IMPBA noise rule & dB meters

[dr gary turner]

Don, the problem I see with stationary testing is that the motor may be rich and may not reach full rpm. I had put some thought into this and it makes since that a motor that is not loaded will not be working as hard a make as much noise.

Also with the Evansville pond being rock throwing distance to the interstate the back ground noise changes alot. I reaaly believe the board of IMPBA SHOULD GIVE SOME DISCTETION TO THE HOST CLUB until we learn more about qll of this.

Allen

Yes Allen that is a point to consider but if you give the CD discretionary power he can have the boat tested as soon as it's brought in & not "tweaked down". As a CD or race official I for one would have no problem telling someone on the test stand to lean it up & let it rev if you want to keep racing.

And the interstate being there is not part of the peak noise level. A dB meter knows only one thing, what the loudest sound is/was. So unless that interstate measured out at over 92dB with no boats running it's not a factor. I think the two biggest factors were a totally unforgiving site offering zero sound bleed off & meter calibration issues. Like Dave Marles said 92dB is actually still loud. :blink:

Don, the problem I see with stationary testing is that the motor may be rich and may not reach full rpm. I had put some thought into this and it makes since that a motor that is not loaded will not be working as hard a make as much noise.

Also with the Evansville pond being rock throwing distance to the interstate the back ground noise changes alot. I reaaly believe the board of IMPBA SHOULD GIVE SOME DISCTETION TO THE HOST CLUB until we learn more about qll of this.

Allen

Yes Allen that is a point to consider but if you give the CD discretionary power he can have the boat tested as soon as it's brought in & not "tweaked down". As a CD or race official I for one would have no problem telling someone on the test stand to lean it up & let it rev if you want to keep racing.

And the interstate being there is not part of the peak noise level. A dB meter knows only one thing, what the loudest sound is/was. So unless that interstate measured out at over 92dB with no boats running it's not a factor. I think the two biggest factors were a totally unforgiving site offering zero sound bleed off & meter calibration issues. Like Dave Marles said 92dB is actually still loud. :blink:

Don, I think you should brush up on the physics of sound. Sound is additive. There is a formula to calculate the additive funtion. If there are two boats making 90db it does not add up to 180 db but it is more than 90 db. I put the formula in my article in the Rooster Tail. It was quoted from an established text book on the physics of sound. There are too many comments being made as if it was gospel without the science and physics support. A twin is actual at a disadvantage because of the additive affect of two motors. Doc

 

[Don Ferrette]

...... A twin is actual at a disadvantage because of the additive affect of two motors. Doc

Actually in some instances it has been opposite of what you suggest, that the twins can & do come in less than a single due to the 2 motors having a slight cancelling effect on each other. I've seen this myself & I was told others saw this happen @ the Internats where singles were louder than the same motor/pipe combo in a twin. Plus just because there is a "formula" doesn't mean it is gospel either. In over three years of testing I've yet to see a boat's dB reading that got louder because it was with a pack of boats on the water vs. alone. Theories & formulas are a great tool but you & I both know that they also can get disproven too. I hear what you're suggesting & that's cool but I'm going on what I've seen thru physical hands on testing.

 

[dave roach]

Put the quiet pipes on and use them the way they come from the factory and quit drilling out the stingers.

Dave Roach

 

[Piston1]

Don, with all due respect your previous statement makes no sense whatsoever, please explain.

 

[Joe_Knesek]

...... A twin is actual at a disadvantage because of the additive affect of two motors. Doc

Actually in some instances it has been opposite of what you suggest, that the twins can & do come in less than a single due to the 2 motors having a slight cancelling effect on each other. I've seen this myself & I was told others saw this happen @ the Internats where singles were louder than the same motor/pipe combo in a twin. Plus just because there is a "formula" doesn't mean it is gospel either. In over three years of testing I've yet to see a boat's dB reading that got louder because it was with a pack of boats on the water vs. alone. Theories & formulas are a great tool but you & I both know that they also can get disproven too. I hear what you're suggesting & that's cool but I'm going on what I've seen thru physical hands on testing.

