Plotting sound pressure level

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Alok Bendale
Alok Bendale 2019-10-18
评论： Alok Bendale 2019-11-20
Hello,
I am working on intensity probe to develop sound meter level. I did the fft and calculated sound pressure levels as well as sound power level using sound pressure level Lp=20log10(P/Pref) and sound power level Lw= Lp+5.344. The size of columns Lp and Lw is 1024x1 and size of frequency column in fft calculations is 1x513. How can I overcome this problem?
Sample rate is 16384
blocksize is 1024
frequency resolution is 50Hz
Signal is sine wave with frequency amplitude 6400
Thank you.
for i = 1 : numel(RealPa)
Lp(i, 1) = log10(RealPa(i))+ log10(100000)-log10(2); %Sound Pressure Level Calculation
end
for i=1:numel(Lp)
Lw(i,1)=Lp(i)+5.344; %Sound Power Level Calculation
end
%Beow is code for FFT
[d,s]=xlsread('CHANNEL1.xlsx');
t=d(:,1);
p=d(:,2);
L=length(t);
Ts=mean(diff(t));
Fs=1/Ts;
Fn=Fs/2;
pc=p-mean(p);
FTv=fft(pc)/L;
Fv=linspace(0,1,fix(L/2)+1)*Fn;
Iv=1:length(Fv);
figure(1)
plot(Fv,abs(FTv(Iv))*2)
grid
xlabel('Frequency in Hz')
ylabel('Amplitude in Pa')

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回答（1 个）

Soham Chakraborty
Soham Chakraborty 2019-10-22
Hi,
In order to get the sound pressure level of an audio signal, you can use the splMeter system object. You can refer to the following link for more information about it: https://www.mathworks.com/help/audio/ref/splmeter-system-object.html
You can declare the object as follows:
SPL = splMeter('SampleRate', frequency_value);
Then you can get the sound pressure level data that corresponds to that specific frequency value as follows:
[y, Fs] = audioread(name_of_file); >> [Lt,Leq,Lpeak,Lmax] = SPL(y);
You would have to repeat these steps for each one of the frequency value in the y array and form a matrix with all the sound pressure level data that corresponds to the frequency data.
You can find the time array that corresponds to the y array (the signal values) as follows:
time_in_sec = (1:size(y,1))/Fs;
  1 个评论
Alok Bendale
Alok Bendale 2019-11-20
Thank you for your response and also extremely sorry for replying so late, but I have data in terms of pressure not as an audio file. The attached file is one of the samples I have taken with two microphones.

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