Is it audible?
Most likely not, but you have to try it to find out. If not, then it will be like the <0.1% THD+N thing, you may still hear it because you know it's there, not because you can actually hear it.
It also depends on the combined effects of more than one thing. I can demo all day long that my Halo A21 will hum (a little high pitch than the typical 60-180 Hz hum) loudly every time I had a portable humidifier running and plugged into a nearby outlet, but on one speed setting only. That tells me the noise is due to harmonic resonance. Any other amps I plugged into the same outlet would not make such noise under the same condition, but the A21 would do it 100% of the time.
My point is, if you can avoid it, don't do it. Any kind of motors will produce noise in the power system, especially the variable speed types. They also typically draw an initial current inrush of up to 20X (around 2-10X most of the time)rated current, or higher depending on the type of motors (much lower for the VFD types) and the point on wave when it is turned on and the remnant magnetic flux in the motor.
