An adaptive spectral subtraction algorithm for speech enhancement in cochlear implant

On account of traditional spectral subtraction speech enhancement method usually exists scrap 'musical noise' phenomenon,the auditory perception speech quality from CI users will be affected if the traditional spectral subtraction algorithm is used in Cochlear Implant(CI)speech enhancement.To improve the noise immunity of CI,this paper introduces an adaptive order spectral subtraction algorithm and applies it to CI speech enhancement.According to the relationship between CI electrodes and frequency bands,in this algorithm the noisy speech power spectrum is divided into Bark subbands,and the coefficients and orders of the spectral subtraction in each subband are calculated according to the S/N rates.As a result,the improved method suppresses noise more balanced in each sub-bands and ultimately eliminates the 'musical noise' produced by traditional spectral subtraction.The ACE synthesis simulation based on the proposed method and subjective listening test results show that,compared with traditional spectral subtraction,the proposed method can suppress the background noise and the residual noise more effectively,and the CI synthesized speech is apperceived much more comfortable and clearer.