Implementation of FIR Filter using Adjustable Window Function and Its Application in Speech Signal Processing

Digital filter plays an important role in digital signal processing applications. Digital filter can also be applied in speech processing applications, such as speech filtering, speech enhancement, noise reduction and automatic speech recognition among others. In this paper Matlab program is used to implement a low-pass FIR filter using adjustable window function based on Hamming window. In some applications such as frequency spectral analysis of a signal, a small main lobe width of the window function in frequency domain is required for increasing the ability to distinguish two closely spaced frequency components without increasing the length of the filter. In this adjustable window function the width of main lobe and amplitude of the side lobe can be varied by changing the value of for a fixed length. The comparisons of low pass FIR filters for different values of are shown. Designed low-pass FIR filter is used in the speech filtering application. The filter is applied to a recorded speech signal to remove highfrequency components of the speech signal. Signal comparison in time and frequency domain between filtered speech and original speech shows that a high frequency component of the original speech signal successively eliminates by using this low pass filter. Keywords-FIR filters, Window function, Hamming Window, Low-pass filter, FFT, IFFT, Speech Signal.