From the National Institute of Standards web site: "Example: A turbine located at 200 m distance with a source level of 100 dB(A) will give a listener a sound level of 42 dB(A), as we learned in the table before this one. Another turbine 160 m away with the same source level will give a sound level of 44 dB(A) on the same spot. The total sound level experienced from the two turbines will be 46.1 dB(A), according to the table above.

Two identical sound levels added up will give a sound level +3 dB(A) higher. Four turbines will give a sound level 6 dB(A) higher. 10 turbines will give a level 10 dB(A) higher."

 

[Piston1]

Knesek, I agree. Like Doc said, there is a additive effect. I think Ferrette is confusing the lower db level that a nicely tuned twin produces versus the higher db that an unsychronized twin detonating, cackling, and cracking produces. The 180 cancelling effect that Ferrette refers to can not be achieved with the systems we run.

 

[Don Ferrette]

Knesek, I agree. Like Doc said, there is a additive effect. I think Ferrette is confusing the lower db level that a nicely tuned twin produces versus the higher db that an unsychronized twin detonating, cackling, and cracking produces. The 180 cancelling effect that Ferrette refers to can not be achieved with the systems we run.

Isn't the objective with a twin to have the motors properly synched?

The cancelling effect was seen there at the Internats, a couple people witnessed this, a single was louder than the same engine/pipe combo that was in a twin. Jose' you just contradicted yourself referring to the lower dB output of a nicely tuned twin then say it can't be achieved with the systems we run. Well maybe it's time to change the system......... <_<

I'm fully aware of the charts & standards, just haven't really seen this played out in our situations. For example a boat that reads 92dB in a group running still basically reads 92 when it goes by the meter alone, I've seen this happen many times. And FWIW the example given of sound of turbines 160 & 200 meters away, that's 524 & 656 feet folks, we're measuring at 50-100 feet, let's compare apples to apples. This is another reason why I hope a form of static on the beach testing can be done. Come up with a number that would equate to 92dB on the water @ 50 feet & that's the mark. No more additive gain this or unforgiving site that, when you testing a set distance drydock. Meter gets placed x number of feet from boat, pull the trigger, take a reading.

If we put 1/2 the energy into working on a solution as bitchin' about it we'd already be under the limit. And once meters are calibrated so everyone is on the same page then we will have something to go on. Until then nothing further can be done to move forward on this. :huh:

 

[Joe_Knesek]

And FWIW the example given of sound of turbines 160 & 200 meters away, that's 524 & 656 feet folks, we're measuring at 50-100 feet, let's compare apples to apples.

Don, it's an example of how to measure multiple sources using the distance tables. If you go to the site and read up on it maybe you would realize my point is that it contradicts your "expert" opinion that multiple sources does not make a difference in db reading. If you are correct then I guess my ears lie to me when I go to the Bristol cup race and find the cars to be loader than they are at Martinsville.

They must be drilling out the stingers when they go to Bristol.

 

[Don Ferrette]

They must be drilling out the stingers when they go to Bristol.

That's funny Joe. :lol:

And BTW, I never ever claimed to be an expert, don't put words in my mouth. :angry:

All I'm going on is many hours of what the dB meter tells me in straight up hands on testing.

I still think the on the beach bench test is the way to go. If we can come up with a number that equates to 92dB @ 50 feet on the water then all this gets real easy. Hmmm, weren't you the first one to mention that approach here.........

 

[piper_chuck]

I still think the on the beach bench test is the way to go. If we can come up with a number that equates to 92dB @ 50 feet on the water then all this gets real easy. Hmmm, weren't you the first one to mention that approach here.........

Let's take a step back and think about the objective of the noise limits for a second. Unless I'm confused, we're trying to quiet the boats down so people near the pond don't complain about the noise, right? If this is truely the case, then perhaps we should focus less on a rule that provides such a precise method of measurement.

As a straw man, maybe we should just have a rule that says your boat must be below some number of dB within a certain maximum distance from the pond. For example, the rule could say no boat can be more than 90 dB when measured by a meter that is no closer than 50 feet from the pond. Or it could say no more than 85 dB by a meter no closer than 100 feet. The point right now is thinking about a new way of measuring, not the exact numbers. This would get away from such a fussy measurement standard and allow us to focus on the real goal, reducing the overall noise coming from our pond to help us get along with the neighbors.

