In signal processing, spectral leakage is the creation by an operation on a signal of new frequency components that were not there before. This unwanted effect occurs when computing the [[short-time Fourier transform (STFT)]] and other forms of [[short-time processing]]. Spectral leakage occurs as a result of the [[windowing]] of the signal. When the signal is periodic because the frequency response of the [[window function]] is not zero outside its main lobe, the amplitude of one harmonic leaks over the rest and masks other frequency values. The side lobe amplitude is one of the [[spectral features of window functions]] that influence spectral leakage. ![[Comparison_of_spectral_leakage_of_several_window_functions.svg]] [Wikimedia](https://commons.wikimedia.org/wiki/File:Comparison_of_spectral_leakage_of_several_window_functions.svg) spectral leakage of several window functions.