Idle seems a bit high... but 13K sounds about right. No pun intended! :lol

 

probably not far off. a friend of mine has an industrial decibel reader, properly calibrated etc. he measured mine a while back and it was over 100db at idle

 

you will find decibel levels are a bit deceiving depending on where your noise floor is.. 115db sounds pretty bloody high to me so I would consider
revising where you place the recording device and what your surroundings bring to the picture.. if your noise level is such that the unit is already reading
a high level without the bike coming into the picture then its likely the bike's supposed level is actually a little lower. Frequencies can compound
on top of each-other and create an unrealistic picture.

in terms of the readings at 13k rpm are concerned though noise floor really should not effect much since the bike's exhaust will over-power most of it..

locally they've had a noise regulation for a few years and there is still no real consensus where the mic should be placed to get a 'proper' reading.
just to be clear, grabbing random readings while the biker is sitting on the side of the freeway will not yield accurate results and it can be fought in court
as they're starting with a very high noise floor as is. :yesnod

most coppers are not trained properly using these devices either, I'm a sound engineer and there are plenty of irregularities to be expected,
even on-axis vs off-axis will yield different results depending on accuracy of equipment. You mention software, I would start with the hardware
side of things, ideally i would use a directional cardiod microphone, off-axis to tips of exhaust or the sound itself will overpower your mic and again
your readings will not be accurate. Definitely do not use a condenser mic as they are entirely too sensitive for such readings. I'm not certain on what
distance you should be testing at but look around online and see what the manufacturers of said devices suggest and go from there. Decibel readings
can be hard to pin down even in controlled environment, never-mind out in the wild.

lastly, there is a thread on here which a member so kindly posted showing very accurate reading levels on various exhaust and they did a pretty impressive job :fact



incorrect assumption, and actually your reading sounds much closer to reality.. i believe they should be reading around 105db max at idle..

you need to understand how decibels really work.. there is a MASSIVE difference between 100db and 115db... lets put it this way, and yes you can verify
this information anywhere online.. 3db in fact doubles the amount of perceived sound, so going from 100 to 105 you've already doubled (+) the amount of
perceived noise, cranking it up to 115db as you can imagine will yield an ABSURD amount of difference in actual sound.. they're not even in the same ballpark. :no

115 at idle seems really high. That's loud. A THX calibrated movie theater only goes up to 105 DB through the main frequency range.

115 DB is rock concert level.

-Chris

CORRECT!! 115db is an unreal amount of noise coming at you.. if most aftermarket pipes were to idle at that level they'd actually be saving lives.. :lol

Idle seems a bit high... but 13K sounds about right. No pun intended! :lol

yep, i agree with this assessment.. when trying to capture decibel levels, trying to get an accurate reading on an acoustic guitar in a crowded space
will be a little difficult and your readings will not be very accurate, thats kind of like recording idle levels. Mind you bring in an amplified guitar with
James Hetfield jamming away into the same room and its pretty obvious just about anybody will be able to give you a good db reading. Thats a little
closer to what a bike exhaust should cause at 13k rpm, there's not much out there that will overpower it so its likely an accurate reading

 

115 at idle seems really high. That's loud. A THX calibrated movie theater only goes up to 105 DB through the main frequency range.

115 DB is rock concert level.

-Chris

 

All this sucks. Jennings GP which is my closest track has maximum of 104 db. They test the DB of each bike as it goes down the straight away at WOT from 50 feet away.

 

I see, if you're taking reading dead center right in front of the exhaust then that would be cause for such high readings. I seriously doubt state regulations require
readings direct at the exit as they will never be accurate with just about any microphone you try. The reason for this is most mics are designed to have some sort
of air flow possible between it and its source even when accent mic'ing. Accent mic'ing in my books is about 4-6 inches away :fact

again, for clarification most people dont fully understand decibel readings. 3-5 db difference looks like nothing on the number scale, but really 5db increase
you need double the sound and then double it again!! (vice-versa when its a 5db decrease) its a pretty noticeable difference, but of course if you're just getting
db readings on software you would never notice this. Ideally you need to listen to the recorded material and it should be pretty clear, so yes I would go with the
lower reading every day of the week and twice on Sunday.

