Cars with no noise.

[Avocet]

Many emergency vehicles now incorporate white noise into their sirens so as we can work out which direction they are coming from - it really is amazing how well it works, our ears / hearing system is quite remarkable in its ability to work this complexity, but it does. I guess the original siren sound is to let you know its an emergency vehicle, and the white noise gives direction and speed.

And yes cyclists can here any vehicle 20mph and more very easily just from tyre noise, can even work out when the vehicles starts to slow down (which is great as that signifies they have probably seen you). The big problem with hearing on a bike is wind noise, and riding into a strong wind is not only unpleasant due to the effort required - it also removes your ability to hear vehicles approaching from behind which is quite unpleasnt, and no matter how often you look over your should someone will suddenly pass when you were not expecting it.

Yes, they went away from the old "bee-baw" sirens and over to the American style "whoop-and-wail" style sirens because the latter could be changed from "whoop" to "wail" at junctions and other points where people listening had just"zoned-out" and a sudden change usually wakes them up. The latest evolution has been to incorporate an element of white noise as well - and for exactly the reasons you state.

If it's very windy, or I'm going down a fast hill on the bike, then yes, the wind noise drowns out the noise of a following car - which is one of the reasons I said I wouldn't want cars to get any quieter.

 

[Harry Bloomfield]

Yes, they went away from the old "bee-baw" sirens and over to the American style "whoop-and-wail" style sirens because the latter could be changed from "whoop" to "wail" at junctions and other points where people listening had just"zoned-out" and a sudden change usually wakes them up. The latest evolution has been to incorporate an element of white noise as well - and for exactly the reasons you state.

Aside from the usual noises, around here they also have access to a very low frequency, very loud booming horn of some sort. Fire station is half a mile away, and their route to the local motorway takes them over a single track bridge over a railway, not far from me. If they are in a hurry, they sound that horn on approach to that bridge to clear their way. Drivers cannot see what might be coming, until they drive partially into the path of vehicles already on the bridge.

 

[Scoop-20]

That's the first i heard about these 'white noise' sirens.
Interesting.

 

[ericmark]

Traditionally the railway engines here would have had bells and whistles, the bell would be rung all the time it was travelling through the street,

since it no longer goes through the streets the bell has gone, when the flying scotchman went to USA it had to have a bell added as in USA many railways are unfenced.

We have seen in this country environmental friendly reversing bleepers which monitor the back ground noise and adjust their volume to match back ground noise.

However the idea of twin horns seems to be just to make them louder, not to adjust how much noise, and I know with cars sounding horns as they pass me on a bike, or when I am on the bike approaching walkers on the canal tow path how blowing the horn can make people jump, a comment like lovely day as approaching I find better than a horn.

But we have got use to beep, beep, beep meaning a vehicle is reversing, and the sound of an engine, this car is also super silent, even less noise to an electric car, specially at low speed, may be we needs same rules as railway, blow whistle before starting and at every junction.

 

[Avocet]

Traditionally the railway engines here would have had bells and whistles, the bell would be rung all the time it was travelling through the street, View attachment 281388 since it no longer goes through the streets the bell has gone, when the flying scotchman went to USA it had to have a bell added as in USA many railways are unfenced.

We have seen in this country environmental friendly reversing bleepers which monitor the back ground noise and adjust their volume to match back ground noise.

However the idea of twin horns seems to be just to make them louder, not to adjust how much noise, and I know with cars sounding horns as they pass me on a bike, or when I am on the bike approaching walkers on the canal tow path how blowing the horn can make people jump, a comment like lovely day as approaching I find better than a horn.

But we have got use to beep, beep, beep meaning a vehicle is reversing, and the sound of an engine, this car View attachment 281389 is also super silent, even less noise to an electric car, specially at low speed, may be we needs same rules as railway, blow whistle before starting and at every junction.

It's always a fine line between "warning" and "nuisance". I reckon that steam car could make enough racket if its safety valve opened!

 

[ericmark]

I reckon that steam car could make enough racket if its safety valve opened!

I think the steam car uses a flash boiler, so safety valve would not normally open.

 

[JohnD]

I was talking to someone from Rolls Royce yesterday, who was praising their new electric car. I asked what noise it made, and she said none. I thought electric cars had to make a noise at low speed?

When I used to drive RRs, the tyres made a noise, perhaps due to the weight on them.

Apparently they still fit the special noisy clock.

 

[Avocet]

I was talking to someone from Rolls Royce yesterday, who was praising their new electric car. I asked what noise it made, and she said none. I thought electric cars had to make a noise at low speed?

When I used to drive RRs, the tyres made a noise, perhaps due to the weight on them.

Apparently they still fit the special noisy clock.

You're absolutely right. They DO now have to make an artificial noise at low speed. And yes, all tyres make a noise and large, heavily-loaded tyres make a noise too. Above about 30 or 40, (and assuming a constant throttle opening rather than hard acceleration), the tyre noise starts to be louder than the engine noise on most cars.