how to calculate sound level (spL) audio file (*.wav) ?

calculate sound level

Answer 1

[jibrahim]

Hi ngoc,

You can use splMeter from Audio Toolbox.

% EXAMPLE: Calculate sound pressure level of signal
audFileName = 'FunkyDrums-44p1-stereo-25secs.mp3';

scope = timescope('SampleRate',Fs,...
    'TimeSpanSource','property',...
    'YLimits',[20 110], 'AxesScaling','auto',...
    'ChannelNames',...
    {'LAF', 'LAeq', 'LApeak', 'LAmax'});

sm = splMeter('TimeWeighting', 'Fast',...
    'FrequencyWeighting', 'A-weighting',...
    'SampleRate', Fs, ...
    'TimeInterval',2,...
    'CalibrationFactor',1);

x = audioread(audFileName);
[LAF,LAeq,LApeak,LAmax] = sm(x(:,1));
scope([LAF,LAeq,LApeak,LAmax])

[ngoc quy hoang ngoc quy]

thank you, But problem is.

I want to calculate the sound pressure level third ooctave using poctave function

I used poctave function to convert pressure data (p) (time,pressure) to 1/3 octave spectrum

[P3rd, cf] = poctave(p,fs,'FrequencyLimits',[df,fs/2],'BandsPerOctave',3);

In order to calculate the SPL-1/3 Octave (sploct)

sploct = 10*log10(P3rd/pref^2);

Is the equation for calculating SPL-1/3 octave is correct or not?

can you help me?

[Jimmy Lapierre]

One thing that appears to be missing is a calibration for your input (in addition to pref). The advantage of using splMeter is that it includes a method to calibrate your microphone level, so you don't have to do that by yourself.

[ZHU z]

hi jibrahim~

thanks for your codes~

When I run it matlab says: "undefined function or variable 'Fs'.

Error Calculate_sound_pressure_level_of_signal (line 4)

scope = timescope('SampleRate',Fs,..."

How should I handle this issue? Can you tell me, thanks a lot~

[jibrahim]

Sure. Use this call to audioread and move it up (before the definition of scope)

[x,Fs] = audioread(audFileName);

[ZHU z]

Thanks jibrahim~

Sorry to bother you again,I moved the "[x,Fs] = audioread(audFileName);" up as you said, but still the same error,Is it because I am missing something?

% EXAMPLE: Calculate sound pressure level of signal
[x , Fs] = audioread('SAODIJI.wav');
scope = timescope('SampleRate',Fs,...
    'TimeSpanSource','property',...
    'YLimits',[20 110], 'AxesScaling','auto',...
    'ChannelNames',...
    {'LAF', 'LAeq', 'LApeak', 'LAmax'});

sm = splMeter('TimeWeighting', 'Fast',...
    'FrequencyWeighting', 'A-weighting',...
    'SampleRate', Fs, ...
    'TimeInterval',2,...
    'CalibrationFactor',1);

[LAF,LAeq,LApeak,LAmax] = sm(x(:,1));
scope([LAF,LAeq,LApeak,LAmax])

[jibrahim]

That code works for me. what is the error?

[ZHU z]

thanks, jibrahim~

the error is ："Undefined function or variable 'timescope'."(line 3) scope = timescope('SampleRate',Fs,...

% EXAMPLE: Calculate sound pressure level of signal
[x , Fs] = audioread('SAODIJI.wav');
scope = timescope('SampleRate',Fs,...
    'TimeSpanSource','property',...
    'YLimits',[20 110], 'AxesScaling','auto',...
    'ChannelNames',...
    {'LAF', 'LAeq', 'LApeak', 'LAmax'});

sm = splMeter('TimeWeighting', 'Fast',...
    'FrequencyWeighting', 'A-weighting',...
    'SampleRate', Fs, ...
    'TimeInterval',2,...
    'CalibrationFactor',1);

[LAF,LAeq,LApeak,LAmax] = sm(x(:,1));
scope([LAF,LAeq,LApeak,LAmax])

[ZHU z]

So I'm guessing I'm missing some files?

[jibrahim]

OK, it looks like your version of MATLAB does not have timescope. You can use dsp.TimeScope instead.

[ZHU z]

thank you @jibrahim~