Many audio effects such as reverb, chorus and flanger, use some form of the delay function. In addition, straight delay functions are used to synchronize audio to video. Echo effect and its various forms, such as doubling echo or slapback echo are commonly used in audio industry. In our implementation, delay refers to sounds combined with delayed version of itself. The delay effect usually results in certain frequencies being canceled out if the length of the delay is such that the output of the delay is an inverted form of its input. Because the frequency response for this effect consists of several evenly spaced symmetric peaks, similar to a comb, it is referred to as a 'comb filter response'.