This may help.
Noise reduction and optimising audio in Audacity
*N.B. Item 3 refers to adjusting the Filter Curve for specific tasks. My settings for that are to optimise MY voice.
For music, you may just go for the default settings.
1. Select a wave-free section containing noise
Effect > Noise reduction…> Get Noise Profile.
Effect > Noise reduction…> OK
2. Effect > Compressor > Settings
Threshold -18 dB
Noise floor -40 dB
Ratio 2:1
Attack Time 0.20 sec
Release “ 1.0 sec
3.* Filter curve.
4. Effect > Limiter > Limit to -3.00 dB
5. Effect > Normalize