ASK THE MXPERTS: (10/08/09)

On Oct 8, 2009

Dear MXA,
Why is the AMA dragging its feet on sound standards? I have been racing for years and the bikes are not getting any quieter. The AMA needs to step up to the plate while we still have places to ride.

    There is no doubt that the AMA method of measuring motorcycle decibels is seriously flawed, but given the limited scope of their understanding of sound, the AMA has made a journeyman’s effort to reduce decibels (dB). In 2006 the AMA mandated decibel level was 102dB. Today it is 94dB. It should be noted that each three decibel increment affects a 50 percent change in sound pressure levels. Thus, a 3dB drop reduces sound exposure by 50 percent, while a 6dB drop reduces exposure by 75 percent. It is obvious that motocross bike have not become 75 percent quieter since 2006, but that is because the AMA tests mufflers at an rpm level that is close to idle speed. Until they start testing mufflers at max rpm, they are wasting their time.

   Current sound testing procedures are a total waste of time for the sport, the teams and the riders. When the AMA tests 450’s at 4500 rpm and 250’s at 5000 rpm they are just blowing smoke. This is fake sound testing that makes the world quieter when the bikes are at idle, but does very little to change the overall sound pattern at speed.

   As always, there are talks and plan afoot to do something about the noise issue, but, as always, no one seems to know what those things are. And, if they aren’t written in stone very soon, the teams and manufacturers will lose another year or more before they can comply.