loud exhausts save lives...

[daktulos]

Originally Posted by Bibio

i often wonder why they dont incorporate white noise into emergency vehicle sirens.

I think there have been in the past, but if I heard white noise I may not associate it with an emergency vehicle. I'm pretty sure I've heard a wailing siren with a crunch in the middle fairly recently.

[ophic]

Originally Posted by Bibio

the lower a note becomes the less directional it is. white noise is a fantastic directional noise that humans can hear where the source is. low frequency bass note on the other hand and you are less likely to hear the source, get below 30hz and you have no chance hearing where its source is.

i often wonder why they dont incorporate white noise into emergency vehicle sirens.

All true about bass frequencies. Not so much about white noise. As it's flat and uniform, it's difficult to tell the source from the reflections. This is why sirens tend to be mid-pitched and modulated, which also has the advantage of grabbing your attention.

As an aside, no vehicle exhaust emits only low frequencies and are therefore easily directionally located.

[Dave20046]

Originally Posted by ophic

Nice post and a good find. I'll be sure to keep that study handy.

"Of course I wasn't speeding Officer, my v-twin is just a bit noisy"

Seriously though it does give grounds to discredit any witness that says you were going too fast if your vehicle is noisy, thereby levelling the playing field once again.

I may not be a good example of the average Joe, having obtained a degree in Sound Engineering.

Exactly, it's scary people would be out there looking to point the finger like that but it happens I've heard of instances where people said a bike was going too fast but couldn't even recall the colour - for that reason I'm glad the studies were done!

Yeah, you're somewhat 'different'
Also , I think it's as much to do with the way the brain forms memories as it is to do with sound and speed perception. Any copper will tell you the varying accounts of incidents they get. Your brain connects certain dots based on assumptions then passes it onto your conscious as fact/memory, I know I've had distances way out when I've tried to recollect them before.

[SV650rules]

Been proud owner of SV650 AL7 since end of April this year (my first Suzuki) - absolutely great bike does everything I want, engine is a real gem. First thing I fitted was a couple of 10watt Cree LED spots on the handlebars (used a bracket off mirror mountings) - these are mega bright and I feel a LOT safer as people I have ridden with confirm they are visible from the European space station even on a sunny day. May get a different exhaust next year although stock exhaust noise is OK, but being as most bike accidents happen when people pull out on bikes, don't think a loud exhaust will help as much as a couple of proper bright LED daylight running lights (they are on a separate handlebar mounted switch and can also be on with headlight at night where they give a great spread of light). Car drivers can also see me better in their rear view mirrors as I have had many drivers pull over a bit when I have been filtering - since I have had spots fitted no-one has jumped out of a side road or pulled out when I have been overtaking them.

IMHO all that loud exhausts do is p!ss people off and get bikers a bad name.

[ophic]

Originally Posted by SV650rules

...but being as most bike accidents happen when people pull out on bikes...

True that. The police call it "right turn violation".
There are things you can do to mitigate the risks. Bright lights as far apart as you can get them on the bike is one of them (y). Even better if you can get them away from the main headlight as well to form a triangle. It makes your oncoming image "larger". More presence.

I agree that any exhaust loud enough to be of any real use in these situations at a typical 30mph speed would be fairly obnoxious.

[tom_e]

Originally Posted by SV650rules

IMHO all that loud exhausts do is p!ss people off and get bikers a bad name.

You'll probably find your bar mounted sun beams are probably ****ing off a lot of drivers as well, they're going to be just the right height to dazzle I'd imagine.

[ophic]

Originally Posted by tom_e

You'll probably find your bar mounted sun beams are probably ****ing off a lot of drivers as well, they're going to be just the right height to dazzle I'd imagine.

The beemers and trumpet adventure style bikes I've seen them on all mount them low down, giving that triangle I mentioned. Might also increase effectiveness in fog or something.

[Blapper]

Interesting that the IAM instructor that did my assessment had an Agrophobic on his R1200GS...

I rode with Viney at the weekend and his exhausts are - erm - 'unique'. It was great to follow him through traffic as my standard bike cannot be heard by car driving eejits with their muzak going but his SV shakes their cages a treat. The seas just parted in front of us.

I see what ophic says a couple of posts up, but on balance, there is no doubt in my mind that they do help some and any help is a good thing. Trouble is I live down a small drive with two other houses and it would wake them up when I get home late so I can't get any.

[SV650rules]

Originally Posted by tom_e

You'll probably find your bar mounted sun beams are probably ****ing off a lot of drivers as well, they're going to be just the right height to dazzle I'd imagine.

Yes they are at the same height as most SUV / 4x4 vehicle headlights, and they P!ss a lot of people off as well.

At least mine are pointed down and towards the kerb and shine on the boot of car in front, and at least I'm only p!ss!ng off one person at a time, not the whole neighbourhood and I can start my bike on my driveway early in a morning and my 'loud' lights don't wake the neigbours. I normally keep a fair distance back from vehicle in front anyway, and if I am going to be stopped behind a car for any length of time (at traffic lights and junctions) I turn the handlebars towards the kerb to get lights out of their mirror - I will be glad if they are 'noticeable' in a cars rear view mirrors as at least they will know I am there.

'motorbike' and 'noisy' are inextricably linked in the mind of the non-biker - and bike manufacturers go to a lot of trouble to make bikes reasonably quiet, my mate had an Aprillia V twin and fitted a 'track use only' pipe to it, when he was on morning shift he left his house at about 5 am (and on afternoon shift he arrived back home after 11 pm), non of his neighbours would speak to him (wonder why). If car drivers took it into their heads that loud exhausts would make them safer the world would be a very noisy place. My lights cost a fraction of the cost of a new exhaust, so I'm happy.

[madcockney]

Where I live we have a lot of cars with "go faster exhausts" fitted. There's an SVU that sounds like it's track car going around the track when it's only doing 5-10 MPH. Personally I have no sympathy for vehicle operators that use "Not For Road Use" exhausts and get done, and I can understand the locals annoyance with them. (I also have never had sympathy for those that have lost there licence for DUI, as well as having no sympathy for those being done for driving using a non hands-free phone whilst driving. I feel that unless more get detected and prosecuted for using phones then drivers will think that they can get away with it, but a lot of it is educating people and making them realise the effects of using a mobile whilst driving.)

Regarding the lights on the handlebars. I find dipped lights in my eyes because they are on the vehicle at a height to do that to be very annoying and in some instances outright dangerous. Back in the 60's and 70's, pre EU, cars were having spotlights fitted to them and many were roof mounted. Lights though not as effective as today's would blind you. Eventually the police, in London anyway, started to prosecute owners of vehicles and those driving them and over time the habit ceased. I don't recall what part of the law was used, or whether it was changed to handle this issue. I believe that you can still have them fitted but must not be operable whilst moving, must be able to be dipped, or must be completely covered. However many lorries have over cab high intensity lights that are on and switched off for approaching vehicles. This maybe one of those things that are allowed under vehicle type approval and maybe an area that the UK adjusted to conform to the EU. (The ex and current traffic cops on here should be able to clarify.) Having ultra bright lights mounted high enough to blind oncoming vehicles with no dip I would have thought comes under the same heading. Personally I find it disrespectful to other road users and is something that we don't want to do is antagonise them when we want them to accept us as bikers and be considerate towards us
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