聽力輔具的語音處理機製作

Abstract

本論文之目的旨在結合正弦模型分析與語音轉換技術，並配合聲響心理學的相關知識，開發一種適合感音性聽障患者使用的語音處理機。主要是考慮到感音性聽障者內耳的耳蝸或神經組織有所缺損，導致其可聽閾值上升且音域頻寬縮減。除了需要一般助聽器所提供音量放大功能，還必須克服聽障者動態聽力範圍異常擠壓的困擾，才能有效改善其殘餘聽力以處理語音訊息。問題是若只單純地在語音時域或頻域上進行轉換處理並不可行，因為所衍生的頻移失真現象將嚴重扭曲原因的清晰寓意。有鑑於此，我們將先針對語音訊號作正弦模型分析，取得其正弦分量之頻率、相位與振幅的最佳組合。為了有效改善聽障者的語音理解能力，我們將依據其聽力動態範圍設計正弦振幅調整機制，以達成音域補償之目的。並加入語音轉換功能，使其能做不同音域頻寬播音而仍能保持其自然流利。語音合成部分，則考慮到音框與音框間的平滑處理，以解決相鄰音框間不連續現象。

Approximately 7.5 percent of the population has some degree of hearing loss, but only 15 percent of them are actually using hearing aids. Of the two major types of hearing loss, conductive and sensorineural, only the former can be adequately compensated using normally available hearing aids. This motivates our research into trying to devise an aid that properly deals with the restricted bandwidth and reduced dynamic range present in sensorineural hearing impaired. The strategy applied here is based on a sinusoidal model, in which speech waveforms are represented as the sum of sinusoids with specific frequencies, amplitudes, and phases. The motivation for this representation is two-fold. First, frequency-scale modification can easily be applied on sinusoidal parameters to place speech in a desired bandwidth as an aid to the hearing impaired. Secondly, compression of sinusoidal amplitudes can serve to compensate for recruitment of loudness incurred by the reduced dynamic range of hearing. For practical use, we will implement the speech enhancement for hearing aids through the computer so that the hearing impaired can access all kinds of voiced services.