I’m new to audacity, and all I want is to amplify the background fight noises in an audio file from one of my favorite television shows. In this audio file, there is dialogue, background music, background noise playing at the same time. the noise I’m interested in is the grunts and noise that the two female characters make in the scene. I don’t know how to reduce the foreground vocals without leaving behind the noise of the fight in the background. 
Audacity can’t take apart a mixed performance into individual performers, instruments or sounds. It’s a frequent request.
Koz
Thanks for telling me that, but is there a way I could amplify or reduce a certain layer of sound in a mixed audio.
When the audio was produced within the software there would have been “layers” of sound - the background music, sound effects and speech would have been produced separately, and then all of these layers would be “mixed down” into one stereo audio stream. From this point on there is only one “layer” and there is no way to “un-mix” it back to the separate layers.