Ceiling Exhaust Fan -How loud is .5 sones?

I belive Home Depot has a display where you can hear various fans.

Your question is difficult to answer as the rating system is based on a number of factors, much like trying to calculate savings from insulation in an attic :^).

From the internet, a sone is a unit of perceived loudness after a proposal of Stanley Smith. Loudness is a subjective measure of the sound pressure. One sone is equivalent to 40 phons, which is defined as the loudness of a 1 kHz tone at 40 dBSPL.

The volume of a sound is a subjective perception. To "measure" loudness the volume of a 1,000 hertz reference tone is adjusted until it is perceived by listeners to be equally as loud as the sound being "measured."

The loudness level, in phons, of the sound is then equal to the sound pressure level, in decibels.

Short answer, (In my opinion), If the fan is near you and you have a very quiet room you will hear it.

"I belive Home Depot has a display where you can hear various fans."

Thanks Jd,
It's great if they have many of them side-by-side for testing and I'd be greatly delightful & will keep that in mind.
However, unlike my WELL TREATED HT room, the noise inside home depot is tramendously loud. It's like audition new pair of speakers sharing a room with a jet engine running. Lol.

"Short answer, (In my opinion), If the fan is near you and you have a very quiet room you will hear it."

Thanks Albert,
If any1 can confirm .3 or .5 sones is as noisy as the back of the computer fan, that'd be ecellent and I can live with that.

Thanks Albert,
If any1 can confirm .3 or .5 sones is as noisy as the back of the computer fan, that'd be excellent and I can live with that.

Computer fans vary a lot, and the distance your ear is from that fan is also a factor. How far from this fan will your ears be?

What else is going on the room that might mask (compete) with that noise?