On the application of the AM-FM model for the recovery of missing frequency bands of telephone speech

This study presents a novel technique to reconstruct the missing frequency bands of band-limited telephone speech signals. This technique is based on the Amplitude and Frequency Modulation (AM-FM) model, which models the speech signal as the sum of N successive AM-FM signals. Based on a least-mean-square error criterion, each AM-FM signal is modified using an iterative algorithm in order to regenerate the high-frequency AMFM signals. These modified signals are then combined in order to reconstruct the broad-band speech signal. Experiments were conducted using speech signals extracted from the NTIMIT database. Such experiments demonstrate the ability of the algorithm for speech recovery, in terms of a comparison between the original and synthesized speech and informal listening tests.