Should there be a DB limit

[02Tac]

  Seeing as any discussion about "loud pipes" denigrates into total BS, I thought I would ask if people thought there should be a sound limit.

 Bear in mind that the SAE test allows 92 db at idle and up to 100 db at a higher RPM which is actually quite loud.

[Sport-Touring]

[Bounce]

There's already a federal standard.

Noise standards that apply to OEM motorcycles are based on a test procedure developed by the Society of Automotive Engineers (SAE) that measures vehicle noise levels during acceleration at a distance of 50 feet. Although this is the most representative test procedure available, detailed requirements for the test course make this test impractical without a test track. In recognition of the practical problems of running the drive-by test, SAE has developed a much simpler procedure suitable for use at the roadside or in a parking lot. This test, SAE J1287, involves measuring the exhaust volume of a stationary motorcycle running at 50% of its maximum allowable engine speed while in neutral. To limit the influence of other noise sources in the vicinity, the procedure specifies measuring the noise level at a distance of only 20 inches to the rear of the exhaust outlet. Because of the short distance between the exhaust outlet and the sound level meter, the absolute noise levels measured with the J1287 procedure are higher than on the drive-by test; however, the ranking of vehicles is similar.

http://standards.sae.org/wip/j1287/

The SAE J2825 standard, prepared by the SAE Motorcycle Technical Steering Committee, recommends a decibel limit of 92 dBA at idle for all machines or -- using the Set RPM or Swept RPM Test -- 100 dBA for three- or four-cylinder machines, and 96 dBA for bikes with fewer than three or more than four cylinders.

set=50% of redline

[garry]

Obnoxiously loud ANYTHING should controlled. Super loud car stereos with thumping subs, trucks w/ jake brakes, whatever. Don't just pick on motorcycle exhaust. More of a general noise pollution ordinance. I guess the difference is that some things are user-controllable and can be turned down (stereos), but straight pipes on a cruiser are always "on".

Note my emphasis on obnoxiously loud, not normal after-market loud.

[SLK50]

Maybe I'm getting old, but any exhaust that
causes me to turn my head ( IOW, gets my
attention ) is too loud.

Since perceived volume doubles every three
decibels, 100 db would be 267% louder than 92.

[02Tac]

Note my emphasis on obnoxiously loud, not normal after-market loud.

Therein lies the issue, without a set db limit the discussion devolves into what each person thinks is OK or obnoxious. Hence the poll question.

[02Tac]

Maybe I'm getting old, but any exhaust that
causes me to turn my head ( IOW, gets my
attention ) is too loud.

Since perceived volume doubles every three
decibels, 100 db would be 267% louder than 92.

This video actually puts in perspective, and it is only the idle test.

https://www.youtube.com/watch?v=inCBgnvOXgI

[Bounce]

Maybe I'm getting old, but any exhaust that causes me to turn my head ( IOW, gets my attention ) is too loud.

Hater of wondrous V12 supercars, eh?

I don't know when it stopped but I specifically remember general noise ordinances and their enforcement when growing up.

[SLK50]

Hater of wondrous V12 supercars, eh?

I should have qualified my statement as being relative to motorcycles.

And as far as getting my attention, I meant as a distraction.
For example, when an exhaust's volume causes me to interrupt
a conversation, it's too loud.

[02Tac]

I should have qualified my statement as being relative to motorcycles.

And as far as getting my attention, I meant as a distraction.
For example, when an exhaust's volume causes me to interrupt
a conversation, it's too loud.

All well and good, but not a good standardized way to judge things.

[JamminJohn]

Maybe I'm getting old, but any exhaust that
causes me to turn my head ( IOW, gets my
attention ) is too loud.

Since perceived volume doubles every three
decibels, 100 db would be 267% louder than 92.

That's not true.        3db is the lowest easily perceived volume change.
                   TEN DB is TWICE AS LOUD !
The 100db exhaust is NOT twice as loud as the 92db exhaust !

3dB = twice the power
6dB = twice the amplitude
10dB = twice the perceived volume

Adding up two 12dB noise sources will get you, on average, 15dB (which will not sound twice as loud)
I was working with a sound engineer and asked for a level to be dropped 3db.
Their reply was “so you want it half as loud?” and I said “No, 3db” which was countered with “3db is half the volume”.
So that’s what prompted me to look into decibel changes and how that translates to our real world perception.
It is true that to increase a volume level by three db requires twice the power, which I think is where the confusion is.
A doubling in power does not equal a doubling in audio perception.

It was determined many years ago in controlled audibility testing, that the following rules were generally accurate among the population:
6dB SPL increase is perceived as an approx. 50% increase in volume by a sample group.
10dB SPL increase is perceived as an approx. 100% increase in volume by a sample group.

Another Explanation
A 3dB increase is twice as loud, in that increasing the level by +3dB by definition means twice as much audio energy is now being pumped into the room – well, actually 1.995 times as much, thanks to the wonders of logarithms.
But the human ear’s response is also logarithmic, so twice the energy does not sound like twice the volume.
There is, of course, no clear point where anybody’s going to say “ah, that’s now precisely double as loud as it was before”; there’s no little mental VU meter needle.
But the general rule of thumb is that people tend to call a 10X, or 10dB, increase in audio power “twice as loud”, if you insist that they indicate such a point, and this is backed up by neurological studies.

                                                               JJ

[02Tac]

Still boils down to the simple fact that we need a sound standard to use and the J2825 test seems to be the best compromise out there between the bullshit of open pipes and the thought of not allowing any modification from stock.

The thing is, that in order for any standard to work, we need to have enforcement authority, out side of the periodic registration inspect (for those states that have them). I say that because here in Delaware they stopped checking exhaust sound levels (motorcycles and cages) because there is no enforcement outside of the inspection lanes. The asshats that run loud pipes would simply slap on the stock pipes, run through inspection and put on teh stupidly loud pipes again when they got home.

[JamminJohn]

I think that there is no enforcement because cops own private bikes are Harleys with loud pipes on them.
They ride loud bikes so they are not going to bother loud bikes.
Most every off duty cop that I have seen rides a Harley.

                                    JJ

[olderigetfasteriam]

I think that there is no enforcement because cops own private bikes are Harleys with loud pipes on them.
They ride loud bikes so they are not going to bother loud bikes.
Most every off duty cop that I have seen rides a Harley.

                                    JJ

Quite a sweeping assumption this.

[02Tac]

Here, in Delaware, it was simply that the test method did not lend itself to a road side application. The J2825 test does and is why I am contacting my representatives to institute it.