Frequency offset correction in speech without detecting pitch

摘要

Radio-transmitted speech sometimes contains a residual frequency shift or offset, resulting from incorrect demodulation in single-sideband channels. Frequency-shifted speech can mask speaker identity and reduce intelligibility. Therefore, frequency offset will degrade the performance of downstream speech technologies. Existing offset correction methods require a pitch estimate of the speech signal, which is difficult in noisy radio channels. We present a new, automatic algorithm for detecting and correcting frequency offset, based on third-order modulation spectral analysis. Our method is remarkably simple and does not require pitch estimation. We provide derivations, examples, and a pilot study demonstrating how offset correction improves speaker verification for radio-transmitted speech.