More Sound Meter fun - 10/24 AX

[Bill Behun]

(10/24 AX dB results below - some of you will be happier now)

OK folks. I as one of the AX Chairs who are responsible for "enforcing" the event club rules was approached by a long standing and very knowlegable member who was concerned we are violating our noise rules and it could lead to a number of problems if we are challenged on it and to those members who may be at an unfair advantage by not modifying their cars in certain ways that create an advantage but increase noise.

Great, now I get to deal with this as it is a legitimate issue. Am I enforcing the rules? - No. Should we? - I'd rather not but then again, why are the rules there. I live 3 miles from the stadium - I hear the Legal Drags all the time. I hear the concerts and fireworks. I never hear the car clubs autocrossing.

So, last AX we set up the analog sound meter we have. I asked how accurate is it. Well, it was accurate enough to know certain cars are clearly over the limit. See previous Sound Meter Fun thread for the "innacurate" but indicative results. I mentioned to some that I thought it only fair we get it an accurate/calibrated meter and we give time to folks to fix things if we determine this is an issue we must deal with. I will be talking to the board about this at the board meeting next week. Come to the board meeting to discuss if you like. I will follow the boards recommendations but I believe some folks will need to quiet their cars.

We purchase a good digital meter now and Lori calibrated it. She took measurements at a couple of places. (At the last AX I took the measurements as folks were flooring their cars and in high RPM down the straight after the start). This time they were taken not at the start. I'll get an agreement from the years past Noise Chairs as to where to place it. Maybe even have them place it.

The results are: (Lori only listed cars over 90 dB, not all run overages noted, just the cars) (Drivers(cars) over 92.0 in bold)

Sound meter near F3 light pole area
Rex Sampsell = 94.9/93.5/94.1/94.1/96.0
Mario Monroy = 90.7/89.9/90.3/90.6/90.3
Lisa Goetsch = 94.4/93.8
Jim Kollars = 91.1/93.0/93.5
Bob Holzinger = 93.5/90.1/94.2
Tom Comeau = 92.9/92.8/94.4/95.3/94.9/96.3
Gary Burch = 90.7/91.7/92.0
George Copelin = 91.6/90.3/94.2/90.1/90.7/92.0
Herb & Sean = 96.2/98.2/96.3/96.0/96.3, lots more
Mark Bray = 99.0/99.2/99.8/99.1/over 100/tons more 96-99.6
Morgan Trotter = 96.1/95.5
Adam Gill = 93.8/96.3/94.5/92.7/95.5/96.5
Terry Barnum = 93.1/90.0/91.3
Peter Dorey = 91.9/90.1
Tom Tweed = 91.8
Diane Weed = 92.4/93.5/90.1/94.8/90.7

Sound Meter near E3 light pole:
Mark Bray = 93.2/93.8/92.3
Margan Trotter = 94.5
Tom Comeau = 92.2/90.8/94.3/93.4
Herb & Sean = 92.5
Gary Burch = 92.4

[pdy]

Whew! Sure glad I didn't see MY name on that list!

[jenniferreinhardt]

I hope we don't open up a can of worms with this issue. I think everyone can be reminded of this at sign up, the event etc., and remain considerate of the noise, neighbors.

The 911 hasn't been measured at the Q for a while, but like Gunter, we passed at Laguna, so it is not from selfish interest that I'd hope our club can maintain a reasonable sound level, but not have to over do it.

[Bill Behun]

Paul - I heard you stuffed some steel wool in your exhaust pipe? If so it worked!!!!
I think I also heard you produced some neat sparks with it? Hmmmm, I see, hear, say nothing!!

[Kim Crosser]

Whew! Sure glad I didn't see MY name on that list!

I assume that is because you left your co-driver's number on the car during all the measurements...
Now we know what the "D" stands for - Paul "dB" Young.

[pdy]

Yeah, I'm blaming it on Mark.

For timed runs only, I jammed "Snickers" tailpipes with some wads of steel wool held in with bolts. By turn 1, he was horking up
hairballs out the butt, so that didn't make any difference by the time he went by the meter. Besides, I don't think measurements
were being made during the Blue-Group timed laps. The car was therefore the same for measurements from F3 and E3.

I did notice at F3 that the meter was backed up against a vertical tarp, which will amplify the sound, but E3 was more free-field.

Interestingly, "Snickers" also passes at Laguna Seca. Although I don't know their equipment and process, I do know where their
sound booth is - 100 feet from the track edge, which should account for 6dB less than if it was 50 feet. So if a car was measured
at 98dB at the Qurph (50 ft), it should be 92dB at Laguna Seca (assuming identical measurement techniques and equipment, etc.).

Also, this means that at 1000 ft, Snickers would only measure 73dB, which isn't much. Unfortunately, with reflections, atmosphere,
and the particular pitch of the engione noise, it might turn out to be more or less noticable in the residential areas.

I will work on something to make Snickers a bit quieter - I know it's one of the noisier cars.

