How far away can you hear a speeder/drifter?

[Chozza]

Lying in bed a few nights ago , I could clearly hear the sound of two cars being drifted around a nearby roundabout,

The roundabout is 1.92 km from my house across open fields and there it was 11:30 so there was little background noise.

In the summer i can hear fast movers on the dual carriage way ( about 1km ) if its a clear night ( and its pretty easy to tell the very fast from normal speeders)

This got me thinking .. if its a quiet night do traffic police just park up and listen ? and can they use this intelligence to target the speeders and the roundabout drifters.

or are they just too busy/too few to bother nowadays ?

[grumpy52]

Old police trick was to sit with the windows of the patrol car open when parked up at night .
Having marshalled out on night rallies we could hear the first car from about 2 miles out . A couple of miles is fairly normal over clear ground .
It has been reported that with the wind in the right direction that race noise from Lydden can be heard in Folkestone. Mostly because of them being at each end of a valley .
On clear evenings we used to be able to hear the hovercraft leaving Dover , some 8 miles away .

[BertBert]

grumpy52 said:

Old police trick was to sit with the windows of the patrol car open when parked up at night .

My word, there used to be some smart coppers about.

[rxe]

Depends on the exhaust I would think. We hear the guys on sport bikes spanking it down our local straight. I’ve tried it in a variety of cars - we’re about a mile away. The wife can hear me giving it full beans in an Alfa GT 3.2 with a fairly raucous exhaust, can’t hear me in an Alfa GTA with the same engine and a quiet exhaust. We never hear any tyre noise.

[Greendubber]

BertBert said:

grumpy52 said:

Old police trick was to sit with the windows of the patrol car open when parked up at night .

My word, there used to be some smart coppers about.

There still are.

There are places I work where you can hear the cars coming before you see them. Usually two dheads in elderly Honda Civics with asbo exhausts going head to head up the dual carriageway.

[Berkshire bred]

The a4 runs 3-4 miles from my house as the crow flies. On a still quiet night you can hear cars and bikes flying along there. I have also heard the a4 from the top of combe jibbet, that has to be 5 miles.

[ashleyman]

Not drifting but can hear people with loud exhausts, no idea if they’re speeding or not. The road they do it on is about 1km from my place and with the window open you sometimes make out car. Lots of bikes. A couple GTR’s, a huracan once (could tell by the pops and crackles as he lift off) often hear the guys bouncing their cars off a limiter - probably VTECs or MK5 GTIs.

[Bigends]

This was common practice. Its not just cars you can hear in the dead of night, you'd also pick up the sounds of people talking and walking and running quite some distance away.

[Evolved]

BertBert said:

grumpy52 said:

Old police trick was to sit with the windows of the patrol car open when parked up at night .

My word, there used to be some smart coppers about.

[Crackie]

Chozza said:

Lying in bed a few nights ago , I could clearly hear the sound of two cars being drifted around a nearby roundabout,

The roundabout is 1.92 km from my house across open fields and there it was 11:30 so there was little background noise.

In the summer i can hear fast movers on the dual carriage way ( about 1km ) if its a clear night ( and its pretty easy to tell the very fast from normal speeders)

This got me thinking .. if its a quiet night do traffic police just park up and listen ? and can they use this intelligence to target the speeders and the roundabout drifters.

or are they just too busy/too few to bother nowadays ?

http://sciencewows.ie/blog/does-sound-travel-faster-in-warm-or-cold-air/

[Higgs boson]

Back in the dark ages, I could hear a friend change down for a corner that was a smidgen over 3 miles away from where I was standing.
He was riding a K4 250 Honda with straight-through pipes, though.

[FWIW]

Chozza said:

Lying in bed a few nights ago , I could clearly hear the sound of two cars being drifted around a nearby roundabout,

The roundabout is 1.92 km from my house across open fields and there it was 11:30 so there was little background noise.

In the summer i can hear fast movers on the dual carriage way ( about 1km ) if its a clear night ( and its pretty easy to tell the very fast from normal speeders)

This got me thinking .. if its a quiet night do traffic police just park up and listen ? and can they use this intelligence to target the speeders and the roundabout drifters.

or are they just too busy/too few to bother nowadays ?

This is completely dependent upon exhaust noise rather than speed.

[simoid]

I’ve been golfing and heard the superbikes at knockhill: must be a good 12-15 miles as the crow flies. Presumably a slightly different kettle of fish as they aren’t road legal for noise production.

A lot will depend on wind direction and any barriers to the sound such as foliage next to the originator of the sound.

[V8 Fettler]

It's generally traditional at this point to refer to the noisy DKW bike from a few years ago:



Around 35 miles, although not speeding.

[Mr E]

grumpy52 said:

On clear evenings we used to be able to hear the hovercraft leaving Dover , some 8 miles away .

To be honest, you could probably hear one of those from the ISS.

[BugLebowski]

I'm not sure how possible it is to hear someone speeding. There is a guy who lives somewhere near me with an IS200 that sounds as if he is close to breaking the sound barrier even at sedate speeds.

[Roofless Toothless]

For those who know the eastern fringes of glorious Essex, there is a country road that runs out from Southend to Barling, which at one stage has a series of 90 degree bends around the corners of fields.

When I had my Caterhams it was a good place to 'experiment' with the cornering power of the cars. One day, after exiting this series of bends in low gear and a fair amount of tyre noise I came suddenly upon a marked police car and an officer standing by it at the roadside. He obviously had been awaiting my telegraphed appearance for some time. Of course, I flashed him an ingratiating grin. He responded with a