# question about how decibles are measured

Discussion in 'OT Technology' started by Biomechanoid, May 7, 2004.

1. ### BiomechanoidNew Member

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or, why is it that the exact same system that was in my "spacious" civic, literally sounds twice as loud when transplanted into my small ranger truck?

I'd assume it's because I'm literally sitting twice as close to all the speakers- now I'm almost doubling the net wattage with the system that's currently being built (putting 1200 watts through 2 12" subs as opposed to 720 through two cheap 12", putting 85watts RMS as opposed to 40watts RMS through the midrange/tweeters).

will this mean to my ears that at max volume I'd be percieving twice the volume with the new system over the old system? also, how would I go about getting my decible rating measured short of going to a comp? (BTW... I'm more set up for soung quality than SPL, but I'm just curious as to what kind of damage I'll be doing to my ears)

and how exactly ARE decibles measured? I know there's a microphone placement part of it, but does the size of the interior of the vehicle effect it too? or would that just be relative to the fact that the speakers are closer to the microphone in a smaller cab than in a larger one?

2. ### On_OneGuest

Doubling power with all things being equal will give you a theoretical increase of +3 dB. While +3dB is a doubling of acoustical energy it is not percieved as twice as loud. The human ear percieves a doubling loudness at +10dB. While a 3dB increase is noticible it will not be twice as loud.

3. ### On_OneGuest

The difference in cabin size and you being closer to the driver are the main reason why it is louder.