But of course as I mentioned I would not be taking readings with the mic faced straight at the exhaust exit. Most cardiod microphones while being directional do not provide
very good recordings when set dead on straight at the source. I would recommend a 45 degree angle to exhaust from the side for more accurate readings. If I were recording
the actual sound I bet you would have high db readings and i would still not be able to use most of the recording, sadly this is how microphones work in most cases. Most guitar
amp recordings you've heard are actually a combination of on-axis and off-axis recordings but almost always you end up with the off-axis recording being the cleanest. Peak
volumes are never anything to brag about, you need your headroom for other frequencies. I would think 6 inches from the exhaust exit would be okay, 6 feet is probably too far
as you're recording the environment more than anything.

I think your environment is also causing high readings to begin with, in canada we consider such a road a highway, not quiet a freeway but definitely not ideal recording environment :no



local race track has similar noise restrictions. they all run oem exhaust with de-cats at most. I dont even know if anybody gets away with aftermarket can with silencers..

105db is easy to reach with most aftermarket at idle.

 

Thanks for the great info bacchus! I told my PM that he should probably pull the reader further away to get a "more" accurate reading but he insisted that the state we're working with wants the levels read right at the exhaust exit. Initially he read from probably two inches away from the exit, dead center of the flow. He did pull it back about 5 or 6 feet for a couple of tests and the db level shown on the meter didn't decrease a whole lot. It may have gone down 3-5 dB but I don't remember. In the end, the results I posted up top were taken with the reader about 6 inches from the exhaust exit dead center.

To add some background, we took the readings outside about 100 yards from a semi-busy 45mph road on a day with the slightest breeze. We didn't take a dB reading with the bike off, though we probably should have.

 

The company I work for is solely contracted by State governments, and I think you might be surprised at the lack of knowledge that law and policymakers have here in the U.S. I know, everybody says that politicians are dumb when they're unhappy with them, but seriously...they "can be" (trying to be tactful here 0 ) All this to say, those who are in charge of communicating regulations to us, the software company, did inform us that readings are to be taken at what you and I would consider to be too close to the exhaust exit. Anymore, I just shake my head and do what I'm told when it comes to stuff like that :drink:

They'll be taking these readings at dealerships and repair shops; places that I'm sure will not allow accurate readings in the first place, so I'm not sure why this is being implemented really. Oh well, I live in a different state, and Indiana is pretty chill when it comes to stuff like this :wink2:

 

Anything other than vehicle emissions testing being implemented via the feds is a money making scheme more than anything else. Like exhaust gases stay between state lines right.

 

Actually 3db is considered the minimum increase in SPL we can even perceive. So it's not very noticeable at all. It's true that a 3db increase is double the sound output but that isn't how we hear it.

It takes about 10 db increase in SPL for us to actually perceive it as twice as loud.

And your noise floor will only combine with what you're measuring if the frequencies and phase overlap fairly closely. Taking exhaust SPL measurements indoors is probably the least accurate way it could be done, unless you are a good 50 feet from any wall. A bike exhaust will most likely have low enough frequencies to bounce off the wall and combine to make the reading higher than reality. Like how your subwoofer is louder when you stick it in the corner.

Might not matter if you have the measurement mic stuck in the tailpipe though. But a too close measurement taken indoors might be the best thing for motorcycle owners in the state. It should take about 5 minutes for an attorney to have that crap thrown out as not valid.

-Chris

 

It takes about 10 db increase in SPL for us to actually perceive it as twice as loud.

you're getting into a tricky area, audio perception is something that is not commonly or energetically perceived the same across the board.
best i can put it is its much easier to tell between a 'clinically blind' person and one that is considered to 'see' than it is to tell between
the several gray areas between those who have a 'trained ear' and those whom the rest of us would consider 'bloody deaf'. If you cant
perceive 3db differences i would consider you to be part of the latter :yesnod


I constantly work with 3db plus or minus in the studio. its very noticeable, in fact when we mix down most compression is in 3db steps. If i were to compress
a guitar or vocal by 10db it would be utterly lifeless and the artist would probably kick me in the junk if i tried to mix them into a song this way, same goes with
mastering, work in 10db increments and you're a shitty club dj at best. Really basic explanation is I will generally use tube compressors with soft knee set at max -3db compression
which will effectively allow me to raise the volume of your mixed track into the rest of the song. The final result by gaining that 3db of 'sound pressure' back is that your
guitar or vocal will be 'twice as loud' in the mix, provided of course i've tuned the instrument's perceived frequencies to jive with the rest of the track. Which is why us
sound engineers just cut through the bs and call it 'twice as loud'. Now dont ask me to explain 'compression' as that is a whole other thread :hammer:

i will agree though there are different terminology at use here and a 3 dB increase is basically doubling in power,
which is not entirely accepted as volume but i figured it would be easier to get the discussion started.

but Technically you would be correct going by the following generalist chart. most 'average' listeners may not be able to tell the difference.

random copy/paste off Sweetwater forum, sounds pretty accurate

3 dB = twice the power (Power respectively intensity - mostly calculated)
6 dB = twice the amplitude (Voltage respectively sound pressure - mostly measured) *note, i believe this is peak to peak since its audio sine-waves
10 dB = twice the perceived volume (Loudness nearly sensed psychoacoustics)

now, going with the above, tell me if you can perceive the difference between a movie theater sound system and say a Radiohead concert from the 1st row..
difference is 'only' about 10db but you will find very few people that catagorize that as merely TWICE AS LOUD.. this is why things get tricky

i'm a big fan of both film and live audio, there is a massive difference between the two, mostly because at these levels you're dangerously close to the
human ear's threshold of pain, so while your approach will be relatively accurate at mid of the road SPL readings, its not always a guaranteed constant.

The company I work for is solely contracted by State governments, and I think you might be surprised at the lack of knowledge that law and policymakers

yep, i understand this.. Its the same out here in BC. its clearly just a money grab aimed at those suspected to have plenty of it to go around.

i will say this though, a quick little search shows the new Arrows full exhaust system for the 2015 R1 is rated at 115db :dunno

This guy knows something Thanks for sharing that info.

i'm just an audio geek.. I received my diploma as a Digital & Analog Rec. Sound Engineer back in 2002.

 

I've been learning from a bunch of talented and well educated speaker designers for about the last year. Quite a few have studio backgrounds as well. None of them call 3 db twice as loud. They call it the minimum change in amplitude the average person will perceive.

I think I can notice about 2 db but I can't promise I could do it in a controlled test. I'm sure I don't need to tell you that it's frequency dependent as well since our ears are much more sensitive to some frequency ranges. Google Fletcher Munson curves if needed.

I don't think there's anything tricky to it but I'm not going to get into an argument about it on a motorcycle forum.

-Chris

 

no worries, yes i understand its all very frequency dependent as i've noticed everyone has a certain range which stands out more to them than others.

maybe its just use of different terminology which is confusing. its no big deal really I work on 3db increments when mixing, I was just trying to explain
that if you go with a 10db adjustment using the analogy that is what your average joe considers doubling of halving in sound then most mixes we listen
to today would sound utterly lifeless with very little expression. Its a very large adjustment. You should definitely notice 2db Within a mix, a track which has
been compressed to regain 3db most would generally perceive it to be twice as 'loud', or if you want to be specific, it would CUT THROUGH twice as much, but
then we're talking within a certain mix, which again can be as-cued due to frequency perception. There are many ways to describe what you're experiencing.

You are correct Ideal terminology to use is that it is twice as powerful as we're talking Sound Pressure Levels.
If it makes it easier just substitute one word over the other wherever you see it used above :lol

the tricky part of it i mention has everything to do with threshold of pain we all experience at a certain SPL, meaning its gonna be a little different based on your own previous exposure.

never-mind the fact that if you're gonna carry out analogies used above directly to discerning between different exhaust you will get a different answer
every time as very few of us stick our ears right up to the can to hear differences above 105db, and you would only really appreciate 125-130db if you're
in a dyno-room, or not really as you're likely to be covering your ears well before you reach those levels.