why does rolling down a window help?

[QuestionMan 0]

Hey, i stay true to my name

<<<. lol, but why does a sub seem louder with a window(s) down, than when they're up? I don't know if it is on a meter, or just to the ear, but shouldn't it be that if the waves are focused into a smaller space, it'd be louder? with a window down the air goes everywhere.. just don't understand.

Also, if it really is louder on a meter to have windows down, then why do the true bassheads, modified vehicles spend thousands on concreting a vehicle and making sure every crevice is sealed, when i roll down a window and it's louder. Is it just the class they're in, and the rule is windows up? Or does it actually make it louder?

Just kinda wondering as i rolled down the windows on my way home to get it louder, so i thought i'd ask, lol.

Thanks for reading,

Mitch

[audio-neon 34]

Hey, i stay true to my name

<<<. lol, but why does a sub seem louder with a window(s) down, than when they're up? I don't know if it is on a meter, or just to the ear, but shouldn't it be that if the waves are focused into a smaller space, it'd be louder? with a window down the air goes everywhere.. just don't understand.

Also, if it really is louder on a meter to have windows down, then why do the true bassheads, modified vehicles spend thousands on concreting a vehicle and making sure every crevice is sealed, when i roll down a window and it's louder. Is it just the class they're in, and the rule is windows up? Or does it actually make it louder?

Just kinda wondering as i rolled down the windows on my way home to get it louder, so i thought i'd ask, lol.

Thanks for reading,

Mitch

Every car reacts dfferently. The extreme vehicles you are talking about need a seal to reach such high pressure levels.

Some cars get louder, some don't change etc. It also depends on which window(s) are rolled down and how much they are down.

The best way to explain it is that the meter measures pressure, but sometimes the "flow" is higher and it measures that. You can easily blow a 150+dB reading in a termlab mic and be near silent, or you could have a loud car that is straining to move that same membrane in the meter just as far as if I was blowing directly on the membrane. Opening up a window can cause the air to move more.

I'm sure someone can explain it better though.

[jonbearsmt 919]

my lincoln is crazy with the back two windows. up and the front doors open.

blows like a windy day in the windy city

[Noobtastic14 0]

depending on the size of the install and movement of the air, your turning the car from a 4th order bandpass (sub box ported being chamber 1 and car sealed being chamber 2) to a 6th order bandpass (vented box on one side of the woofer and the cabin of the car being chamber 2 with "ports" as air escaping the cabin) ever see port wars? lots 'o pressure in there and that's how my feeble brain comprehends why that effect happens... although as stated different cars with different setups will react differently and playing with the different variables is the only true way to figure out how your ride will react.

-Drew

[diamond_sound 0]

in my 96 GTI I could open the sunroof and gain a few db's. Its crazy how that works.

[Yanks Fan 0]

http://www.glasswolf.net/caraudio/cabinvolume.html

Not a bad explanation there.