Noise removing for time-variant vocal signal by generalized modulation

Since the instantaneous frequencies of vocal signals always vary with time, it is inconvenient to use the conventional filter to remove the noise of vocal signals. In this paper, we propose a method that uses the generalized modulation to reshape and minimize the areas of the spectrograms of vocal signals. Instead of multiplying an exponential function with the first order phase, the generalized modulation is to multiply an exponential function whose phase is a higher order polynomial. With the proposed noise-removing algorithm based on generalized modulation, the signal part and the noise part of a vocal signal can be well separated and the effect of noise can be significantly reduced.