Modelling and enhancement of reverberant speech using an envelope convolution method

Acoustic environments can be treated as linear systems whose transmission properties are given by their impulse response functions. This basic model can be extended, under certain conditions, to describe the relationship between the envelopes of the input and output waveforms. Such a model is proposed in the context of a multiband processing scheme, aiming at the enhancement of single microphone recorded reverberant speech signals. The specific requirements of this model permit a simplified approach to the estimation of the envelope functions. The model allows accurate evaluation of the envelope of the reverberant speech, even when little prior information about the room characteristics is available. Speech enhancement can be then achieved after envelope deconvolution in each band, which recovers the envelope of the anechoic signal from the measured speech envelope, and final reconstruction of the speech waveform using the original phase function.