Quote:
Originally Posted by Jhop
Yes yay for logs! But again I have to disagree.
To address your first comment, I was simply correcting where you state that power and volume are interchangeable which thy are not ie below:
I found a good reference talking about the interference of two wave sources which is exactly what we are dealing with (constructive interference of two acoustic wave sources to produce a louder sound.
http://bolvan.ph.utexas.edu/~vadim/C...terference.pdf
Equations 4 and 5 are important, and assuming the waveform produced by both pairs of tones are the same (same amplitude and phase) you can see all delta phi's are zero and for the perfect exactly constuctive interference you get double the amplitude (related directly to spl) and quadruple the power equaling a dB increase of 6dB.
Can't we just be friends??
Edit: and doubling the sources in this case is equal to two sources emitting the same amplitude/phase/power acoustic waves and how they constructively interfere to create a louder sound is what we are interested in

No, I totally agree
. I merely put volume next to power as its easy to explain in lamens terms for those that don't understand what you and I are talking about
.
Total energy remains unchanged because higher kinetic energy at the mean position converts into higher potential energy at the extreme points such that their sum remains constant.
Hella rates their horns at 118db summed, so if we use this pair as a base (2), and double that base, we then use the log
10 * log10 (2) = x to calculate the change in volume. If hella rated their horns at 118db
individually than you would be correct. Reversing our formula, we could postulate that a single horn would produce 115db  a quadruple of our source would result in a 6db gain, for a total of 4 horns. I think that is where you were getting off.
This is a pretty good link that explains it:
http://www.osha.gov/dts/osta/otm/noi...opagation.html