Uses For Audacity

Can Audacity be used for signal processing, or only for simple recording/mixing/mastering? Is there a plugin that permits Audacity to record streaming audio/signals ?

Yes, but not “real-time” processing. The signal needs to be recorded or imported, then processed.

No. Audacity records whatever the sound system sends to it. It is the job of the sound system to send the signal that is to be recorded.
On Linux and most older Windows computers the sound system can be set up to send streaming audio as the recording input signal (often called “Stereo Mix” on Windows machines). On some newer Windows computers and on Mac OS X it may be necessary to use third party software to route streaming audio to the recording input. One example of a Windows application for doing this is “Total Recorder”, and for Mac OS X there is “Sound Flower” (there are others).

See here for more information: http://manual.audacityteam.org/man/Tutorial_-_Recording_audio_playing_on_the_computer

thankyou very much for your answers. i don’t seem to have configurable windows options to record streaming input, other than from the mic. thanks though i’ll have to read more about audacities features to see how it can be of use to me.