Basic Terminology
Hertz – The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI) and is defined as one cycle per second.
Bandwidth – the span of frequencies your car audio system can play most efficiently.
Your bandwidth is typically your peak frequency plus or minus 5Hz. Run a sweep on a meter to get exact data. Example: Peak is 39Hz, Bandwidth = 34-44Hz
Musical Average When playing music during the run, the average of the total score maintained through the run is the final score.
Example: You begin your run at 156 db and as the run continues it continues to lower due to loss of power over the course of the run. By the end of the run your score is now a 154 db. Your musical average final score would be about 155 db.
Peak Frequency The frequency, measured in hertz that your vehicle generates the highest decibel level.
Example: Your vehicle does a 145 DB at 39 hertz but only does a 144 or lower at other frequencies. 39 hertz would be your peak frequency.
Peak HoldPlaying tones otherwise known as burping is usually scored based on Peak Hold. This is the level at which your vehicle played the loudest and is used to determine your overall score.
Run A run is your complete attempt, from start to finish to put up a score on a meter. Some organizations allow re-runs, where you are allowed a second or third attempt on the meter.
Scratch/DQ If your vehicle is in violation of any rules or regulations or if you break a rule during your run/attempt your final score may result in a scratch or Disqualification.
SPL Meter Device used in SPL Competition. The microphone can be placed in various areas of the vehicle depending on format. It measures the sound pressure level of the vehicle. It is usually placed on the windshield near the dash referred to as a Legal or Dash Score. Other common locations are the headrest of the seat, in the kick which is the front corner of the floorboard near the door.
Sweep A series of tones played in a vast range to determine the peak frequency of the vehicle. A sweep will play a tone beginning at a low frequency and continue to higher frequencies.