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Hey all - pretty new here and was wondering whether somebody could point me to a study or information that discusses the relationship between the degradation of sound quality (and volume) and external factors in an outdoors environment. I'm interested in what the impact of more plans, or a body of water would be on sound quality and volume for example. Don't care whether it's a pretty academic discussion, just interested in the topic.
I deal with loudspeakers, sound out doors at distances at work and can offer an explanation.
If you had a single very small driver, it would radiate as a "point source" and project a portion of a sphere forward. As you move away, the loudness falls off at the "inverse square law" or -6dB every time you double the distance. Also at high frequencies, there is air absorption which attenuates the high frequencies although at a hundred feet or less it is insignificant (a calculator below)
The problem is that if one has more than one source in a loudspeaker, one has an interference pattern when they are both radiating and in loudspeakers, one manifestation is that the spectral balance and loudness changes with distance.
On a larger scale, this inherent multi-source interference pattern is what gives concert line arrays "that sound", variable spectrum based on location and a limited working distance, it isn't a loudness issue, it's more of a spectral and intelligibility issues.
So, in general outdoors when the weather is good, is a more benign environment for listening, especially at the scale of home stereo as there are NO room effects and it is surprising what one can do outdoors even at the scale of a football stadium.
What scale are you dealing with?
Wow - thanks for the detailed reply, also to the other posters. In terms of scale I'm really just thinking "average backyard". I have no doubt I can find a setup that would sound great for my purposes, I'm curious about a discussion I had with a friend about outdoor environmental impacts. Assuming the speakers are a set variable, would a more "bushy" environment dampen the sound volume (break or absorb the waves) and would a pool for example cause sound to travel further?
I get that the actual impact may be very little to the untrained ear like mine, but in theory...?
Well, heck, Tom, I was hoping/expecting that you'd get into a little about temperature, humidity, air pressure, temperature inversions, bodies of water, etc.
tomservo knows vastly more about this subject than me, but I might be able to add a (hopefully) interesting little note. Several decades ago when I was much more energetic than now I had a pair of good 3 way d'Appolito towers with all Dynaudio drivers I had built for myself. Being aware of all sorts room effects problems I wondered how my speakers would sound If I set them up way out in my yard far away from reflective surfaces except the ground and an occasional tree trunk. Once I got toe in and listening distance optimized and got over missing various room resonances the sound was wonderful. Rather than speaking of outdoor placement degrading the sound I think of it as being a placement that improves the sound very much.
One caveat to the above is that the speakers were actively biamplified, and if I remember correctly I boosted the bass some in the outdoor setting.
The only acoustic down side to being outside is you might have to add a bit more bass but begin free of room effects can be wonderful!
It's been a great weekend and I thank you for the amusing play on words.
Seems to me small speakers will sound even smaller when taken outdoors.
More than the environments affect on the wear I would put any speaker you like in the environment and see how they sound. You'll see things like if the neighbors will here and how much as well as sound. Speakers out in the yard pointing to the house is generally better than the other way around.
Focus on how they will sound and other logistic issues. not so much on which product you will use. Regular speakers you bring in and out will return the best value by far.
Of course we know nothing about the environment but it is outdoors.
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
I have a pair of Yamaha outdoor speakers that are maybe 10 years old. Initially, they were in a protected spot. After we moved and built a trellis patio cover, they've been sitting on top of it, totally exposed for 4 or 5 years. Yeah, the black grills could use some rustoleum paint, not that anyone can see them.
As far as sound, I'm surprised. These were a model with 6.5" woofers and the sound is exceptional and can be played plenty loud enough to annoy all the neighbors before they'd hit the wall on being over driven.
Update: I just asked my son and his buddies that are playing beer pong out back, and they agreed, sounds great. Both of us were also amazed that they even work after all the poundings of rain and sun they're endured over the years.
"Acoustical Designing In Architecture" by Knudson and Harris, chapter 5.
Possibly also "Master Handbook Of Acoustics" by F. Alton Everest.
Also search the Audio Engineering Society (aes.org) for pertinent words/phrases. Also maybe the Acoustical Society of America, but they get into a lot of stuff, and it may be too much bother for what you want.
Edit: Also, our good buddy tomservo will likely have some recommended reading and personal knowledge, since that's one of his primary areas of expertise.
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