how to plot bar overall 1/3 octave by Poctave() as show below(bar color red)?

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ngoc quy hoang ngoc quy 2021-2-26

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评论： Mathieu NOE 2021-3-1

采纳的回答： Mathieu NOE

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Mathieu NOE 2021-2-26

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hello

see example below :

  Fs = 44.1E3;
  xInp = rand(1,2^16);
  % Compute the octave spectrum of the same signal, but this
  % time, use a A-Weighting filter. Visualize the spectrum.
  [P,f] = poctave(xInp,Fs,'FrequencyLimits',[20 20E3],'FilterOrder',6,'BandsPerOctave',3,'Weighting','A');
  f = round(f);
  
  figure(1), bar(1:length(f),20*log10(P)+200)
  xlabel('Hz');
  ylabel('Amplitude (dB(A))');
  set(gca,'XTick',1:length(f));
  set(gca,'XTickLabel',f);set(xticklabel_rotate([],60),'color',get(gca,'xcolor')); 
  

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Mathieu NOE 2021-2-26

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hello

i am not 100% sure , but for me poctave output is power (and not amplitude) , so the total power is the simple sum of all bands power; (I usually do not use poctave but an older 1/3 octave package)

so I changed the dB from 20 to 10 x log10

next I added the bar with the sum, but this will be the sum of the weighted spectrum, if you need both sums (unweighted and weighted) then you need to add one more computation

also I changed the + 200 which is supposed to micmic a dB ref of 20 micro pascal = a vertical shift of + 94 dB

hope this is helpful

  [P,f] = poctave(xInp,Fs,'FrequencyLimits',[20 20E3],'FilterOrder',6,'BandsPerOctave',3,'Weighting','A');
  f = round(f);
  P_global = (sum(P)); % sum of power 
  
  ref = -20*log10(20e-6); % ref to 20 micro Pascal
  clf
  figure(1), 
  bar(1:length(f),10*log10(P)+ref)
  hold on 
  bar(length(f)+1,10*log10(P_global)+ref)
  xlabel('Hz');
  ylabel('Amplitude (dB(A))');
  set(gca,'XTick',1:length(f)+1);
  set(gca,'XTickLabel',{f; 'total'});set(xticklabel_rotate([],60),'color',get(gca,'xcolor')); 
  legend('octave levels','total');
  hold off 

ngoc quy hoang ngoc quy 2021-2-27

编辑：ngoc quy hoang ngoc quy 2021-2-27

but i think the poctave function output is sound power not Sound Pressure so Sound Pressure Level (SPL) does not calculate instead it will calculate sound power level ( LwA) by LwA = 10*log10(P/P0) with P0 = 10e-12 w.

I want to hear your opinion on that matter??