I recorded an event in a hotel this week and am now noticing a faint but really annoying chirping sound caused by what sounds like an air conditioner in the room.
Air conditioning is 'usually' fairly simple to get rid of, by using noise reduction in soundforge. (IIRC SF even came with an example of removing air-conditioning noise as a tutorial example ages ago)
iZotopes' RX would also do the trick.
As I mentioned. Sony's noise reduction will do it (or should do).. iZotopes Rx will do it (or should do). You can try the ol' phase trick too if you like,
Basically - stereo waveform. Take one channel, invert it, then combine the 2 channels. Results = centre (in phase) channel cancellation. If your audio source is mono, then this option will not work. (that's for vocals).
similar principle here. Take a snippet of "pure noise", invert, and then use that to cancel out the noise from the rest of the audio. But I really would investigate options a) or b)
Please define "chirping". (Like a bird? )
If this is a constant "din" type noise, noise reduction plugs can attenuate it. Otherwise you will need a spectral type of NR process. (and a lot of time)