  In the field of digital signal processing, the function of a filter is to
remove unwanted parts of the signal such as random noise that is also
undesirable. To remove noise from the speech signal transmission or to extract
useful parts of the signal such as the components lying within a certain
frequency range, filters are necessary. Filters are broadly used in signal
processing and communication systems in applications such as channel
equalization, noise reduction, radar, audio processing, speech signal
processing, video processing, biomedical signal processing that is noisy ECG,
EEG, EMG signal filtering, electrical circuit analysis and analysis of economic
and financial data. In this paper, three types of infinite impulse response
filter i.e. Butterworth, Chebyshev type I and Elliptical filter have been
discussed theoretically and experimentally. Butterworth, Chebyshev type I and
elliptic low pass, high pass, band pass and band stop filter have been designed
in this paper using MATLAB Software. The impulse responses, magnitude
responses, phase responses of Butterworth, Chebyshev type I and Elliptical
filter for filtering the speech signal have been observed in this paper.
Analyzing the Speech signal, its sampling rate and spectrum response have also
been found.
