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Filtering frequency during recording

Posted: Sat Jun 09, 2012 9:30 pm
by Asker24
I am new to this, and using Audacity 2.0.0. with Windows 7 Home Premium. I would like to record only sounds of a limited frequency (~8 to 10kHz), and have found out how to do that with a playback (from the Effect menu and Equalization), but I need to pick up noises at this specific frequency range and display them in real time.

Re: Filtering frequency during recording

Posted: Sat Jun 09, 2012 11:26 pm
by kozikowski
Audacity doesn't do anything in real time past record, play, and some timer functions. No filtering and no effects. It's a future product request.
Koz

Re: Filtering frequency during recording

Posted: Sat Jun 09, 2012 11:48 pm
by Asker24
Oh dear!

Re: Filtering frequency during recording

Posted: Mon Jun 11, 2012 1:56 pm
by Asker24
Can anyone recommend software that will do what I want? Preferably freeware, but that may be pushing it. :)

Re: Filtering frequency during recording

Posted: Mon Jun 11, 2012 5:36 pm
by steve
What's it for? How exactly do you need it displayed?

Re: Filtering frequency during recording

Posted: Mon Jun 11, 2012 10:49 pm
by Asker24
>>>I am new to this, and using Audacity 2.0.0. with Windows 7 Home Premium. I would like to record only sounds of a limited frequency (~8 to 10kHz), and have found out how to do that with a playback (from the Effect menu and Equalization), but I need to pick up noises at this specific frequency range and display them in real time.<<<

I am deaf and cannot hear the bean-cracking sounds very well during coffee-roasting. These are the triggers for changing temperature of the roast and knowing when to shut it down. From playing back other roaster's recordings I know the frequency in which I am interested. The set up is a mike plus PC notebook, at the moment with Audacity. A mono display will do the trick and this should be displayable at about one second per half inch. Filtering out the other frequencies is the objective, to provide clarity/certainty. The roaster that I use (Gene Cafe) has a predictable "clang" once every six seconds, and this needs to be distinguished from the bean-cracking noises that are not unlike popcorn popping at one phase and Rice Krispies popping at another.

Re: Filtering frequency during recording

Posted: Mon Jun 11, 2012 11:46 pm
by steve
How ingenious.
As Koz wrote, Audacity does not do real time processing so I doubt that it will be much use for your application.
It may be worth looking at Wavosaur which I think does have real time processing ability http://www.wavosaur.com/

A possible alternative to filtering the input and looking at the amplitude, would be a real time spectrum plot, so it may be worth looking to see if Wavosaur will support Voxengo SPAN http://www.voxengo.com/product/span/

Re: Filtering frequency during recording

Posted: Tue Jun 12, 2012 4:10 am
by kozikowski
The early QuickTime system had a simple moving spectrum bar graph that jumped as audio was playing, but I think they peeled that off in the latest versions. Koz

Re: Filtering frequency during recording

Posted: Tue Jun 12, 2012 6:49 pm
by Trebor
I can suggest google terms ...

https://encrypted.google.com/search?q=r ... m+freeware


I've just tried this one on Windows Vista ...
real-time spectrogram (''rtgram'').png
real-time spectrogram (''rtgram'').png (67.05 KiB) Viewed 1733 times
http://www.phon.ucl.ac.uk/resource/sfs/rtgram/ (it records the sound too)
The maximum time interval which can be displayed on the screen is only 15 seconds,
which may be too short for your coffee experiment.

Re: Filtering frequency during recording

Posted: Tue Jun 12, 2012 7:51 pm
by Trebor
wow, UCL have got plenty more free audio visualization software ... http://www.phon.ucl.ac.uk/resource/software.php