I have an audio file that contains multiple sound events of a fraction of a second that appear identical when listening in headphones.
I would like to be able to visually compare two samples so that I can see if the graphic representation is really identical.
Based on some Google searches, the comparison technique should be called acoustic fingerprinting.
Is there any way to do this with Audacity ?
One thing you could do is switch the timeline to Spectrogram View with the menu on the left. Capture the screen and then compare the capture to the live version of the second one.
If the two sounds are in compressed format such as MP3, then they may already be different just from the MP3 compression distortion. This is the same reason some sound cancellation tricks fail. You can do it, just not in MP3.
What’s the job? Why do you need to compare them? There may be other ways to do this once we find out what the job is.
Koz
The file is recorded using mp3 compression but I can even record in .wav 24 bit 96khz.
I would like to point out that I have no experience with the forensic investigation world and I do not know if what I have in mind is possible.
My initial request arises from the fact that I would try to understand if there is a way to distinguish between a sound produced by a wall structure due to thermal expansion of concrete, brick or reinforcement iron, from a sound generated by an electromechanical device that is part of facilities present in the building structure.
I expect that the noise produced by the expansion of materials forming part of a building will have some kind of variability, which should not be present in a repetitive sound event generated by an electromechanical device.
Graphic comparison of audio samples could be useful for the purpose.
Audacity has a number of ways to visualize sound.
Most obviously is the waveform (the blue wiggly shape on the track) which can be viewed at different zoom levels:
http://manual.audacityteam.org/man/audacity_waveform.html
http://manual.audacityteam.org/man/zooming.html
Then there’s the spectrogram track view :
http://manual.audacityteam.org/man/spectrogram_view.html
and “Plot Spectrum”:
http://manual.audacityteam.org/man/plot_spectrum.html
forensic investigation world
That’s the Phrase that Pays. Audacity can’t do forensic analysis. We’re not traceable to any characteristic standard and we’re not stable enough over time to be useful. Or more accurately, Audacity is stable, but all the equipment and devices around Audacity aren’t. Audacity gets its work from the computer, not from the microphone.
It 's the same reason we can’t help with neighbor noise, dog barking and loud sound issues. You can look at the displays for your own entertainment, but it sounds like you want to take it further than that.
Koz
Do you think that this is a limitation of software in general or should I look for a program better tailored for my specific needs ?
I’d suggest that you start with Audacity. If nothing else, you will learn a lot about some basic tools of audio visualization.
Another (free) program you could try is Sonic Visualizer http://www.sonicvisualiser.org/
Beyond that you’re probably looking at highly specialised (and very expensive) audio forensic software.
Thanks, I will follow your suggestion.