Perceptual Speech Enhancement Using a Hilbert Transform Based Time-Frequency Representation of Speech

A new Time-Frequency (TF) representation of speech signal is introduced and used for speech enhancement. TF representation and speech enhancement algorithm are both based on perceptual properties of human auditory system in which the concept of band analysis is exploited. TF representation is carried out by the means of analytic decomposition of speech signal in the hearing Critical Bands (CB) where the envelope and phase components of the analytic signals are used. For the purpose of enhancement a time varying gain function is used which takes into account the threshold of hearing. This threshold is calculated on the basis of masking effects using a perception model. Signal is reconstructed from the modified envelopes and the phases of noisy signal decomposed in critical bands. Experiments show that using the threshold of hearing in which temporal masking is included can effectively eliminate the musical noise without a significant decrease in intelligibility. Results using noise estimation by Voice Activity Detector (VAD) and Speech Presence Probability (SPP) are reported on.