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Sound Control Standards and Procedures

The competitor shall carry sole responsibility for ensuring their vehicle complies with these Sound Control Standards and Procedures.

Vehicle sound emission is not a constant factor that can be trimmed to barely legal (in the manner of engine displacement or vehicle weight). Since sound emissions may vary significantly from morning to afternoon and day to day, competitors are advised to target any vehicle sound emission level "adjustments" to well under the penalty level to allow for variations in conditions.

The intent of the following rules is to truly make our events quieter by limiting the sound level produced by individual vehicles. Competitors are expected to use mufflers as the primary method for sound reduction. Sound measuring stations may be located on both sides of the course lane, to ensure sound output levels are below penalty levels.

Standards:

  • PPIR: Penalty level of 100db, A weighted, at the measuring point.
  • PPIR: Warning level of 97db, A weighted, at the measuring point.
  • Front Range Airport: Penalty level of 100db, A weighted, at the measuring point.
  • Front Range Airport: Warning level of 97db, A weighted, at the measuring point.
  • All other sound controlled sites: Penalty level of 93db, A weighted, at the measuring point.
  • All other sound controlled sites: Warning level of 90db, A weighted, at the measuring point.

Measurement:

  • The measuring point(s) will be established during course set up, and approved by the event chair. The course map shall be provided to the chief of sound two days before the event.
  • When possible, measurements will be taken at all event sites to provide information for competitors.
  • Measurement will be taken at a point on course where the car can be reasonably expected to be at full throttle, under load and at high RPM.
  • The measuring point will be 50 ft from the edge of the course lane using a coned gate as a reference. More than one measuring point may be established.

Sound Station(s)

  • A Sound Station will be established at the measuring point(s) on the course. At a minimum, an ANSI Type 2 sound meter with a digital readout will be used.
  • The meter will be mounted on a tripod, 3-4 feet above ground level.
  • The meter will be positioned perpendicular to the vehicles’ direction of travel.
  • The meter will be set to "A" weighting, "Slow" response.
  • When possible and practical, the Sound Station(s) will be as far away as practical from inhabited buildings (i.e., on the east side of the World Arena lot).
  • The Sound Station Operator will record the Heat #, Run #, Car # and Class and Sound Reading, on a Log developed for that purpose.
  • Sound Logs will be posted on site after each run group and on the web following the event.
  • Sound Logs will be maintained for at least one year following the current season.
  • Every car will be measured on every run (including “fun” runs).
  • The Sound Station Operator and the Grid Sound Control Worker will be equipped with a radio set to the same channel as the Corners, Grid and Control.
  • The Sound Control Grid worker will be equipped with a clipboard & notepad to record the car number and class of violators, as announced by the sound operator, for the driver’s reference when the car returns to Grid.

Violations:

  • When a vehicle equals or exceeds the warning level the sound operator will inform the Grid Sound Control Worker. The Grid Sound Control Worker will notify the driver of the offending vehicle, as soon as practical, but before the driver's next run.
  • Any run at the penalty level or over will be scored a DNF.
  • The driver will be notified of any measurement at the warning level or over
  • When a car in violation (at the penalty level or over) returns to grid, the Grid Sound Control Worker will notify the driver of the car’s measured sound level. The driver will be given the opportunity for a "mechanical delay" to attempt to reduce the vehicle’s sound level.  If, in the judgment of the Grid Sound Control Worker, the driver has attempted a viable remedy, he will authorize a "second chance run."  If the driver(s) declines any "repair" action, or the "repair" is deemed inadequate or inappropriate by the Grid Sound Control Worker, the driver(s) will forfeit all subsequent runs in that vehicle. The Grid Sound Control Worker may offer advice to competitors.  However, this advice shall in no manner be construed to imply that said suggested corrective action(s) absolves the competitor from complying with these Sound Control Standards and Procedures. This advice, if followed, is not a guarantee that the competitor will be able to comply with the sound restriction. It is only advice, suggesting methods that may reduce the sound level of the vehicle.
  • If the vehicle equals or exceeds the penalty level on the “second chance” run, the vehicle may be given a “final chance” run if the vehicle meets all the requirements of the previous paragraph (second chance run).
  • If the vehicle equals or exceeds the penalty level on the "final chance” run, all subsequent runs by that vehicle, if any, are forfeited.
  • Drivers may appeal the decision of the Grid Sound Control Worker to the Event Chair.
  • Temporary exhaust extensions (turn-downs, elbows, etc.) are permitted.  If the extension redirects the exhaust flow exiting the exhaust system, and the direction of the extension can be changed, the direction of the exhaust flow must be directed toward the ground and not to either side of the car. The acceptability of a temporary exhaust extension shall be at the discretion of the Grid Sound Control Worker, Sound Chief or Event Chair. Elbows and Turn-downs are a mildly effective method of sound reduction if pointed directly towards the ground, but they shall not be misused in order to direct exhaust flow away from the sound station.
  • Any car that is DNF’ed for a sound violation on any run in three consecutive events in which it competes will not be allowed to compete at RM-Solo sound-controlled venues for the remainder of the calendar year. Competitors are expected to make substantive modifications to their cars in response to sound violations, such that multiple violations are unlikely.
  • Competitors are reminded that an Event Chair has the option of excluding any vehicle at his or her discretion. If nothing has been done to lower the sound level of a vehicle after two events in which the car was DNF’ed for sound violations, the Event Chairs of the subsequent events would have more than enough justification to prohibit the entry of the offending vehicle.