Sparky_Spit Posted July 9, 2021 Report Share Posted July 9, 2021 My car has been noise tested by CMC rally scrutineering at 96db at 1 metre, and at Goodwood at "less than 98db", at 1 metre. I understand that. But I'm a bit confused with db levels in practical use. I know that in audio electronics an increase of 3db is a 100% increase in level, a doubling of amplitude, but this does not mean that it is twice as loud in audio terms. Why is that? If a 3db increase gives you 100% more amplitude why is it not audibly twice as loud? Link to comment Share on other sites More sharing options...
dougbgt6 Posted July 9, 2021 Report Share Posted July 9, 2021 I think ears aren't linear? And there's frequency to consider 0 to 20k in children, 0 to 15k, in an adult or 12k in my case. I blame the Quo. Doug Link to comment Share on other sites More sharing options...
Chris A Posted July 9, 2021 Report Share Posted July 9, 2021 7 minutes ago, dougbgt6 said: I blame the Quo. Saw them perform last century. It was after their hit Pictures of Matchstick men. I used to go to a pub on the Fulham Road in London at the weekends, free group but expensive and terrible beer! The regulars were all rock/ heavy metal fans, so there was a collective groan when they were announced. After their first number the response was much better! A 'bad' group weren't booed, there was just a couple of seconds silence at the end of a number then the chattering started up . . Link to comment Share on other sites More sharing options...
Sparky_Spit Posted July 9, 2021 Report Share Posted July 9, 2021 Ah yes, you are correct Doug. Human hearing is not linear, but something like a logarithmic curve, so it would be a much higher multiplication factor that would sound twice as loud, and therefore a larger increase than +3db. Link to comment Share on other sites More sharing options...
dougbgt6 Posted July 9, 2021 Report Share Posted July 9, 2021 2 hours ago, Chris A said: I used to go to a pub on the Fulham Road in London at the weekends, The Greyhound? I used to go there! Dreadful Bands, unpleasant beer, but pretty girls. We kept going back, for some reason. Doug Link to comment Share on other sites More sharing options...
Chris A Posted July 9, 2021 Report Share Posted July 9, 2021 1 hour ago, dougbgt6 said: The Greyhound? I used to go there! Dreadful Bands, unpleasant beer, but pretty girls. We kept going back, for some reason. Doug I can't deny it. 😒 Link to comment Share on other sites More sharing options...
Anglefire Posted July 9, 2021 Report Share Posted July 9, 2021 On 05/07/2021 at 15:35, JohnD said: I have a "real" sound meter, and inside my race Vitesse, which is stripped of all potentially sound deadening trim, I get 98dB. It's so loud in there that I wear ear defenders while driving it on the road, without a helmet. Otherwise .... sorry, what did you say? That level of noise is equivalent to standing next to a chain saw, and it WILL damage your hearing after just a few hours exposure! That's why tree surgeons wear defenders! The legal limit at the roadside is 74dB. The limit on the race track is 93db at 2 metres 100dB inside a road-going, fully trimmed car? I don't think so. Or I hope not, for their ears sake! John Surely the limit depends on the track? I'm sure at Mira the limit was 98db (antilag not allowed) - other venues are 100db - and Le Mans was higher than that - so the BMW M whatever rear engined car could run with basically 2 3" or 4" pipes off the manifold through the turbos and out the back - they had another exhaust for noise limited tracks that apparently twisted around the engine bay to get the silencers in and also robbed them of a measurable amount of power. Link to comment Share on other sites More sharing options...
JohnD Posted July 9, 2021 Report Share Posted July 9, 2021 I'm quoting MotorsportUK competiton regulations, Anglefire, which apply to any circuit, stage or other venue in the UK that operates to their regs. See the Blue Book (The Yearbook) Section J, page 153, Chart 5.18: https://www.motorsportuk.org/wp-content/uploads/2019/12/145-154-Vehicles-J.pdf I don't know anything about noise regulation in France, but MIRA doesn't run to Motorsport regs. JOhn Link to comment Share on other sites More sharing options...
Chris A Posted July 10, 2021 Report Share Posted July 10, 2021 9 hours ago, JohnD said: I'm quoting MotorsportUK competiton regulations, Anglefire, which apply to any circuit, stage or other venue in the UK that operates to their regs. See the Blue Book (The Yearbook) Section J, page 153, Chart 5.18: https://www.motorsportuk.org/wp-content/uploads/2019/12/145-154-Vehicles-J.pdf I don't know anything about noise regulation in France, JOhn Probably 3 levels of acceptability: 1. Quick shrug of shoulders : All ok 2. Long shrug of shoulders : OK, but at the limit 3. Long shrug of shoulders & forearms extended with palms of hands facing up: Putain! Link to comment Share on other sites More sharing options...
JohnD Posted July 10, 2021 Report Share Posted July 10, 2021 1&2 bone chance Mon Ami! 3 M.Langlais, Non! Link to comment Share on other sites More sharing options...
Chris A Posted July 10, 2021 Report Share Posted July 10, 2021 24 minutes ago, JohnD said: 1&2 bone chance Mon Ami! 3 M.Langlais, Non! C'est ça 🏎️ Link to comment Share on other sites More sharing options...
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