[Gary Burch]

Sound meter near F3 light pole area
Rex Sampsell = 94.9/93.5/94.1/94.1/96.0
Mario Monroy = 90.7/89.9/90.3/90.6/90.3
Lisa Goetsch = 94.4/93.8
Jim Kollars = 91.1/93.0/93.5
Bob Holzinger = 93.5/90.1/94.2
Tom Comeau = 92.9/92.8/94.4/95.3/94.9/96.3
Gary Burch = 90.7/91.7/92.0
George Copelin = 91.6/90.3/94.2/90.1/90.7/92.0
Herb & Sean = 96.2/98.2/96.3/96.0/96.3, lots more
Mark Bray = 99.0/99.2/99.8/99.1/over 100/tons more 96-99.6
Morgan Trotter = 96.1/95.5
Adam Gill = 93.8/96.3/94.5/92.7/95.5/96.5
Terry Barnum = 93.1/90.0/91.3
Peter Dorey = 91.9/90.1
Tom Tweed = 91.8
Diane Weed = 92.4/93.5/90.1/94.8/90.7

Sound Meter near E3 light pole:
Mark Bray = 93.2/93.8/92.3
Margan Trotter = 94.5
Tom Comeau = 92.2/90.8/94.3/93.4
Herb & Sean = 92.5
Gary Burch = 92.4

At least I made the Top 10 in something.

[gulf911]

At least I made the Top 10 in something.

[Bill Behun]

Yup - the further away, the quieter the sound. Seems to me the real measurement should be at the stadium property lines (like we have to satisfy for some of our building projects). That's where it really counts.

Maybe at some point in time I can discretly ask the stadium.

[Kim Crosser]

Maybe at some point in time I can discretly ask the stadium.

I believe someone else posted the "let sleeping dogs lies" note, and I agree with that statement. I think we just need to resume monitoring and enforcing the given rules.

From the posted policies of the other clubs that use the stadium, and recent anecdotes from members of the SCCA and BMWCCA clubs that run there, we appear to be the only club that ISN"T actively monitoring and enforcing the limit. They all use a 93 dB(A) limit and state that it is measured 50 feet from the track, basically as Lorri ran it on Saturday. By the way, even the miniature dragsters enforce a 93 dB limit (from the NHRA Jr. Drag Races rules: "If your car is above 93 dB, you will be disqualified. The 93 dB noise level requirement at Qualcomm Stadium is dictated by the City of San Diego.").
Up to a few years ago we did monitor the noise, and DID ask people to stop/reduce the sound when it exceeded the limits.
93 dB is loud, 100 dB is really loud, and 106+ dB is ridiculously loud. If we want to continue using the Stadium (while it lasts), we need to follow the rules for using the facility.

Open Google Maps and take a look at the surroundings. There are residences 500 feet from our TRACK in the upper NW corner and 500 feet from our TRACK in the SE lot (yes, I know they are across the freeway - I would bet they can still hear some of our cars over the freeway noise).
On the other hand, the closest the dragsters get to a residence looks to be over 1000 feet. The Race Legal events also appear to be at least 1000 feet from any residences (more like 1500-2000 feet away where they start at maximum acceleration), and besides they are City sponsored and blessed by law enforcement, so any noise issues with Race Legal has no bearing on our situation.

As Paul noted, a doubling of distance has an effective 6 dB drop. So - 92 dB at 50 feet = 86 dB at 100 = 80 dB at 200 = 74 dB at 400 = 68 dB at 800 ft. Well, 74 dB isn't that horrible... (Although 70 dB is a freight train passing at 100 feet, or someone vacuuming 10 feet from you.)

But if we have two cars on the track together, they can effectively add another 3 dB. Four cars can add 6 dB. Each doubling of the sound sources can add 3 dB.
AND - in case no one noticed, we keep the track hot from 9am to closing, with 4-7 cars always on the track, producing nearly continuous sound. (The dragsters produce peak sound for what? 10-11 seconds? And then, relative quiet for quite a while between runs.)

Now, imagine four to six 100 dB cars on the track together, potentially producing 106 dB at 50 feet. 100... 94... 88 dB at 400 feet. All of a sudden, those residents 500 feet from our track are going to be hearing a lot of continous loud noise, cycling over and over for 7+ hours to obnoxious levels. Would you want to live there?

So - we can either ignore the issue until the Stadium tells us to go away for not playing nice, or we can enforce the rules like all the other car clubs AND be good neighbors to the people who live around the Stadium.

[jenniferreinhardt]

This may help visualize Paul’s description of Snickers coughing up metal hair balls. The 911 coughed ‘em up right before the sound station at Laguna Seca. So that was not the solution.

We did eventually figure the trick out.

[Mmagus]

Yeah, I'm blaming it on Mark....I will work on something to make Snickers a bit quieter - I know it's one of the noisier cars.

It is interesting that Paul and I were driving the same car, and I was the one who had the temporary steel hairball pipe treatment...yet my DB's were higher. lol I guess I must be on the throttle more through that turn than he was

Oh...wait...he beat my time. Dang your smooth driving Paul!

[John Straub]

I think it's more a liability issue...if the cars are too quiet the corner workers may not hear them coming...run out in front, WHAM and get mowed down...more noise, more noise!

Loud pipes...save lives!

John

[richard]

Forget all these numbers! At the next autocross, send someone up to the condos to listen to see how bad (or not so bad) we sound. Call in when the noise seems loud (to a couch potato) and note what cars are on the track, how many. See if we have a real problem or not. If there is but one resident of a condo who gets annoyed and is the type to complain, then we have a potential problem.

[LUCKY DAVE]

We're the only ones complaining.