Patent ID: 9532148
Filing Date: 2016-12-27
CPC Classification: G10L,H04R

Claim Text:
1. A method of processing a signal in a hearing aid, the method comprising the steps of: receiving an input signal from an acoustical-electrical transducer; splitting the input signal into a multitude N of hearing aid frequency bands using a first filterbank; estimating ambient speech level and noise level in a multitude of said hearing aid frequency bands and applying a hearing aid gain to said speech level and noise level in said multitude of hearing aid frequency bands, whereby estimated speech and noise spectra are provided; estimating hearing loss levels in said multitude of said hearing aid frequency bands hereby providing an estimated hearing loss spectrum; providing excitation values for the speech and noise in said multitude of hearing aid frequency bands, by using an auditory model of the cochlea for a hearing impaired person, and the estimated speech, noise and hearing loss spectra; using said excitation values to calculate a speech intelligibility measure; and optimizing said speech intelligibility measure by iteratively varying the applied gain in the hearing aid frequency bands, wherein the step of providing the excitation values comprises the steps of: applying a frequency dependent gain to the estimated speech and noise spectra, wherein said frequency dependent gain is adapted to account for the acoustical effect of the middle ear; providing a second filter bank having N band-pass filters with center frequencies corresponding to those of said first filter bank; filtering the estimated speech and noise spectra in a filter of said second filter bank, hereby providing first filtered speech and noise spectra; integrating as a function of frequency said first filtered spectra to obtain a first intermediate excitation value at the output of said filter from the second filter bank; providing a third filter bank having N band-pass filters with center frequencies corresponding to said first filter bank; determining the transfer function of a filter from said third filter bank using the first intermediate excitation value at the output of said filter from the second filter bank and using an estimate of the hearing loss due to outer hair cell loss; filtering the estimated speech and noise spectra in said filter of said third filter bank, hereby providing second filtered speech and noise spectra; integrating as a function of frequency said second filtered spectra to obtain a second intermediate excitation value at the output of said filter from the third filter bank; and adding the first and second intermediate excitation values, hereby providing an excitation value, for that specific hearing aid frequency band, to be used for calculating a speech intelligibility measure.