Is it possible I heard Big Ben?

[Mad Doug Biker]

i believe you

not the same thing but occasionally on clear evenings in the summer when the wind is blowing in the right direction, you can hear the chug chug from trains from a train station that is a few miles away. IT COULD HAPPEN!!!!

Chug chug?? what is the station on a preserved line and it is steam locos?? (yes, I know deisels can make a noise similar).

Actually, hearing trains from quite a distance away isn't unusual, and certainly some of the older types of diesels out there can be heard thrashing away several miles off at times.
I could practically set my watch from the southbound West Highland Sleeper when it used to be hauled by a class 37, seeing as it clearly could be heard from my house. The class 67s are all quiet and boring in comparison and I rarely hear the train now.

And just yesterday, I was walking over an old road over the hills between Dumbarton/Renton and Cardross (the Kipperoch Road), and even though they were several miles distant at times, I could clearly hear the horns of the trains as they passed the level crossings along there towards Helensburgh.
I was seeing if the Kipperoch road would be suitable for cycling over in a circular route between it and Carman Hill you see, and it seems reasonable enough, save for 3 farm gates, seeing as there are several farms up there and Cows wandering about.

 

[Aperitif]

The actual spherical propagation relationship is based upon 20*log(r2/r1) and if we assume that the reference distance r1 is 1m and the receiver r2 is at a distance of 300,000m then the distance attenuation in moving from 1m to roughly 200 miles is 110dB. Atmospheric absorption is very significant over such a long distance but varies according to frequency. The bell known as Big Ben has a dominant frequency of 440Hz and if we assume a temperature of 5 degrees Celcius, 20% relative humidity (it's low in winter), and pressure of 101.325 kPa, atmospheric absorption runs to 0.00351 dB per metre, which equates to 1053dB over 300,000m. Total calculated attenuation is therefore 1163dB, extremely high but slightly less than "several thousand dB". However, this is very much a crude approximation, probably nonsensical, as other atmospheric and environment effects will be highly significant; to do a full calculation would take more time than I'm prepared to devote and not give any better result.

So, could you hear Big Ben at 160 miles? Highly unlikely but I'm always reluctant to say something isn't possible. Very loud sounds can be heard at staggering distances primarily due to refraction effects, anyone with nothing better to do could have a look at http://www.flyoaklan..._atmosphere.pdf an excellent 2006 article on the subject by Tom Gabrielson of Penn State University.

Gordon

Brilliant! You need to go on a nice long summer's evening ride with TimO, Gordon - you'll get on like a house on fire. We will ride behind and bathe in the glow - CycleChat's green kryptoniteers!