 

[SayMikey]

I still think the on the beach bench test is the way to go. If we can come up with a number that equates to 92dB @ 50 feet on the water then all this gets real easy. Hmmm, weren't you the first one to mention that approach here.........

Let's take a step back and think about the objective of the noise limits for a second. Unless I'm confused, we're trying to quiet the boats down so people near the pond don't complain about the noise, right? If this is truely the case, then perhaps we should focus less on a rule that provides such a precise method of measurement.

As a straw man, maybe we should just have a rule that says your boat must be below some number of dB within a certain maximum distance from the pond. For example, the rule could say no boat can be more than 90 dB when measured by a meter that is no closer than 50 feet from the pond. Or it could say no more than 85 dB by a meter no closer than 100 feet. The point right now is thinking about a new way of measuring, not the exact numbers. This would get away from such a fussy measurement standard and allow us to focus on the real goal, reducing the overall noise coming from our pond to help us get along with the neighbors.

I think part of the problem is some boater objective is 92db when they should be striving for more like 88-90 to be sure to be legal. We have seen pipes that are quiet and pipes that wont work,its time to look for answers to the problem not disect the noise issue as its not going away

 

[Joe_Knesek]

They must be drilling out the stingers when they go to Bristol.

That's funny Joe. :lol:

And BTW, I never ever claimed to be an expert, don't put words in my mouth. :angry:

All I'm going on is many hours of what the dB meter tells me in straight up hands on testing.

I still think the on the beach bench test is the way to go. If we can come up with a number that equates to 92dB @ 50 feet on the water then all this gets real easy. Hmmm, weren't you the first one to mention that approach here.........

I agree with you on the bench test. I'm going to put my thoughts on paper this weekend and I'll share it with everyone to shoot holes in it but it will be a starting point.

 

[AWaddle322]

Don,

There is no such thing as cancelling effect of noise. What was seen at the nats with john browns single and his twin is realitevly easy to explain. His twin motors are not working as hard and or not reaching the rpm that his single is. Noise does not cancel out. Here is you a really easy test to test this. Put your favorite cd in your cd player(2 speaker system) using the mono setting. record your dbs and then simply unhook 1 speaker. There will be a three db drop. This is a known fact, not a theory.

Mikey,

Dont ever say one pipe will not work. There are ways to quiten anything down. Until such a time that it is proven that evansville db meters were given the correct db reading all of this becomes null and void. The real bad part part about all of this The IMPBA membership was given information concerning noise with information given using John equi's meter through the roostertail. what should really happen is the noise thing be put on hold or back to the way it was until the IMPBA memebership can get accurate information. What this really means is up until a time that we have a trust worthy instrutment for measuring noise we are all left in the dark. Evansville meter could be reading 94 dbs and for all we really know that 94 could actually be 104. O and one more thing sonce the noise rule is about quiting down the noise on the pond then why did we remove the part about all boats must have mufflers, when this was done all that happened is we allowed smaller boats to get louder, kinda seems against the goal to me .what about you?

Impba Board,

We the people of this orginzation need information quickly, we need to know if Evnasville meter was reading correctly or 10 db high or 10 db low, we have the second half of the racing to go this year and we need to know were there meters stand so that those that were to loud can get in compliance or dtermine that we are already in complaince. We need to be testing know and up intil the time we recieve this information testing is useless.

Sincerely,

Allen waddle

 

[Piston1]

Don, No!, you are still confused. Allen is right, read below, two sources of the same sound (twin engines) double the volume. Noise cancellation is a fact, it works in cars, airplanes, houses, etc., etc. etc., but it will never work on a twin because the sound emission from the engines are right on top of each other. You can experience some sound reductiion due to better thermodynamic/mechanical performance when you synchronize motors, but not due to active wave canceling.

Adding waves

If you add two waves together that are going in the same direction, and if those waves are in phase--that is, the peaks and valleys of the waves line up--then the amplitude or height of the waves will double. That would be like two sources of the same sound would double the volume.

Canceling waves

Now, if you add two waves together that are going in the same direction, and if those waves are completely out of phase--that is, the peaks of one line up with the valleys of the other--then the amplitude or height of the waves cancel each other out.

