A trial of designing phoneme-enhancing and noise-suppressing directive hearing aid with the aim of auditory support for presbyacusic listeners

我们提出了一个自适应数字滤波器，增强共振峰和辅音带噪声的过渡，以提高清晰度分数。具体内容如下：首先，为了增强辅音的共振峰过渡，我们预先生成了频率特性与人类听觉滤波器相匹配的带通滤波器。根据辅音的声学特征，采用采样频率和采样间隔对语音信号进行编码。采用选择性线性预测编码对谱线轨迹进行估计，以选择能覆盖谱线局部峰值带宽的带通滤波器。对增强后的辅音进行了清晰度测试，结果表明，增强共振峰后的辅音清晰度得到了明显改善。其次，提出了一种新的算法来检测以带噪为声学特征的辅音，如摩擦音。声音信号被分成四个带通滤波器，从中计算每个幅度作为检测的声学线索。其结果是，摩擦辅音检测与三个触发输出的带通滤波器。

We propose an adaptive digital filter which enhances transition of formants and band noise in consonants, so as to improve the articulation scores. The details are presented below.First, for enhancement of the formant transition of consonants, we beforehand generated band-pass filters whose characteristics of frequency match the human auditory filters. Sound signals were encoded by the sampling frequency and interval which were fit for acoustic features of consonants. Spectrum loci was estimated by selective linear predictive coding in order to select the band-pass filters which cover the band width of the local peaks of spectrum. The articulation test to enhanced consonants was carried out, which became evident that the editted consonants which have enhanced formant peaks improved the articulation.Second, a new algorithm was proposed to detect the consonants which have band noise as an acoustic feature, such as a fricative sound. Sound signals were separated into four band-pass filters, from which each amplitudes were calculated as acoustic cues for the detection. As a result, the fricative consonants were detected with three trigger outputs from the band-pass filters.