The sones rating applies to any appliance with an exhaust fan and is a measurement of how sound is perceived by the listener. The lower the rating, the quieter the appliance, meaining it won't interfere with conversation or any other household activities. One sone is equivalent to the quiet humming of a refrigerator, whereas a four-sone rating would interfere with conversation among a group of people standing close by. If having a quiet appliance is a top priority, you should choose a microwave or range hood with a low sones rating.
Appliances with Sones Ratings