Audacity Forum

I write to inquire if audacity or any audio app has the capacity to digitally remove extraneous sounds/voices. I recall an oscilloscope had a display the allowed one to 'see' soundwave patterns. Does audacity or any other audio app have this feature?

no
not really, but expensive gear and a top engineer can do some things
yes, but not going to do what you want that way using it

Audacity has some features that may help, though it depends on what sort of sounds you are wanting to remove, and from what you are removing them.
For example if you are wanting to remove a high pitched sound from a recording you may be able to do that with simple frequency filters, though they may remove other sounds as well. If you are wanting to remove the sound of the piano from Rachmaninov's second piano concerto, then no you can't do it though there are some plug-ins that claim to be able to make a partial attempt at this (see here: http://forum.audacityteam.org/viewtopic ... 188#p83188 )

There is also a "Noise Removal" effect that can help to reduce constant low level background noise from a recording. This effect, as with most other features, has been developed and improved in Audacity 1.3.

There are also some tools available for analysing the sounds, such as "Plot Spectrum" (in the Analyze menu)