John Sayers' Recording Studio Design Forum Archive

forgive me, this question sounds crazy, but i had to ask.

Isn't -6db of sound tranmission loss the same as lowering the volume of a speaker by -6db???

I extracted a commerical song into Sound forge:
created a few markers at various places in the sound file:
highlighted every other section divided by the markers:
then reduced them by -6db.

so that I can play the file beginning to end and hear the differences a -6db down will make. I hit play, set the volume at 100db on the sound meter, closed all doors to the studio, then walked outside to see what the differences would sound like. and woo.......-6d makes a big difference with what's getting to the outside of the studio.

Right now I'm getting about 45db or so and may try to get a bit more.

nukmusic wrote:. . . woo.......-6d makes a big difference with what's getting to the outside of the studio. . .

Thanks for posting this. It's nice to have narrative descriptions of this stuff so that we know the reality behind all the math.

I have known for some time that decibels are a lot like the Richter scale, where the difference between, say, a 7.0 quake is twice as severe as a 6.0 quake. Hey, I'm in California -- we think about these things once in a while!

Anyway, I've also read that a 1 to 2 decibel reduction is so neglible so as to not be noticed, but that a 3 decibel reduction can be noticed. So, I would have to assume that a six decibel reduction would be noticed twice as much.

cool. any other ideas?

It's not the same; for one thing, speaker efficiency differs from speaker to speaker - you know the spec that says something like "92 dB, 1 watt, 1 meter"?

SPL meters meaures ACOUSTIC watts, while proggies like Sound Forge (IIRC) measure dBV or dBU - these are both VOLTAGE levels, not POWER levels, and even POWER levels are still electrical, not ACOUSTIC.

Without spending a lot of time I don't have right now, the simplest way to check what's going on is to measure INSIDE the room at 100 dB, then see what the SPL drops to INSIDE the room when your -6 dB passages play; that's the REAL acoustic difference, regardless of what your Sound Forge meters say... Steve