Tony is correct that the 2 sound limits (Devens/NHIS) are almost identical.
90 dBA at 75 feet is 93.52 dBA at 50 feet ( NHIS requires 94 dBA at 50
feet).
dBA varies as 20 log the ratio of the distances.
Be careful about absolute distance, reflections from hard surfaces, and
foilage when you check your car with a meter at home. Foilage and soft
surfaces will decrease the sound level more at the same distance.
Chuck
Here are the NER Solo sound rules from our web site:
* All vehicles participating in NER-SCCA Solo events will be
required to meet a sound limit of 90dBA measured at 75' at Devens and
94dBA at 50 at NHIS. This may be measured from any side of the
vehicle at any time and includes such noise sources as intake noise
and tire squeal. Note that these two sound levels are virtually
equivalent. Vehicles which meet one limit should be legal for the other.
* Vehicles such as those in FM and CM which have a GCR-mandated
maximum length may exceed that length for the purposes of installing
an alternate muffler or exhaust system. The additional length may
serve no other purpose.
* After the first violation, the competitor will be required to
demonstrate that an effort has been made to reduce sound levels
before being allowed to make a second run. This determination will be
made by the event chair or a designee. If the second run is still in
excess of the allowed sound limit, the competitor will not be allowed
to make any additional runs at that event and the competitor will be
required to again demonstrate that improvements have been made before
being allowed to participate at further events.
* Event staff reserves the right to red-flag a car in excess of
sound limits and no re-run will be given.
* These sound regulations will apply at both NHIS and Devens.
Regards,
Tony Jagodnik
NER SoloII FM 6 '87 KBS Mk3 F440
[EMAIL PROTECTED]
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