DSP-implementation Of A Multiband Loudness Correction Hearing Aid
Thomas Fröhlich, Norbert Dillier · 2005
A new multiband loudness correction algorithm for digital hearing aids has been implemented on a digital signal processor (TMS320C25, TI). The short-time amplitude spectrum of the input signal is amplified and compressed according to patient specific lookup tables. Loudness scaling at different frequencies with normal hearing and hearing impaired subjects is performed to obtain frequency and intensity specific gain factors. The loudness of speech signals is estimated using a psychoacoustic model approximation at the frequency bands of maximum energy concentration. After transformation of the signal into the residual auditory field of the hearing impaired subject, the processed signal is perceived at a natural loudness. Speech test results with 5 hearing impaired subjects using their own conventional hearing aid and the new MLC-algorithm are presented.