Forums

Spectrogram - Axis & Energy

Started by shar...@yahoo.co.in December 30, 2010
Dear all,

I am doing research in audio processing. I have been asked to count the number of rain drops in a given audio recording. I need your precious help for the following 2 questions

1) While I was obtaining the spectrograms for the individual chunks that I created, I am getting the resulting spectrograms to be like thin strips and I had to manually zoom in to see the actual spectrogram.
Is there any code to enlarge the vertical axis of the spectrogram to make it clearly visible. Your help will be much appreciated.

2) I am able to calculate the energy of the spectrogram for individual chunks and set a threshold to obtain the count of rain drops. I need to do this for every chunk and get the energy over the entire 20 min recording.

P.S : The 20 min recording is divided into 120 chunks with 10sec interval.

I am really confused with the loop statement that does this.

Can someone help me with the loops in matlab to obtain the energy over the entire 20 min recording

Thanks in advance,
Sharath
Sharath-

If you post one of your 10 sec .wav files, I can process it and upload a meaningful spectrogram screen cap. You can
then take my parameters as a starting point in MATLAB.

-Jeff

> I am doing research in audio processing. I have been asked to count the number of rain drops in a given audio
> recording. I need your precious help for the following 2 questions
>
> 1) While I was obtaining the spectrograms for the individual chunks that I created, I am getting the resulting
> spectrograms to be like thin strips and I had to manually zoom in to see the actual spectrogram.
> Is there any code to enlarge the vertical axis of the spectrogram to make it clearly visible. Your help will be much
> appreciated.
>
> 2) I am able to calculate the energy of the spectrogram for individual chunks and set a threshold to obtain the count
> of rain drops. I need to do this for every chunk and get the energy over the entire 20 min recording.
>
> P.S : The 20 min recording is divided into 120 chunks with 10sec interval.
>
> I am really confused with the loop statement that does this.
>
> Can someone help me with the loops in matlab to obtain the energy over the entire 20 min recording
>
> Thanks in advance,
> Sharath
On Sat, Dec 18, 2010 at 8:26 AM, wrote:

> Dear all,
>
> I am doing research in audio processing. I have been asked to count the
> number of rain drops in a given audio recording.
>
Interesting! But if I may ask what is the point? Could you please tell
motivation behind your research problem?

> I need your precious help for the following 2 questions
>
> 1) While I was obtaining the spectrograms for the individual chunks that I
> created, I am getting the resulting spectrograms to be like thin strips and
> I had to manually zoom in to see the actual spectrogram.
> Is there any code to enlarge the vertical axis of the spectrogram to make
> it clearly visible. Your help will be much appreciated.
>
Use vertical zoom in matlab?

>
> 2) I am able to calculate the energy of the spectrogram for individual
> chunks and set a threshold to obtain the count of rain drops. I need to do
> this for every chunk and get the energy over the entire 20 min recording.
>
> P.S : The 20 min recording is divided into 120 chunks with 10sec interval.
>
> I am really confused with the loop statement that does this.
>
> see if this works -
for every chunk
for i = 1:chunksize
energy[chunkindex] = energy[chunkindex] +
sample(^2)[chunksize*(chunkindex-1) + i]
end
end
-- Pranav
*
*

However beautiful the strategy, you should occasionally look at the results.
-- Winston Churchill