Window technique is widely used in speech
processing to enhance the quality of speech by using it in
the design of FIR filters for removing or reducing noise
components associated with speech signal propagation or
transmission. Such noise components include Additive
White Gaussian Noise (AWGN), Random Noise, power
line noise, high and low frequency noise components. The
information content of any contaminated speech signal is
unreliable unless these noise components are removed.
This paper presents a FIR filter designed with double-
cosine term generalised adjustable window with to denoise
speech signal of high frequency noise components. The
speech signal is recorded as windows media audio (.wma)
format and as such the optimal sampling frequency is
44100Hz while the filter order is 34. A real voice
statement, “Education is the Key to the Development of
any Nation” is transduced to electrical form with the in-
built microphone of a laptop system, recorded in windows
media audio (.wma) format and stored in a file in the
system. With “audioread” instruction the stored voice is
loaded into a matlab work space. A noise component of
4500Hz and above is generated with matlab and mixed
with the speech to obtain a contaminated speech signal.
The designed filter is able to effectively denoise the
contaminated speech signal when it is applied to it.
Keywords : Adjustable Window, Double-Cosine Term, Speech Signal, High Frequency Noise, Power Spectral Density.