Density sensors employ a small DC (direct current) fan that emits less than 30 dB of noise while in operation. 30 dB is the typical noise level of a library and is even lower than most desktop computers. However, because of the speed at which this fan spins while operating, it emits a sound at a frequency that can be perceptible in quiet areas, such as conference rooms where no one else is speaking.
 
This is the typical operation of the product and is no cause for concern. However, if there are other noises associated with this fan that are not associated with a consistent hum and seem more sporadic and varying in pitch, it can possibly be an issue needing attention. Please consult directly with your Density representative if you have any concerns regarding the fan.

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