Given an original speech segment “speech.dat” sampled at 8000 Hz with each sample encoded in 16 bits, use Programs 2.3–2.5 and modify Program 2.2 to quantize the speech segment using 3–15 bits, respectively. The SNR in dB must be measured for each quantization. MATLAB function: “sound(xmax(abs(x)),fs)” can be used to evaluate sound quality, where “x” is the speech segment while “fs” is the sampling rate of 8000 Hz. In this project, create a plot of the measured SNR (dB) versus the number of bits and discuss the effect of the sound quality. For comparisons, plot the original speech and the quantized one using 3, 8, and 15 bits. (a) Program 2.2 MATLAB program for Example 2.14.%Example 2.14clear all; close alldisp('load speech: We');load we.datsig = we;fs=8000;% Load speech data at the current folder% Provided by the instructor% Sampling rate% Length of signal vector% Sampling periodlg=length(sig);T=1/fs;CoCHAPTER 2 SIGNAL SAMPLING AND QUANTIZATIONEXAMPLE 2.14–CONT'Dt=[0:1:lg-1]*T;sig=4.5*sig/max(abs(sig));Xmax = max(abs(sig));Xrms = sqrt( sum(sig .* sig) / length(sig))disp('Xrms/Xmax’)k=Xrms/Xmax% Time instants in second% Normalizes speech in the range from -4.5 to 4% Maximum amplitude% RMS valuedisp('20*log10(k)=>');k = 20*log10(k)bits = input('input number of bits =>');lg = length(sig);for x=1:lg[Index(x) pq]=biquant(bits, -5,5, sig(x));%Output quantized index.end% transmitted% receivedfor x=1:lgqsig(x) = biqtdec(bits, -5,5, Index(x));end%Recover the quantized value%Calculate the quantized errorqerr = sig-qsig;subplot(3,1,1);plot(t,sig);ylabel('Original speech');title(we.dat: we');subplot(3,1,2);stairs(t, qsig);gridylabel('Quantized speech')subplot(3,1,3);stairs(t, qerr);gridylabel('Quantized error’)xlabel('Time (sec.)');axis([0 0.25 –1 1]);disp('signal to noise ratio due to quantization noise')snr(sig,qsig)% Signal to noise ratio in dB:% sig = original signal vector,% qsig =quantized signal vector Program 2.3. MATLAB function for uniform quantization encoding.function [ I, pq]= biquant(NoBits,Xmin, Xmax,value)% function pq = biquant(NoBits, Xmin, Xmax, value)% This routine is created for simulation of uniform quantizer.% NoBits: number of bits used in quantization.% Xmax: overload value.% Xmin: minimum value% value: input to be quantized.% pq: output of quantized value% I: coded integer indexL=2^NoBits;delta=(Xmax - Xmin)/L;I=round ((value-Xmin)/delta);if ( I==L)I=I-1;endif I<0I=0;endpq=Xmin+I*delta;Program 2.4. MATLAB function for uniform quantization decoding.function pq =biqtdec(NoBits,Xmin,Xmax,I)% function pq = biqtdec(NoBits,Xmin, Xmax, I)% This routine recover the quantized value.%% NoBits: number of bits used in quantization.% Xmax: overload value% Xmin: minimum value% pq: output of quantized value% I: coded integer indexL=2°NoBits;delta=(Xmax - Xmin)/L;pq=Xmin+I*delta;Program 2.5. MATLAB function for calculation of signal-to-quantization noise ratio.function snr = calcsnr(speech, qspeech)% function snr = calcsnr(speech, qspeech)% this routine is created for calculation of SNR% speech: original speech waveform.% qspeech: quantized speech.% snr: output SNR in dB.qerr = speech-qspeech;snr = 10*1og10(s um(speech.*speech)/sum(qerr.*qerr))

Solution :: Enter the following code in MATLAB [y fs]=audioread('speech.wav'); a=3; b=15;…

Program 2.3. MATLAB function for uniform quantization encoding. function [ I, pq]= biquant (NoBits, Xmin, Xmax,value) % function pq = biquant (NoBits, Xmin, Xmax, value) % This routine is created for simulation of uniform quantizer. % NOBits: number of bits used in quantization. % Xmax: overload value. % Xmin: minimum value % value: input to be quantized. % pq: output of quantized value % I: coded integer index L=2^NoBits; delta=(Xmax- Xmin)/L; I=round ((value-Xmin)/delta); if ( I==L) I=I-1; end if I<0 I=0; end pq=Xmin+Idelta; Program 2.4. MATLAB function for uniform quantization decoding. function pq =biqtdec(NoBits,Xmin,Xmax, I) % function pq = biqtdec(NoBits, Xmin, Xmax, I) % This routine recover the quantized value. % NOBits: number of bits used in quantization. % Xmax: overload value % Xmin: minimum value % pq: output of quantized value % I: coded integer index L=2°NoBits; delta=(Xmax- Xmin)/L; pq=Xmin+Idelta; Program 2.5. MATLAB function for calculation of signal-to-quantization noise ratio. function snr - calcsnr(speech, qspeech) % function snr = calcsnr(speech, qspeech) % this routine is created for calculation of SNR % speech: original speech waveform. % qspeech: quantized speech. % snr: output SNR in dB. qerr = speech-qspeech; snr = 101og10(s um(speech.speech)/sum(qerr.*qerr))

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE