Fan db question...

[F/A-18 MechDood]

If you have one fan that is rated at 40db, and 2 fans that are rated at 20db each, will they have the same noise output?

Jim

[goldenbuddha]

dBA is such that 25dBA is twice as loud as 24dBA. 24dba twice as loud as 23dba etc.

But the volume of the 2 fans overall, plus the pitch, will determine if it is actually noiser or not as.

So if you ask me, the 2 20dBA fans will be less noisy.

[meese]

goldenbuddha,

Where did you come up with 25dB being twice a loud as 24dB? The threshold of hearing is considered 0dB. A whisper from 5 feet away is about 20dB. Conversational Speech is about 60dB. Loud Rock music is 120dB and a shot gun blast is 140dB.

Say you have audio output level that is 2 volts. If you double it to 4 volts thats a 6dB increase. An increase of 6dB doubles the voltage output and a 6dB decrease reduces the voltage level by 1/2. A 10dB increase is 3:1. A 20dB increase is 10:1. A 30dB increase is 30:1. A 40dB increase is 100:1. A 60dB increase is 1000:1 and an 80dB increase is 10000:1.

[311Sam]

If you were to chart the decibel levels on a graph it would be non linear, meaning it wouldnt be a straight line. The noise levels only start doubling at about 120db (i think). Meaning 120db to 121db would be twice as loud. Any noise above 150db can cause death........