I will try to relay this as best as I can. How the judging process is more complex then some one jumping in my car and just enjoying the system. First the judges have to go through some sort of training and learn the music to even become a judge. I am not sure how is process works to become a judge. Every competitor has a score sheet in their car that the judges use. Also, the judge has a CD or flash drive with the same songs to use in every ones car.
Before I get into this I believe that everyone hears things differently, some times judges can be bias to people or brands of equipment. That is the subjective part. I guess to keep this to a minimum one judge will judge all the IASCA cars, one will judge all MECA cars. Basically you can't have two judges judging the same class of cars. That would make war.
A well tuned and put together car, when listening from the drivers seat, should should like a stage. Singers voice usually centered, and instruments have places. So basically the judge knows the music so well that they would know what instrument comes in at what time, where it should be placed on the stage and how it should sound.
There are also technical tracks built into the judges media. Example to look at stage placement they use a male voice and he will say "Left" with some short 5 second musical notes played. This would be used to show how far left the sound stage is. Then the voice would say "Left Center" with same musical notes. This would show left center placement. Then "Center," "Right Center," and "Right."
They judge overall tonality, basically how good it sounds, how real it sounds. A great sounding system it not going to make your ears bleed in 20 minuets. Well because, that is not a good sounding system. I am trying to recreate, in my car, exactly how the song was recorded. The judges know how it is suppose to sound. They listen to detail, how clean and real the music sounds. They listen for the kick drum at 43 seconds that you should feel in your chest.
They judge on stage width, depth, and height. In my car depending on the track played the singer can sound like they are standing anywhere from on the hood of my car to so close to my face I can smell what they ate for lunch. That is depth. Width is how wide or narrow and height it height lol.
That is some of the basics. Here is a description in detail of the songs on the MECA disk to give you an idea.
