My question mean, if human has a problem in his voice -he can speak but no one can her hem- I want to design circuit put it on his throat to sense his non-hearing frequency and convert it to hearing voice.
Note:
- this circuit may convert this frequency to low voice then will enter it to amplifier to amplify this voice.
I'm not aware of people who can produce sounds outside the frequency range of normal human hearing, but as Bradtherad noted, you can use a heterodyning method to shift the frequency.