Remove constant noise with Audacity

Question

Looking for ways in Audacity to reduce noise from the following audio.

• The noise sounds like a constant "shhhhh" to me
• Previously removed high-pitch noise using the low-pass filter (threshold 16khz)
• Also used the noise gate at -50db but with no effect

Two questions I consider:

• Which other algorithms can I use to reduce the noise? Which settings would you suggest for the reference audio?
• Any parameters to adjust among the filters/gates I already used to improve the results?

Feel free to denoise the track on your own to post the results later. Audacity plugins/scripts only.

Answer 1

Audacity has a noise removal plugin, which needs a sample of just the noise to be able to calculate a profile.

From Audacity Manual: Noise Reduction

Noise Reduction can reduce constant background sounds such as hum, whistle, whine, buzz, and "hiss", such as tape hiss, fan noise or FM/webcast carrier noise. It is not suitable for individual clicks and pops, or irregular background noise such as from traffic or an audience.

To use Noise Reduction, you need a region in the waveform that contains only the noise you want to reduce.

Be aware that it may be impossible to get a satisfactory removal when the noise is very loud, when the noise is variable, when the music or speech is not much louder than the noise or when the noise frequencies are very similar to those of the music or speech.

If your problem is mains hum or a high-pitched whistle, the use of a Notch Filter may help, which should be carried out before applying Noise Reduction.

There are 'smarter' algorithms out there, but none that I know of for free.