Epoch extraction in high pass filtered speech using hilbert envelope

Abstract

Hilbert envelope (HE) is defined as the magnitude of the analytic signal. This work proposes HE based zero frequency filtering (ZFF) approach for the extraction of epochs in high pass filtered speech. Epochs in speech correspond to instants of significant excitation like glottal closure instants. The ZFF method for epoch extraction is based on the signal energy around the impulse at zero frequency which seems to be significantly attenuated in case of high pass filtered speech. The low frequency nature of HE reinforces the signal energy around the impulse at zero frequency. This work therefore processes the HE of high pass filtered speech or its residual by zero frequency filtering for epoch extraction. The proposed approach shows significant improvement in performance for the high pass filtered speech compared to the conventional ZFF of speech. Index Terms: Epochs, zero frequency filtering, Hilbert envelope