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.
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
Oh dear!
Can anyone recommend software that will do what I want? Preferably freeware, but that may be pushing it. 
What’s it for? How exactly do you need it displayed?
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.
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/
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
I can suggest google terms …
https://encrypted.google.com/search?q=real-time+spectrogram+freeware
I’ve just tried this one on Windows Vista …
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.
Full size screen, Dotted lines at 1KHz intervals.zip (172 KB)
wow, UCL have got plenty more free audio visualization software … http://www.phon.ucl.ac.uk/resource/software.php
Nice find Trebor.
SFS/RTSPECT looks like a possibility too (works well on Windows XP). Windows Tool for Real-time Waveforms & Spectra
Yes the “SFS/RTSPECT” looks a better bet, here visualizing a recording playing in Audacity …
SFS_RTSPECT Version 2-4.zip (189 KB)
Works on Windows 7 too. To visualise a track playing in Audacity, set Windows default recording device to stereo mix or similar.
Gale
I noticed the downloads from “www.phon.ucl.ac.uk” are not working at the moment.
However I found an alternative real-time spectrogram ,
on a free oscilloscope-program called “Visual analyser” ,
[ it’s far more complex than the programs from UCL ]
![Visual Analyser 2014 [ free oscilloscope] screengrab.png](/uploads/default/original/2X/9/9056db3f03e1368cb1b64a7503ff32a1ea450dd4.png)
hi
i can’t find anymore 
Free real-time spectrogram from UCL is here … Windows Tool for Real-time Waveforms & Spectra [Windows only].
thanks a lot!