how i implement code for y=audiorecord(Fs,nbits,1)
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gadhamg
on 21 Mar 2018
Commented: govindaraj sangam
on 5 Jan 2021
close all;
clear all;
%%Variables
low_stop = 300;
high_stop = 1000;
WindowEnvelope = 0.1; % Length of envelope averaging filter window
MaximaWindow = 2.4; % Length of window to find local maxima
DownSamp = 200; % Frequency to downsampe envelope to (Hz)
Threshold = 0.2; % Percentage of mean maxima value that a
Fs = 8000; % Sampling Frequency
nbits = 8; % Bits of Precision When Sampling
WindowTime = 5; % Length of recorded time processed in each
%%Initialize
BreathCountTotal = 0;
Y = audiorecord(Fs,nbits,1);
meanbreath = 0;
%%Create Bandpass Filter
F=[(low_stop-100) low_stop high_stop (high_stop+100)]; % band limits
A=[0 1 0]; % band type: 0='stop', 1='pass'
dev=[0.0001 10^(0.1/20)-1 0.0001]; % ripple/attenuation spec
[M,Wn,beta,typ]= kaiserord(F,A,dev,Fs); % window parameters
b = fir1(M,Wn,typ,kaiser(M+1,beta),'noscale'); % filter design
%%Initialize
loopcount = 0;
EXIT = 1;
BreathTotal = [];
%%Initial Recoding
signal = zeros(1,Fs*WindowTime);
record(y)
while EXIT == 1
%%Counter
loopcount = loopcount + 1;
%%Filter Signal
signal_f = fftfilt(b,signal);
%%Find Envelope
signal_h = hilbert(signal_f); % Hilbert Transform
envelope = sqrt(signal_h.*conj(signal_h));
envelope_f = filter(ones(1,round(Fs*WindowEnvelope))/round(Fs*.1),1,envelope);
envelope_fDS = downsample(envelope_f,round(Fs*(1/DownSamp)));
%%Find Local Maxima
windowsize = DownSamp * MaximaWindow / 4;
BreathCount = 0;
Breath = [];
for ix = 1:length(envelope_fDS) - windowsize
maxima = max(envelope_fDS(ix:ix+windowsize));
if loopcount < 2 % Ignore first 2 loops
elseif loopcount < 100 % Use next 100 loops to get breath
threshold
if maxima == envelope_fDS(ix+windowsize/2)
BreathCount = BreathCount + 1;
Breath(BreathCount) = ix + windowsize/2;
end
else % Begin using and updating threshold
if (maxima == envelope_fDS(ix+windowsize/2)) && maxima >(Threshold * meanbreath)
BreathCount = BreathCount + 1;
Breath(BreathCount) = ix + windowsize/2;
end
end
end
BreathTotal = cat(2,BreathTotal,envelope_fDS(Breath));
meanbreath = mean(BreathTotal);
if isempty(Breath) && loopcount > 100 == 1
for i = 1:10
beep
pause(.1)
end
EXIT = 0;
end
%%Keep Recording
stop(y)
signal_new = getaudiodata(y,'double');
record(y)
signal(1:end-length(signal_new)) =signal(1+length(signal_new):end);
signal(end-length(signal_new)+1:end) = signal_new;
clear signal_new
%%Plot
figure(1)
subplot(2,1,1)
signalplot = signal;
time1 = (0:length(signalplot)-1) / (Fs/4);
refresh
plot(time1,signalplot)
title('Raw Signal')
xlabel('Time (seconds)')
ylabel('Intensity')
subplot(2,1,2)
envelopeplot = envelope_fDS;
time = (0:length(envelopeplot)-1) / (DownSamp/4);
plot(time,envelopeplot)
hold on
plot(Breath/(DownSamp/4),envelope_fDS(Breath),'rx','MarkerSize',16,'linewidth',4)
title('Envelope of Breath Signal w/ Breath Markers')
xlabel('time (sec)')
ylabel('Arbitrary Units')
hold off
end
3 Comments
Accepted Answer
Abhishek Ballaney
on 22 Mar 2018
https://in.mathworks.com/help/matlab/ref/audiorecorder.html
1 Comment
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