The sone rating of a device, such as a range hood, is a subjective measure of the loudness of the sound it produces. The sone scale uses a group of listeners' perceived loudness of a sound as compared to one produced at 1000 hertz and 40 decibels. A sound of 3 sones has a sound the group perceives to be three times that of this base sound.
By definition, the threshold of human hearing is zero sones. Calm breathing or rustling leaves creates 0.2 sones. Normal human conversation occurs at 1 to 4 sones. Hearing damage occurs above 250 sones, and the human threshold of pain is approximately 676 sones. In selecting range hoods, it is important to balance the noise level with the CFM rating. A higher CFM rating indicates the hood has the ability to remove more cooking odors and grease from the air. Lowe's reminds consumers that units with higher CFM ratings tend produce more noise and have a higher sone rating, while quieter hoods remove less air. A 400 CFM Whirlpool range hood from Lowe's produces 7 sones of noise, almost twice the perceived loudness of a television three feet from the listener. Lower CFM hoods produce noise below the range of human hearing. The loudest of range hoods produce noise far below the levels causing damage to hearing.