 

[SayMikey]

Don, No!, you are still confused. Allen is right, read below, two sources of the same sound (twin engines) double the volume. Noise cancellation is a fact, it works in cars, airplanes, houses, etc., etc. etc., but it will never work on a twin because the sound emission from the engines are right on top of each other. You can experience some sound reductiion due to better thermodynamic/mechanical performance when you synchronize motors, but not due to active wave canceling.

Adding waves

If you add two waves together that are going in the same direction, and if those waves are in phase--that is, the peaks and valleys of the waves line up--then the amplitude or height of the waves will double. That would be like two sources of the same sound would double the volume.

Canceling waves

Now, if you add two waves together that are going in the same direction, and if those waves are completely out of phase--that is, the peaks of one line up with the valleys of the other--then the amplitude or height of the waves cancel each other out.

ALLEN I AGREE THE MUFFLERS SHOULD HAVE STAYED ON THE RULE. WE HAD 2 METERS ONE WAS BRAND NEW THE OTHER WAS A YEAR OLD AND HAD VISITED SEVERAL RACES,AT THOSE RACES IT FOUND BOATS OVER THE DB. WHEN THE CD WAS ASKED ABOUT IT THEY SAID THE NOISE WAS OK,NOW WE NEVER SAW ANOTHER METER. ALSO I POINT OUT AFTER TALKING TO THE GUY RUNNING THE METERS,BOTH METERS NEVER VARIED MORE THAN 1-2 DB. AND WHEN JOHN EQUI HELD HIS METER BY OURS HE HELD IT IN HIS HAND TO HAVE BEEN A VALID TEST HE SHOULD HAVE PUT IT ON THE TRIPOD AND STOOD BEHIND THE METER. SOMEONE TELL ME WHERE TO SEND OUR NEW METER TO HAVE IT CHECKED AND I WILL AND PRINT THE REPORT THAT COMES BACK WIITH IT.......MIKE

 

[Preston_Hall]

Put your favorite cd in your cd player(2 speaker system) using the mono setting. record your dbs and then simply unhook 1 speaker. There will be a three db drop. This is a known fact, not a theory.

Correct. I remember this from the car stereo days. 3db = 2X supplied power

I'll go with twins not working as hard to account for less noise as well. You do not have to consider wave lengths at all because twins will NEVER be in "tune". Anybody that thinks two motors will stroke at even rpm for any length of time can have my 400mph Crackerbox for free.

There is plenty of good noise reduction information here to try. The said thing is that the only thing most will try is some kind of pipe or muffler.

I find it funny how some of the same people who said that this was the way to go with measuring db's are now doing a back stroke and saying that "we" need to do something. The "I" seems to have disappeared.

 

[Don Ferrette]

There is plenty of good noise reduction information here to try. The said thing is that the only thing most will try is some kind of pipe or muffler.

Unfortunately I think you might be right. h34r:

 

[Chris Wood]

Well since the fire got started again on this i will say one small thing.

I watched one heat of sport forty at the nat's that NOBODY, and i mean NOBODY was watching the meter.. i stood there the WHOLE TIME.. not a sole..

So how do you patrol something or how do inforce a rule that in SOME instances are not being inforced..

This rule is got so many confused as well as TO MUCH controversy for a already herting sport..

As preston said ( I ) would like to see something done with it, instead of letting it just continue to sit and brew.. If we don't make this PRIORITY ONE we will lose people, and fast...

My final 2 cents on this

Chris

 

[GMCSW7]

Noise cancellation is a fact but only by electronic!

Db is a measurement of amplitude! not frequency! correct?

steve

 

[SayMikey]

Noise cancellation is a fact but only by electronic!

Db is a measurement of amplitude! not frequency! correct?

steve

I watched one heat of sport forty at the nat's that NOBODY, and i mean NOBODY was watching the meter.. i stood there the WHOLE TIME.. not a sole UNFORTUNELY THE GUY MANNING THE METER SON RUNS SPORT40 GUESS YOU MISSED HIM WHEN HE WENT TO THE HEAD ALSO.....WE DONT HAVE COVERAGE TO PUT 2 PEOPLE IN EVERY JOB BUT DID THE BEST WE COULD AND STAND BY IT