Quote:
Originally Posted by Finnegan
Rule in California is 95db using According to SAE JS1169. What that means is hard to say as I can't find the actual rules anywhere, and it's 60 bucks to buy it from SAE. Some say it's measured 20" from the exhaust, some say behind, some say perpendicular (makes more sense), at halfway through the engine's rev range. But there is a set procedure.
When the law was first put in place (2002) lots of tickets were written, and almost all were dismissed upon actual measurement. It's still at an officer's discretion to write a ticket, and most were finding issues that didn't exist. Just like front plates, tint, and other things, it depends on where you live and other factors as to whether this would be an issue--it's more of a hassle/harassment factor than anything else.
Our recents tests, with a drive by @20 feet, found stock at WOT was measured at 87db My Diablos registered 90db and the RPIs 95db.
The testing procedure sounds, pun intended, rather flawed. How do they test at 1 meter on a driveby? How much throttle, and to what rev range, etc. The parameters seem a bit subject to quite a few variables which could mean 5-10db variances, unlike the SAE method, unless I'm misunderstanding the measurement methods.
What was behind this move? I can see keeping levels somewhat reasonable, but it seems rather severe in terms of expected levels if stock--which is really quiet--almost fails. |
From what I know, the device in use in Calgary captures stereo sound and video tracks along with taking the measurement. The value is normalised to a sound pressure value at one metre distance, but I don't know if they can manually or automatically adjust the distance (it could easily be measured as the vehicle passes by).
The bylaw is drafted in such a way as to ignore the number of revs or throttle opening, they are basically saying it is up to the user to keep the noise down, if you drive a vehicle with a loud exhaust gently yoiu may be quieter than a vehicle with a quiet exhaust that is driven aggressively. The police officer who gave me my result said "you'll be fine as long as you don't scream away from stop signs" (but I do get a waiver anyway, as I haven't modified the exhaust).
It remains to be seen if the fines will stand up in court, I'm sure there will be many Harley riders fighting it. The bylaw was inspired by the noise of open pipe Harleys roaming around the city on hot summer evenings when people are outside or have their house windows open. During the "noise clinic" the police held today, more than half of the vehicles there were Harlerys. I talked to a Harley rider while waiting at traffic lights after leaving the event, he also registered 93dB, but didn't pass the measurement device at full throttle or high revs.