Originally Posted by pencil shavings (Post 1927673)

my bike with a straight through two brothers racing can is super quite below 5k rpm, then comes to life, and really makes a noise after 9k rpm :)

Originally Posted by ThEGr33k (Post 1927769)

Remember that for every 3dB increase the noise gets twice as loud. ;)




So surly it dont make noise too often? :rolleyes:

Originally Posted by Mr Speirs (Post 1927958)

For a percieved doubling in volume a 6-10db increase would be required.

Originally Posted by ophic (Post 1927967)

Personally I would never be able to say that something is "twice" as loud as something else, as its so subjective. Even the same sound at different volume levels - if someone said "turn it up so its twice as loud" i'd have only a very vague idea. Its just not quantifiable to me. And I'm a trained sound engineer :(

Originally Posted by Mr Speirs (Post 1928188)

I understand what you are saying I couldn't tell you when something was twice as loud as something. However the comparison is more to illistrate that a doubling of actual power would read on an unweighted meter as a 3db increase. However if the Meter was A-weighted like most decibel meters must be, as this is the way human actually hear things, it wouldn't register as much of an increase and in effect the power would have to double again to reach the same reading as the unweighted meter which was reading half the power.

Originally Posted by svtomo (Post 1927475)

hi,
just been looking at doing my 1st trackday and noticed that there is a 105 db noise limit, just wondered if anyone could try and spell out how load that is in the real world.
i have a 350mm delkevic exhaust on my bike and its fairly load, used to have a fuel exhaust on it, iv noticed there is a few people on here with them on and wondered if they have eve been tested as i think that was louder than it is now.
any help/advice muchly apprieciated,
cheers

Originally Posted by Miss Alpinestarhero (Post 1929403)

To put it in perspective..check these two links out: linky1 & linky2

But decibels (sp?) are not linear like a ruler, its logartithmic. For example if one bike has a sound level og 60db then 4 bikes would be a hell of a lot louder (i.e. 60db x 4).

so is the 105db limit per bike or overall? ;)
No idea how you'd work out how loud your bike is though.

Originally Posted by Miss Alpinestarhero (Post 1929403)

But decibels (sp?) are not linear like a ruler, its logartithmic. For example if one bike has a sound level og 60db then 4 bikes would be a hell of a lot louder (i.e. 60db x 4).

Originally Posted by ophic (Post 1929444)

thats not quite right. 4 bikes would not make 240dB.

1 bike, say 60dB
add a second bike which makes an identical noise - you've now got 2 bikes at 60dB each, so you've doubled the sound intensity - thats now 63dB, as 3dB represents "twice as loud". (I always thought it was 6dB but that could be something else - its been a few years since i was at college).
Add another 2 identically sounding bikes, you've doubled it again - so 66dB.

Now these bikes would not normally be making identical noises in sync with one another. Sound is a wave - 2 identical waves in phase would produce double the sound intensity, but entirely out-of-phase would produce silence. So in fact with 4 bikes all producing 60dB - you're probably not gonna get to much more than 61dB there.

Originally Posted by Miss Alpinestarhero (Post 1929462)

Ah i see. Ta for the correction :D Now Ive re-read what I said, 4 bikes making treble the noise sounds really wrong :lol: If that was true, then I guess everyones ears would have popped at the AR given the amount of bikes there :shock: