Interested in how loud your bike is?

[jrandom]

A weighted, according to the regs

You'd bloody hope so aye.

'A' weighting is just a flat measurement of sound pressure energy, whereas 'C' weighting is an out-of-date oversimplified psychoacoustic model which weights some frequencies over others in the result.

[vifferman]

That's why the test is bogus.

It's also bogus because although some allowances are made for engine noise being higher on bikes, it is essentially and ostensibly/supposedly a test of only how much noise comes out of the zorst. I have a feeling that even though my muffler will pass the test, my bike may fail, as the cake mixaahh!! makes so much noise itself. Lucky I don't have a dry clutch (although I do have some clutch noises, sundry engine parts rattles, oil pump rattle, etc.)

If/when my bike gets tested, I may have to either try to muffle the engine or pack the zorst with sound-deadening materials (like hamsters, 10-day old porridge, or politicians....)

[saul]

That's interesting.

Does anyone know whether the exhaust noise test uses 'C' weighted dB SPL?

Yeh I should have had a look at his settings.

I would think that he would have just been on "A" - slow cause it was a static test and SPL but I didn't look.

Talked about the system being moderated heavily at the moment because "they" wanted to see results. Lol wonder what that means

[jrandom]

I would think that he would have just been on "A"

A lot of audio test gear, particularly stuff that's not cutting-edge new shit and was originally designed for PA type purposes, defaults to 'C' mode and needs some twiddling by the operator to get it reporting results in 'A' mode.

If it's being driven by a numbnuts spanner jockey I wouldn't be surprised if it's being left in 'C' mode by mistake, which would explain your high reading.

[Gremlin]

Yeh I should have had a look at his settings.

Yep, for extra info, it has to be A weighted, meter set to fast response (there are several modes), three measurements must be taken to one decimal point, which are then averaged and conventionally rounded to a whole number.

Spikes during testing mean the test must be excluded, and another taken, and then you have the site considerations to also take into account along with positioning of equipment.

I wonder if I could beat your score with my baffle still in... I just need the equipment

[pritch]

I know how loud my pipe is - the Staintune website lists the values somewhere

So too with Arrows.

When I discussed this "subjective" noise testing aspect with the WoF tester I use he told me that it's largely an attitude thing. Yours and his.

I took his comments to mean that if neither the noise nor the rider is obnoxious - no problem. Variation from that on either count? Problem!!!

Makes sense, they are human too. (Well most are :-)

[vifferman]

So too with Arrows.

Mmmmmm.... Arrows.

Makes sense, they are human too. (Well most are :-)

Welllll.... I'd say a fair proportion (at least many of those that work for VTNZ or VINZ or whatever it is) seem to fall into the "subhuman" (i.e., Petty Bureaucrat with a Grudge and Permanent PMS) category.

[Toaster]

Keep in mind fooling the WOF tester is only a partial solution. Once the exhaust is back to its normal loud self you may have it green stickered by the police for being too loud - then your so called WOF is as good as pigs weez in a yard glass.

[AlBundy]

Just a question...

Isn't dB exponential. Isn't 2dB at lower levels totally different to 2dB at higher levels...

So, it's all well saying it's 2dB out but it's make a huge difference when borderline high...

[mashman]

One thing that hasn't been discussed, not that i've read anyway, is that a bike will make more noise (pitch or sound???) the higher in the rev range it goes. If they are going testing for WOF pass, does each bike have to be under a certain DB level at a certain point in the rev range and under certain test conditions. I have open Akras, not the loudest, but they're pretty noisy. When the guy across the road from me starts his Harley it pales mine into insignificance. How can they justify how noisy your bike is?

[Gremlin]

If they are going testing for WOF pass, does each bike have to be under a certain DB level at a certain point in the rev range and under certain test conditions.

Depends on the bike. There are set rev limits for certain machines, and it varies according to 2-stroke or 4-stroke, how many cylinders, valves per cylinder etc.

Ie, my zx10 is a 4 stroke, 4 cylinder, which means it will be tested at 4500rpm.