Title :
Programmable master hearing aid with adaptive noise reduction using a TMS320-20
Author :
Dillier, Norbert
Author_Institution :
Univ. Hospital, Zurich, Switzerland
Abstract :
A TMS320-20-based coprocessor in a PDP 11/73 was chosen as key element of a programmable digital master hearing aid. The system includes 16-bit A/D (analog-to-digital) and D/A with antialiasing filters, programmable attenuators, and a touch-screen terminal for patient interaction. A multiband compression table with amplitude correction factors for 64 frequency bands is generated from estimated loudness growth or isoloudness functions of hearing-aid candidates and transferred via DMA (direct memory access) into the TMS320-20 data RAM. Processing steps for input signals include A/D-conversion at 10 kHz, radix-4-FFT (fast Fourier transform) frequency-dependent amplitude spectrum modification, inverse FFT, windowed overlap-add, D/A-conversion. Prior to amplitude compression, the amplitude spectrum may be modified by an adaptive pseudocepstrum noise-reduction algorithm
Keywords :
computerised signal processing; handicapped aids; hearing aids; interference suppression; medical computing; 10 kHz; 16 bit; ADC; DAC; DMA; PDP 11/73; TMS320-20 coprocessor; adaptive noise reduction; amplitude correction factors; antialiasing filters; data RAM; direct memory access; fast Fourier transform; frequency bands; frequency-dependent amplitude spectrum modification; input signals; inverse FFT; isoloudness functions; loudness growth; multiband compression table; programmable attenuators; programmable digital master hearing aid; radix-4-FFT; touch-screen terminal; windowed overlap-add; Amplitude estimation; Attenuators; Auditory system; Coprocessors; Filters; Frequency estimation; Noise reduction; Random access memory; Read-write memory; Signal processing;
Conference_Titel :
Acoustics, Speech, and Signal Processing, 1988. ICASSP-88., 1988 International Conference on
Conference_Location :
New York, NY
DOI :
10.1109/ICASSP.1988.197153
