I am not in the US, but I do have a three-speed ceiling fan – I do believe it is a single-phase induction motor with three-part windings, with a direction switch – with a very wide (diameter almost 300mm) motor section.
I originally bought three of them over a decade ago, and I'm extremely happy with them still: the motor is absolutely silent. I appreciate quiet. It matters to me more than the energy consumption, so much so that I'm willing to pay for double the power use for a silent motor. I do pay about 0.30 €/kWh for my electrical energy right now (including power, transmission, and taxes).
I only use the fan during the summer months, and then mostly at its lowest setting (about 50 RPM) to circulate the air. The only noise it generates is the slight white noise from air drag at the blades; otherwise I could not use it in the same room I sleep in. I have swapped out USB wall warts and power supplies that use too low (<25 kHz or so) switching frequency for me, causing a sound I can perceive when trying to fall asleep. (It is also the reason why I've always built my own computer enclosures, as I do need essentially silent operation if I intend to sleep in the same room.)
BLDC motors
can be absolutely silent, but I wonder if any manufacturer bothers to make one that
is silent at very low RPMs?
When PWM-controlled 12V PC fans first came to market, they had a similar problem, too. They do have a separate 12V power input, and their PWM input is standardized to use a 21-28 kHz PWM frequency – 25 kHz nominal – with minimum RPMs typically on the order of 300 RPM. Thus, it is not
difficult to filter the effects of the PWM out within the human hearing range (plus a bit above for freaks like myself), it's just that 'cost optimization' tends to mean such niceties are omitted.
(When they tried to make compact fluorescent flickering horrible-CRI lights the standard here, I refused. I only moved from glowing tungsten to LEDs when I found ones that did not irritate my vision even when I was tired. I'm actually quite happy fluorescent tubes are being phased out.)
I fear this is just another race to the bottom, to the lowest common denominator. Most people will end up with buzzing ultrasound generator fans, with only the very rich using custom-made "illegal" silent devices –– because when you cannot get any richer, you can still make others poorer, and that way make-believe yourself better than others.
