Question

Exercise 3 -This small programming exercise is on algorithms and thir implementation with MATLAB. You are to program in MATLAB a simple echo effect algorithm that uses the FIR configuration You must design an FIR filter such that an audio echo effect (Fig. 1) is produced. simple audio synthesis and audio effects Delay Original Sound First Echo Second Echo Fig. 1. Synthetic demo of Echo effect. Design an echo effect filter using the FIR configuration. Design an FIR with two coefficients such that an echo audio echo effect Use the cleanspeech wav file form the previous MATLAB exercise as the input. Use MATLAB and plot the impulse response and frequency response of the echo filter. Plot the phase response of the filter using MATLAB Calculate the group delay Describe the value of the delay and filter such that you get strong echo effects. Can you design IIR filter working in a similar manner? Give equation and explain. can be realized.

Answer 1

close all,
clear all,
clc,

ProjectPath = pwd;
SoundFilePath = strcat(ProjectPath,'\TrainWhistle.wav');

[soundfile, Fs, nbits] = wavread(SoundFilePath);

b = fir1(200,.03,'low');
y=filter(b,1,soundfile);
size(soundfile)
size(y)
x=cat(1,soundfile,y);

freqz(b,1,512)

subplot(3,1,1);
plot(soundfile);
xlabel('--- Time (secs.) --->');
ylabel('--- Amplitude --->');
str=strcat('Time Plot of Voice Signal at Sampleing Rate = ',num2str(Fs));
title(str);

subplot(3,1,2);
plot(y); title('Echo');
subplot(3,1,3);
plot(x); title('Original Sound + Echo');
wavplay(x)

Time Plot of Voice Signal at Sampleing Rate 48000 17 Time (secs.) -- Echo x 10° 0.4 0.2 0.2 4 10 x 10 Original Sound +Echo 0.5H 2.5 x 10

50 100 150 09 08 07 0.5 200 0.4 0.3 0.2 0.1 Normalized Frequency (xn rad/sample) 200 800 09 0.8 n 2 0.5 0.4 -1000 03 0.1 0.2 Normalized Frequency (xn rad/sample) Phase (degrees) (an) apnuuew