FILTER COEFFICIENTS

an interval of the original signal from -M:M [9]. It is important that the main energy of the impulse response is preserved within the truncated region [10].

The truncation performed above has the same effect as windowing with a rectangular window, however, on its own it is a relatively poor window choice for audio filters [11] due to the abrupt edges. Both the Hann and Hamming windows were tested on the impulse response, with the Hann window proving to be the most suitable as it takes the edges of the truncated impulse response down to zero exactly. Tapering to zero helps to preserve the shape of an ideal frequency response [fig 14].

Figure 13. Impulse Response Before and After Windowing (Hann)