Abstract: A bone conduction hearing aid includes a vibrator carried by the insertion end of the hearing aid. When the hearing aid is inserted into the ear canal of a patient, the vibrator is positioned in the ear canal adjacent the mastoid bone. A microphone receives sound waves and outputs a microphone signal to the hearing aid electronics where the microphone signal is amplified and then sent to the vibrator, causing the vibrator to vibrate. Vibrations produced by the vibrator are transferred to the opposite cochlea by way of the mastoid bone, enabling enhanced hearing perception in patients with hearing loss in one ear. Transfer of vibrations to the bones of the middle ear also assists patients with conductive pathology in one ear. The hearing aid may also function to enhance communication in high noise environments. Feedback from the vibrator to the microphone is eliminated electronically. Various alternate forms of feedback elimination are also contemplated by the invention.
Abstract: A hearing aid includes a microphone (1), a signal-transmission unit (2, 3,) for forming or otherwise processing the signal, an output amplifier (4) to which an earphone (10) is connected, and a battery as the power supply. The output amplifier (4) is implemented essentially as a .SIGMA.-.DELTA. amplifier and is connected to a pulse generator (8) which produces a high-frequency pulsed clock signal in the 1 MHz region. A series-connected low-pass filter (15) is also provided. The input signal to the signal converter is a representation, produced by signal processing in the transmission unit, of the low-frequency input signal to the hearing aid, this signal being converted in the signal converter into a binary signal. The output signal (14) thus appears, after passing through the low-pass filter, essentially as an amplified copy of the low-frequency input signal.