Extracting a segment from sound file

Hi,

I have a wave file of 100 seconds. And I have a excel file where I marked some areas of that file with start and stop times. like first segment: 2.5 to 3.4 seconds, second segment: 4.6 to 5.2 seconds and so on.

Now, I want to do the following things:

1. I first read the wav file, 2. then read the excel file for start and stop times, 3. then cut the segments from the wave file according to the excel file.

I know the 1st and 2nd part. but stuck in the 3rd one. Please let me know, how to do the 3rd part for this.

[Image Analyst]

It would make it easier for people to develop some simple code for you if you attached the wav and xlsx files.

[Odrisso]

Hi Analyst,

Here is the code: Here tt is the file with two columns which I extracted from excel.

• [x,fs] = audioread('15.wav');
• [M,N] = size(x);
• L = size(tt,1);
• for k = 1:L
• a = x(tt(k,1)*fs+1:tt(k,2)*fs);
• end

By a, I can find the amplitude values for all marked areas.

But, when I want to see separately each individual area, it shows error of dimensional mismatch. I know this error come because the dimension is not same for each marked file. Now, I can't zero pad them because if I do so the average value will be changed.

So, please let me know, how can I extract every segment and store in different variables.

[Image Analyst]

I think this was maybe a reply for Rick. I didn't ask for this. I suggested you attach the two files . You can still do that. Click paperclip, then "Choose file" then "Attach file". You have to do each one at a time, you can't multi-select files.

Answer 1

[Rick Rosson]

Here are a few pages from the documentation that will help:

• audioread
• xlsread
• logical indexing

And here is a possible solution that should get you started:

   [x,Fs] = audioread('myaudiofile.wav');
   [M,N] = size(x);
   dt = 1/Fs;
   t = dt*(0:M-1)';

   figure;
   plot(t,x);

   segments = xlsread('mydatafile.xlsx','C15:D24');

   L = size(segments,1);

   for k = 1:L
       idx = ( segments(k,1) < t )  &  ( t < segments(k,2) )  ;
       figure;
       plot(t(idx),x(idx));
   end

[Odrisso]

HI Rosson,

thanks for your answer.

But, the excel file in the seconds(start and stop time). I need to segment the wave file according to this seconds. I mean, I want to extract the sampled data for only those seconds.

[Rick Rosson]

I had not finished my answer yet. Please check it now.

[Odrisso]

Hi ,

Thanks a lot. But, I don't want to plot them. I just want to save them in a variable. So from your code I develop this:

Here is the code: Here tt is the file with two columns which I extracted from excel.

• [x,fs] = audioread('15.wav');
• [M,N] = size(x);
• L = size(tt,1);
• for k = 1:L
• a = x(tt(k,1)*fs+1:tt(k,2)*fs);
• endBy a, I can find the amplitude values for all marked areas.

But, when I want to see separately each individual area, it shows error of dimensional mismatch. I know this error come because the dimension is not same for each marked file. Now, I can't zero pad them because if I do so the average value will be changed.

So, please let me know, how can I extract every segment and store in different variables.