(The music was) Faraway, so close

November 22, 2010 12:58 PM

So I was listening to the sound check for the upcoming U2 concert yesterday from my house, which is just over 2km from the stadium. I could tell that the sound was immensely loud at the source even though it wasn't rattling my windows or anything. How did I know it was a huge sound at a distance rather than coming from nearby? What auditory cues tell us this?
posted by Miss Otis' Egrets to Science & Nature (8 answers total)

My guess is: you deduced it, rather than sensed it.

It's a little hard to separate our cognitive processes from our lower-order sensory inputs. When my computer speakers play dog barks, my dog will get up and go to the window - even when he is between the window and the speakers. He knows there is no dog sitting on the speakers, so it must be outside.
posted by IAmBroom at 1:03 PM on November 22, 2010

the echo pattern was probably completely different and distinct
posted by facetious at 1:05 PM on November 22, 2010

It is strange that I had the same experience with a U2 concert, which was 2 miles from my house.

From inside the house, it seemed that it was the neighbors' stereo being too loud, but outside, it was more garbled and obviously U2. The sound "skips" along the ground, and gets less clear, and that may be a clue about how far it is.
posted by Danf at 1:11 PM on November 22, 2010

Your ears will pick up cues that the sound is more diffuse, bouncing off of other sources rather than your room. While a stereo system in your house is great for localizing sources within that stereo spectrum, you'll notice that there probably more points of reflection caused by buildings and houses.

Also, bass frequencies in general will travel farther than higher frequencies. The impact of the bass will be more visceral than your home stereo, being backed by concert-level amplification.

I also live about that far from a concert venue and also notice that clarity in the midrange and higher will come and go, depending on wind shifts.

Also, WOOOOO!!!! CONCERT!!!!!
posted by toastchee at 1:20 PM on November 22, 2010

The "Sound Localization" Wikipedia article is pretty good. Here's the part about distance.
posted by unknowncommand at 1:27 PM on November 22, 2010

All sorts of factors play into how well sound travels. Air density, smog, wind direction, humidity, topography all can make sound travel far or dampen sound. In your case, it may not have been that the sound was loud as much as it was a perfect set of circumstances which allowed the sound to travel further than it normally would. In short, there aren't too many cues unless you know the environment well. Echoes are the best cues but those too, vary by environment.
posted by JJ86 at 2:02 PM on November 22, 2010

One thing I don't see mentioned above is that the further the sound is away from you, the less its relative volume will change as you move slightly further away and towards it. If you're 2 km away from a sound source and walk 10 metres in each direction, you've only changed your relative distance to the sound source by a very small margin. And so, the overall decibel level reaching your ears will be virtually identical.

It'd be nice if a physicist could confirm what I wrote above as I'm just basing this on my own experience.

If it was your neighbour's house blasting a stereo (even with booming bass), the noise level would change more dramatically even with just a small movement on your part. As well, if you turn your head, the U2 concert will sound almost identical as it is basically a wash of sound, but your neighbour's sound source would be more directional.

Apart from these things, the relative loudness of the bass sounds, as well as the overall diffuseness of the overall sound can give you some clues to its distance.
posted by fantasticninety at 4:59 PM on November 22, 2010

High frequency is attenuated more over distance than low frequency is. Also, the sound travels and bounces around on all sorts of objects (even the atmosphere, I believe). Therefore, if the concert is 2 miles away it will be all bass with almost no treble, and it will be muffled. If it were next to your house, you would be able to clearly hear the whole gamut of sounds. A similar situation is with lightning: When it's far away, all you hear is the rumble and boom, but when it's nearby you can hear the crack.
posted by Simon Barclay at 6:29 PM on November 22, 2010