This article is from the Car Audio FAQ, by Ian D. Bjorhovde (ianbjor@mobileaudio.com) with numerous contributions by others.
[HK writes:]
They are much like loud car shows: a lot of cars parked with their
hoods/doors/trunks open showing their audio systems. There are two
types of judging styles: 1) drive through - where competitors drive
their own vehicles to judging stations to be judged, and 2)
walk-arounds - where the teams of judges will walk around the event
site and judge vehicles that fit within their judging assignments.
Typically SPL is done first with the mic stand in the driver's seat and
the competitor in the passenger side adjusting only the volume.
Hearing protection must be worn. After SPL measurements are completed,
RTA measurements are performed by playing pink noise. When the volume
level is within the specified "window" around 90db-110db, the RTA judge
will signal you out, and at that point you must exit the vehicle for
the actual scoring measurements. The next area for judging should be
sound quality where two judges will sit in your car and judge the sound
quality based on IASCA's reference CD/tape. The next area is
installation judging where the competitor has 5 minutes to explain and
show the installation of his/her vehicle. It is very useful to have a
picture book/album of photos of the installation that may not be
visible to prove that items not visible do exist. When that is
completed, the competitor can park the vehicle and show spectators the
vehicle. These procedures may differ from show to show, and at the
regional/final levels they are very strict in what can and can't be
done, e.g. a judge will make sure no adjustments are made after SPL
until after sound quality judging is over, ear protection, etc.
[CD writes:]
Most involve a lot of waiting around. Thus, they are perfect for
meeting other people interested in car audio, and seeing some
installations which may give you some ideas. They're also perfect for
listening to some cars that sound a lot better and a lot worse than
your own. In IASCA competition, the cars are judged on:
* Installation Quality (187 pts possible)
- Wiring (40 pts)
- Source Units (15 pts)
- Amplifiers (25 pts)
- Speakers (25 pts)
- Other Devices (25 pts)
- Overall Creativity (30 pts)
- Attention to Show Details (20 pts)
- Security and Convenience Features (7 pts)
* Sound Quality (248 pts possible)
- Tonal Accuracy and Spectral Balance (100 pts)
- Soundstage and Ambiance (65 pts)
- Imaging (50 pts)
- Sound Linearity (30 pts)
- Ergonomics (+/- 3 pts)
- Noise Adjustment (up to -20 pts)
* Frequency Response - RTA (40 pts maximum)
* Sound Pressure Level - SPL (1 point per dB)
 
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