Phil Allison said:
** You can use a standard SPL meter to measure any sound level possible -
all you do is calibrate the path loss at a distance.
If the SPL is say 120 dB at the point of interest with some test sound
and drops to 70 dB at a point some distance away then you have 50 dB path
loss.
If you read 130 dB SPL at that distant spot then the SPL at the
original one must be 180 dB SPL.
Get the idea ????
Hi there,
Phil, although your idea would work from a theoretical point, it
wouldn't help these guys make the measurements they need.
I first viewed this new sport/activity???? while channel surfing. Boys
and their mega toys!
Anyways the object of the exercise is to create the loudest reading on
the SPL possible. Fidelity is not part of the equation. To do that all
kinds of strange techniques are employed, including "focusing" the
sound with reflectors inside the car. Therefore, you can create a
"suite spot" where the sound pressure maxes out. Some of the tricks
used include lining the door panels with concrete to "stiffen the
reflector" There are many others possible if you let your imagination
go.
The car becomes a "sealed chamber" to contain and maximize the SPL.
And yes, they sit on the 3 inch thick lexan wind screens to hold them
in place during the "run" which only lasts a few seconds and is a
burst of a single fairly low frequency "tone".
If you were using a mechanical "attenuator", it would be close to
impossible to reasonably accurately calibrate it due to all the
non-linearity that exists at these levels. I would even question the
ability of the event sponsors to accurately measure anything.
FYI, the show stated that a Space Shuttle launch measured in the 155
DB range.
Cheers from Canada!
Bob Morgoch
