Active tone elimination algorithm using FFT with interpolation and zero-padding

This article presents a method for eliminating tonal components from acoustic signals. Tonal components are quasi-periodic signals whose amplitude, frequency and phase can change slowly with either a certain tendency or randomly. Active elimination of a single tonal component consists in adding a synthesized component with opposite polarity. The main challenge is to find a compromise between the frequency resolution and the delay resulting from the sample acquisition and the operation of the reset signal generation algorithm. The elimination is realized in three stages: detection of tonal components parameters, synthesis of the cancelling signal, addition of the cancelling signal to the input signal. Detection is carried out using the FFT transform, the resolution of which is increased by means of time windows, spectrum interpolation and zero-padding. Various methods of synthesis of the cancelling signal were also checked. An analysis of detection errors was performed compared to the standard FFT transform. An elimination simulation was also done to analyze the effectiveness of the reduction. The result of the work is the evaluation of the method for the application in the elimination of tonal components of acoustic signals as well as in systems of active reduction of narrowband noise.