How far away from a busy road can you hear the noise caused by traffic on that road? Does weather affect the distance? I think I remember reading years ago that if you can hear a train whistle in a place where you usually cannot, it's a sign it's going to rain.
How far away from a busy road can you hear the noise caused by traffic on that road? Does weather affect the distance? I think I remember reading years ago that if you can hear a train whistle in a place where you usually cannot, it's a sign it's going to rain.
Anything that affects the density and composition of the intermediate air will affect the relative distance and clarity the sound travels. It will be subjective to the listener as such.
How far away from a busy road can you hear the noise caused by traffic on that road?
That's going to depend on a lot of factors.
The type of traffic, semi trucks make more noise than cars for example.
The terrain makes a difference physical barriers will block and or mute noise from the road. That's why the started putting up tall walls on the interstate highways where they pass close to residential neighborhoods.
Yes, the weather makes a difference. Sound will travel farther in a denser medium. So air pressure and humidity will make a difference.
Yes, the weather makes a difference. Sound will travel farther in a denser medium. So air pressure and humidity will make a difference.
The distance sound travels doesn't change regardless of the medium. The amount of attenuation and absorption is another thing entirely. That is before we get to diffraction and reflection.
Sound is a mechanical wave. Compression on the front side, rarefraction on the backside. Under the right conditions, it can be literally bounced/diffracted over you or around you, or conversely, sent straight to you by the same.
https://www.acs.psu.edu/drussell/Demos/refract/refract.html
The terrain makes a difference
2 different Civil-War battles were fought while one side's commanding general was ignorant that they were going on because he was in a "noise shadow" and didn't hear the battle.
https://acoustics.org/pressroom/httpdocs/136th/ross.htm
Some more information on that subject.
if you can hear a train whistle in a place where you usually cannot, it's a sign it's going to rain.
Around here, it's more that it's now raining, or has just rained but still overcast. That's the only time I hear the freight line that goes through downtown.
I live 2 miles east of a north/south interstate with exit. I can hear trucks, probably not cars. Variables: Central Indiana, mostly flat, farm fields, some trees in field fence rows, wind mostly from the west. Interstate bridges over city street (exit), just south of exit, southbound narrows from 3 to 2 lanes, north expand 2 lanes to 3. Now much noise is due to the bridge? How much due to jocky-ing for position due to 2-3 lanes? How much due to on/off ramp activity?
Decibel? Dont know. I'm aware of the noise, but can tune it out.
Variables: Central Indiana, mostly flat, farm fields, some trees in field fence rows, wind mostly from the west
That would be why Rose-Hulman put out their famous 'Ski Terre Haute' poster many years ago.
I'm originally from the just north of there (aka Covered Bridge County). Hopefully when you say Central Indiana, you're not referring the true heart of darkness, Kokomo. :)
Indiana, where Russiaville is pronounced Roosyaville, Galveston is three words - Gal vest on, and Versailles is Ver sails.
No, just enough south of Indy to avoid the traffic!
There are a few of those uniquely pronounced names in Indiana!
How far the noise carries will vary a lot depending on many factors, all of which can affect the amount of noise made by an individual vehicle or all of the vehicle. Topography like being on a flat or in a depression, roadside construction like berms and fences, roadside vegetation like trees and bushes, the type of road surface, the speed of the vehicle, the material the vehicle tyres are made off, and the amount of traffic all affect the road noise regardless of the distance. When you get more than a few feet / metres from the road other factors like the humidity, air pressure, other weather factors, time of day, actual distance, and everything else between you and the road affect the level of the noise you hear.
Some other factors worth taking into account are background noise and the hearing ability of the listener. The human brain has an amazing ability to filter out noise to such an extent that you are basically subconsciously ignoring it.
You might not hear road noise because something closer is louder, machinery, farm/pet animals etc, and when they stop, you suddenly notice the noise of the road.
As previously mentioned, the hearing ability of the listener plays an important part. Some people are simply deaf, some people have acute hearing when it comes to high frequency noise, for some it's low frequency.
