The linear prediction inverse modulation transfer function (LP-IMTF) filter for spectral enhancement, with applications to speaker recognition

We propose a method for spectral enhancement of reverberant speech based on inverting the modulation transfer function (MTF). Using all-pole models of modulation spectra allows the linear prediction inverse MTF (LP-IMTF) filter to exhibit a smooth frequency response, and allows it to be implemented as a low-order IIR filter in the modulation envelope domain. The proposed filter adapts to current acoustic conditions without relying on explicit information regarding reverberation time. Additionally, the LP-IMTF framework allows for estimation of useful side information, such as local signal-to-reverberation ratios and band-specific reverberation times. As example applications, the LP-IMTF system is applied to enhancement and speaker recognition of reverberant speech, and significant performance improvements are achieved.