Objective and subjective comparison of audio restoration methods

This paper presents the results of a perceptual test to evaluate the quality of different audio restoration algorithms based on ShortTime Spectral Attenuation method and on Kalman filter. The protocol by International Communication Union (ITU.R P.800) was used. A set of audio stimuli played with different instruments (i.e., different bandwidths, transients, and timbre) was selected and different impulsive and broadband noises were added. Commercial software and proprietary algorithms were used to restore the corrupted stimuli. Twelve subjects were asked to compare the restored and the noise free recordings. Statistical multivariate analysis was performed and accurate characterization of the restoration techniques used was achieved. In order to correlate perceptual results with acoustic characteristics of the different stimuli, a time-frequency analysis was performed. These results permitted to relate the esthetic judgement categories used by listeners with the main features of the restoration techniques used.