Project Presentation Discrete Time Signal Processing
The Designing Of Audio Equalizers Using Low Pass, High
Pass & Band-pass Filters
by
Muhammad Akbar Ali Khan & Muhammad Ashfaq
Abstract
Description 3-band Simplest multiband equalizer
Low Pass Filter
Band Pass Filter
High Pass Filter
Woofer
Mid Rang
e Speaker
Tweeter
sound
Why we chose this topic
WE have a “little!” study of the low-pass ,high-pass and band-pass filters in various DSP courses , so instead of selecting some robot-science-oriented project, we tried to do something related…
Introduction Background study Equalization :is the process of changing
the frequency envelope of a sound in audio processing. In passing through any channel, an audio signal will "spread" from its original qualities. The goal of equalization is to correct, or make equal,
the frequency response of a signal. Some kinds of EQ
A peaking equalizer A parametric equalizer Shelving-type equalizers Graphic equalizers
Introduction(cont’d)
Applications Equalization is used to compensate for
the discrepancies of a room’s acoustics Early telephone systems used
equalization to correct for the reduced level of high frequencies in long cables.
live event, where microphones and speakers operate simultaneously.
Equalization was also applied to correct the response of the transducers
Methodology
Explaining your approach / algorithm
Designing Equalizer in Maltlab Use of filters.
Designing Equalizer in VDSP++ Using FDA tool, designing filters. Importing filters to VDSP++.
Block diagram of the whole project
Sound file
Low pass filter
High pass filter
Band pass filter Convolutionprocess
WriteTo file
Explanation of The Approach we Used:
[x,fs]=wavread('sound.wav'); Wn=0.30; N=150; gLP=1; gBP=1.5; gHP=1.5; LP=fir1(N,Wn); Wn1=[.30,.70]; BP=fir1(N,Wn1); Wn2=0.70; HP=fir1(N,Wn2,'high'); figure(1) freqz(LP); figure(2)
freqz(BP); figure(3) freqz(HP); y1=conv(LP,x); y2=conv(LP,x); y3=conv(LP,x); yA=gHP*y3; wavwrite(yA,fs,'Equlizer3'); yB=gHP*y1; wavwrite(yB,fs,'Equlizer1'); yC=gHP*y2; wavwrite(yA,fs,'Equlizer2'); yD=yA+yB+yC; wavwrite(yD,fs,'Equlizer4');
Results And Discussion
Results And Discussion (cont’d)
Matlab Code Simulation
Results And Discussion (cont’d)
VDSP++ Simulation
Sound effects for an equalizer
Input Sound file Low Pass Output Band Pass Output High Pass Filter Total Output
References
Websites www.google.com www.wikipedia.com Books “Discrete Time Signal Processing” By
Alan V Oppenheim. “DSP First” By James H. McClellan,
Ronald W. Schafer & Mark A. Yoder.
Thanks.