Sone 134 Updated -

Bathroom fans aim for near-silence (under 1 sone = ~28 dB). Industrial fans move massive air volumes, creating unavoidable turbulence noise. 134 sones is considered unacceptably loud for residential but tolerable for short-term industrial use with PPE.

To find the phon value for 134 sones:

If a machine or room is measured at 134 sones, here is how to bring it down to a comfortable level: sone 134