Seligman P M, Patrick J F, Tong Y C, Clark G M, Dowell R C, Crosby P A
Acta Otolaryngol Suppl. 1984;411:135-9.
A 22-electrode implantable hearing prosthesis uses a wearable speech processor which estimates three speech signal parameters. These are voice pitch, second formant frequency and flattened spectrum amplitude. The signal is monitored continuously for periodicity in the range 80-400 Hz and, if this is present, stimulation occurs at the same rate. Otherwise, as in the case of unvoiced sounds, it occurs at the random rate of fluctuation of the signal envelope. The second formant is obtained by filtering to extract the dominant peak in the midband region and by continuous measurement of the zero crossing rate. The amplitude measured is that of the whole speech spectrum, pre-emphasized by differentiation. The values that are presented to the patient are the parameter estimates immediately prior to the stimulation pulse. Second formant frequency is coded by selection of an appropriate electrode in the cochlea and amplitude by a suitably controlled current. Automatic gain control is used to keep the dynamic range of the amplitude estimate within the 30 dB range of the circuitry.
一种22电极植入式听力假体使用一种可穿戴语音处理器，该处理器估计三个语音信号参数。这些参数是音高、第二共振峰频率和平坦频谱幅度。持续监测信号在80 - 400赫兹范围内的周期性，如果存在这种周期性，则以相同速率进行刺激。否则，如在清音的情况下，刺激以信号包络的随机波动速率发生。第二共振峰是通过滤波提取中频区域的主导峰值并连续测量过零率获得的。测量的幅度是整个语音频谱的幅度，通过微分进行预加重。呈现给患者的值是紧接在刺激脉冲之前的参数估计值。第二共振峰频率通过在耳蜗中选择合适的电极进行编码，幅度通过适当控制的电流进行编码。自动增益控制用于将幅度估计的动态范围保持在电路的30分贝范围内。
