Engine noise to components?

I’m not professional with audio but I have still problem. I’m making simulator to computer which simulates working of hydropowerplant. I need some effects to create it more realistic. When I leave dispatch centre, which might be hundreds of kilometers away from plant, and I go to powerplant, I need some sound effects because these plants aren’t silent places. I have sound clips from real plant and main problem is separate basic hum from hydraulic pump, this plant is very old and it has mechanical turbine governor. I want that, when governor is in “stand-by-mode”, oil pump works sometimes a little bit because there is small leaks. But when governor must make work, open or close turbine, consumption of pressurized oil is much more higher and pump must work very often and long times. All frequencies of engines are quite strictly binded to 50Hz and it’s harmonics. It has very many harmonic noises. But oil pump has still a little bit another sound, so I can hear when it works or not. I want to separate basic hum and sound of pump.
Is there any ideas or plug-ins etc. to make two sounds, when only turbine and generator are working and when oil pump is feeding governor system?

We have no way to split different pumps or motors in Audacity. Once you have one show with two or more different instruments or voices or motors, you’re stuck with the mix. It’s a popular request.


Any ideas, how to repair track by removing waste components? There is also problem that generator works like fan and air flows etc. might cause problems. I can open spectrogram and take FFT-file out but is there any tool to remove components which are lower than -x dB, so I can hear and see better what I am actually searching? I think that when I find right frequency and it’s harmonics, I’m very close to finish.

I think what you are looking for is an effect called “spectral subtraction”. Audacity does not have that effect built in, but you may be able to find a plug-in to do it, otherwise you may be able to run “Reaper” (in Wine or in a virtual machine, assuming that you are using a Linux machine). There is a spectral subtraction effect available in the Cockos ReaPlugs set (see the Reaper web site for details).

I would see Noise Removal as a spectral subtraction plug-in in its purest form, that is if the subtraction is not time-dependant.

The Noise Removal effect in Audacity is more of a “spectral gate” type of effect. Closely related to “Spectral Subtraction”, except that the “subtraction” only occurs when higher level signals are absent (which is why you can sometimes here the “removed noise” reappear “through” the retained sound).

Sure, the substraction is somewhat restricted.
One possibility is to duplicate the selection with the noise profile and to normalize it.
The sensivity slider acts like an amplification too, when positive.
At any rate, it could be useful in this case because different engine states should be differentiated.