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.