GEDI: Gammachirp Envelope Distortion Index for Predicting Intelligibility of Enhanced Speech

Abstract

In this study, we proposed a new concept, gammachirp envelope distortion index (GEDI), based on the signal-to-distortion ratio in the auditory envelope SDRenv, to predict the intelligibility of speech enhanced by nonlinear algorithms. The main objective of using GEDI is to calculate the distortion between enhanced and clean speech representations in the domain of a temporal envelope that is extracted by the gammachirp auditory filterbank and modulation filterbank. We also extended the GEDI with multi-resolution analysis (mr-GEDI) to predict the speech intelligibility of sound under non-stationary noise conditions. We evaluated the GEDI in terms of the speech intelligibility predictions of speech sounds enhanced by a classic spectral subtraction and a state-of-the-art Wiener filtering method. The predictions were compared with human results for various signal-to-noise ratio conditions with additive pink and babble noise. The results showed that mr-GEDI predicted the intelligibility curves more accurately than the short-time objective intelligibility (STOI) measure and the hearing aid speech perception index (HASPI).