THEMODIFIED CONSTANT Q SPECTROGRAM(MCQS) AND ITS APPLICATION TO PHASE VOCODING

Abstract

This thesis discusses the development of amodified constant Q spectrogram representation which is invertible in a least-squares sense. A good quality inverse is possible because this modified transform method, unlike the usual sliding window constant Q spectrogram, does not discard any data samples when performing the variable length discrete Fourier transforms on the original signal. The development of a phase vocoder application using this modified technique is also discussed. It is shown that MCQS phase vocoding is not a trivial extension of the regular FFT-based phase vocoder algorithms and some of the mathematical subtleties related to phase reconstruction are addressed.