Abstract:
Programmable hybrid hearing aid with digital signal processing comprising a main section (1) which can be inserted in the meatus (6). The main section (1) comprises an open connection between the ear opening and an inner portion of the meatus (6), providing an acoustic transmission channel with low-pass characteristic and resonant amplification. The main section further comprises an electroacoustic transmission channel based on digital signal processing and a signal processor (DSP) and with possibility for suppressing a possible acoustic signal feedback through the acoustic transmission channel. A variant of the hearing aid is provided with a microphone (M1) and the feedback signal is suppressed by digital filtering. Another variant of the hearing aid employs two microphones (M1.M2). and the feedback signal may then be suppressed by phasing out before the digital signal processing, while the digital signal processing also comprises cancellation of the feedback signal in case of high gain. A number of response functions are stored in a memory (RAM2) in a control unit and is freely chosen by the user in regard of adaption to hearing function and acoustic environment. All the electronics of the electroacoustic channel in the hearing aid is implemented as a monolithic integrated circuit (3) in CMOS technology.
Abstract:
A miniaturized electrodynamic sound generator comprises a diaphragm, a permanent magnet with pole pieces, a magnet yoke, and a coil. The yoke is designed such that is constitutes a housing or a cabinet of the sound generator. The permanent magnet and the pole pieces are provided in a recess in the cabinet or the yoke and surrounded by the coil, which is connected to the diaphragm at a peripheral area thereof. The diaphragm is provided above the magnet system of the recess and fastened to the outside of the cabinet. The dynamic response of the sound generator is determined by the magnetic, electrical, mechanical, and acoustic parameters which are used in the design of the sound generator. By varying some of these parameters, the frequency and amplitude of a resonance may be chosen such that the sound generator may reconstruct the natural acoustic transfer function in the range of 2-4 kHz in the human meatus. This makes the sound generator particularly suitable for use in hearing aids.