| 摘要 |
PURPOSE:To increase effectively the intelligibility for the voce by compressing and shifting the frequency band of the aural signal into the frequency band where the loss of the hearing ability is comparatively small for the person who is handicapped in the audition. CONSTITUTION:The aural signal sent through hearing aid mike 1 undergoes the frequency step-down (1/2, for example) at divider circuit 4 after passing through preamplifier 2 and high pass filter 3 featuring the cut-off frequency of 200Hz, and is then amplified through power amplifier 5 to be converted into the voice through speaker 6. Circuit 4, using charge transfer element BBD, sets the frequency step- down ratio to the optimum level for the user by changing the slope of the saw- tooth wave at the saw-tooth wave generation circuit or varying the reading clock frequency of the clock generation circuit. |