I suffer from tinnitus, yet can hear the bats outside the house at night squeaking away like mad, and to be honest, it's fucking annoying... Even more so since they are supposed to be above the threshold of human hearing.
yet can hear the bats outside the house at night squeaking away like mad, and to be honest, it's fucking annoying... Even more so since they are supposed to be above the threshold of human hearing.
It's more frequencies than decibel levels. Bats are very high frequency and low energy/decibels. For humans, it's the upper range of frequency that normally can be heard. However most literature for that is based on statistical models. Be glad it's not on the lower end of the spectrum, you'd be hard pressed to get a moments peace anywhere around human activity if that were the case.
How far away from a busy road can you hear the noise caused by traffic on that road? Does weather affect the distance?
Today I can't hear traffic on a nearby motorway (about 2 miles, and the motorway has sound-muffling barriers). The conditions are extremely moist but not raining - I'd describe it as a medium-density mist.
Usually I can hear the traffic quite clearly in the background, but it would be drowned out by building works, revving engines etc.
AJ
I was tangentially involved with environmental impact assessment of a planned highway (Europe, two lanes each direction, 130km/h max allowed speed) and they considered 1200 meters each side (~ 3/4 mi) the zone of the noise pollution worth considering for mitigation.
From own experience, at low noise background over flat land, mixed but less than 30% tree cover, it's about a mile where light wind in trees would start to outcompete the sound of tires on asphalt of moderate but constant 90-100km/h mixed traffic. Some semis can be slightly louder, and definitely certain engines feeling special. Bar those, at distance the highway becomes a constant almost fixed noise easily filtered out and ignored. How sensitive to it people are might be individual, and sometimes more psychological than physical.
I live ~3.4 miles from country's busiest railway where it slows trough a town, and the heaviest cargo trains can be heard sometimes but not other times, something that became more frequent once certain plot of forest was cut down. Sometimes I can hear even the electric passenger trains braking and accelerating in and out of the station at said town.
2.5 miles, measured here for both freeway and train horns.
Train horn (always the same locomotive, there's only one which makes the daily trip) is sometimes louder than other times, but I haven't paid much attention to what weather conditions affect that.
is sometimes louder than other times
Could the change in volume also be due to the direction the train is traveling ?
Near me I can always hear the west bound train sounding horns as those trains are traveling towards me but it is very rare to hear the east bound trains sounding horns as they are past me and traveling away from me.
Near me I can always hear the west bound train sounding horns as those trains are traveling towards me but it is very rare to hear the east bound trains sounding horns as they are past me and traveling away from me
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Wavelength change due to doppler effect. The actual amplitude will remain unaffected. The perceived amplitude can change (get louder) when the frequency reaches the listeners peak response. The latter point will be different for each individual. Coming to you, the frequency increases, moving away, it decreases.
https://www.acs.psu.edu/drussell/Demos/doppler/doppler.html
Near me I can always hear the west bound train sounding horns as those trains are traveling towards me but it is very rare to hear the east bound trains sounding horns as they are past me and traveling away from me.
A large part of that is due to the way the train horns are designed and mounted. The train horn is shaped and mounted to push the sound out in front of the train, which it does very well. The result is the majority of the energy and sound goes out as a wave in front of the train and only a very small fraction ends up going to the sides and behind the train. This is akin to how well you hear someone when they go from standing in front of you while talking to you then they continue talking when they turn around and walk away, the sound level goes down despite them staying at the same volume. Then you have Doppler effect coming into play as well, along with the other external factors like echoes and the absorption of the sound energy by the things in between the train and you.
Wavelength change due to doppler effect. The actual amplitude will remain unaffected. The perceived amplitude can change (get louder) when the frequency reaches the listeners peak response. The latter point will be different for each individual. Coming to you, the frequency increases, moving away, it decreases.
https://www.acs.psu.edu/drussell/Demos/doppler/doppler.html
Yes I understand this what I was reffering to and maybe not explaning very well is that I have a rail crossing that is located east of me so when there are west bound trains that sound their horns it is coming towards me in my direction and yet the east bound trains are past me and sounding their horns pointing and going away from me. You can get the same thing from speakers if you are in front of the speaker they are easier to hear than if you are behind them.
