How to find the highest peaks in an audio signal?

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RamSum
RamSum 2015-2-14
回答： Greg Dionne 2015-3-24
Hi,
I have a set of audio files(.wav). Each audio file is the recording of a user typing a 8 letter word. Each letter when typed produces two sounds 1. when key is pressed, 2. when key is released. Total 16 sounds are produced for one complete typing. My question is, How can I find the highest peak of each press and release and how can I extract the timing information when a peak is occurred?
To simply my question, How to extract the timing information when a sound is produced?
How can i solve this problem. Please anyone guide me on this.
Thanks in advance.
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Star Strider
Star Strider 2015-2-16
I was hoping for the .wav file, not the image. I would have done a spectrogram of it to see if the key-press and key-release had different (and ideally repeatable) spectra, then if they did, design appropriate digital filters to detect them.
Oh, well...
RamSum
RamSum 2015-2-16
Sorry I misunderstood. Here is the audio file of the typing.

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采纳的回答

Greg Dionne
Greg Dionne 2015-3-24
Try something like this to get you started:
y = audioread('U1_S1_T1.wav')
yLeft = y(:,1);
yrmsenvLeft = sqrt(conv(yLeft.^2,ones(200,1)/200,'same'))
plot([yLeft yrmsenvLeft])

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Image Analyst
Image Analyst 2015-2-15
I know it seems obvious, but how about just thresholding??
loudElements = signal > someValue; % Logical vector.
loudIndexes = find(loudElements); % Linear indexes - actual index numbers.
Anyway, it's a start. If you need something more robust and sophisticated, you'll have to tweak it and develop something better.
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RamSum
RamSum 2015-2-17
I don't have an image processing tool box. How can i get it? Does it cost, if does how much?
Image Analyst
Image Analyst 2015-2-17
Type "ver" to see if you have it. If you want it, you'll have to contact the Mathworks.

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