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 Woofe r Mid Rang e Spea ker Tweete r 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 Convolution process Write To file

Explanation of The Approach we Used:  [x,fs]=wavread('sound.wa v');  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  Books “Discrete Time Signal Processing” By Alan V Oppenheim. “DSP First” By James H. McClellan, Ronald W. Schafer & Mark A. Yoder.

Thanks.