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

Answer 1

[Mathieu NOE]

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')); 

  

[ngoc quy hoang ngoc quy]

hello Mathieu NOE. I mean calculate value overall of 1/3 poctave band (as show by bar color red in picture)

[ngoc quy hoang ngoc quy]

hello Mathieu NOE, why +200 in code bar(1:length(f),20*log10(P)+200) ??

[Mathieu NOE]

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]

wonderful!. Can you help me in code: [data,fs] = audioread('D00002.WAV');

now, [data, fs] is different with Fs = 44.1E3 and xInp = rand(1,2^16). What will the input be now of poctave??

[Mathieu NOE]

here you are, I tested on mono and stereo wav files , also with different sampling frequencies

  [data,fs] = audioread('D00002.WAV');
  [P,f] = poctave(data,fs,'FrequencyLimits',[20 round(fs/2.2)],'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')); 
  
  if size(data,2)>1
      legend('octave levels CH1','octave levels CH2','total CH1','total CH2');
  else
      legend('octave levels','total');
  end
  hold off 

[ngoc quy hoang ngoc quy]

thank you. but I run code of you matlab error in comanwindow, you can fix error help me?

octave

Unrecognized function or variable 'xticklabel_rotate'.

Error in octave (line 15)

set(gca,'XTickLabel',{f; 'total'});set(xticklabel_rotate([],60),'color',get(gca,'xcolor'));

[ngoc quy hoang ngoc quy]

hi Mathieu NOE. help me. error in show

[Mathieu NOE]

ok sorry

you need the attached function

otherwise remove the piece of code with xticklabel_rotate

[ngoc quy hoang ngoc quy]

ok

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??

[Mathieu NOE]

yeap ! you're right !!