This soccer season, denoising the noise from the vuvuzela has become very popular, as many fans find the noise from this instrument distracting from the game. In this example, we analyze the vuvuzela spectrum and identify its fundamental and first few harmonic frequencies. We then use parametric equalizers to selectively filter out these frequencies.
Notch parametric equalizers are used to remove the vuvuzela frequencies. As the notch filters may also remove components of the speech signal at the vuvuzela frequencies, a peak parametric equalizer is used to boost the speech signal at the output of the notch filters.
Stream processing techniques are used to process the input audio in "frames", and the filtering is done in a stream processing loop as well. Output audio is stored as a WAV file, and also logged to the MATLAB workspace, where the output results can be analyzed further.