Audio noise reduction: how does audacity compare to other options? Audacity's noise reduction filter is pretty good.  Before I use it, though, I want to know if I'm missing out on any fundamentally different approaches that may work better.

I have some recordings of my brother singing and playing piano.  It's pretty good as-is, but there's noticeable white noise.  There's also a 60Hz signal that's audible (but not really objectionable) during quieter portions of the recording.  Audacity does a pretty good job of getting rid of them.  So I'll almost certainly just use that, esp. since very recent audacity changes apparently have improved the noise-reduction filter.  (or maybe just the config UI?  I didn't look at the diffs).

The comments at the start of the file describes the design pretty well, and what the settings sliders mean (esp. the frequency smoothing was a mystery until I thought to check the source, and found it had a great comment describing the design.)

It gets a profile of the kind of noise you want to remove from a clip of only noise.  For the main pass, it FFTs the input, and silences every frequency bin that is below a threshold.  So it's a bandpass filter that adapts to only let through frequencies with signals above the noise level for that bin.  (Thresholds established from the noise profile.)

So my question is, are there other designs for noise filters that work any better?  Mostly out of curiosity, since audacity works very well for my application.  (noise energy distributed over a wide frequency range, signal I want to keep made up of fairly narrow frequencies.)
I am the author of the code you are reading.  It appears you were an alpha user of Audacity 2.1.0 in advance of its release, which was only days ago.  You have a version of the noise reduction effect with many experimental optional controls exposed to the user that are not in the release version.

You may be interested in what I wrote here about the inadequacies of the previous version of the effect that I tried to remedy with this rewrite.  But the overall procedure remains unchanged.

http://wiki.audacityteam.org/wiki/Proposal_Noise_Removal#Critique_of_current_Audacity_Noise_Removal_by_Paul_Licameli