的语音感知。
