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B Finding the acoustic point in a valley

  1. Jan 30, 2017 #1
    Hello,

    I have a practical problem, I'd like to find the "best" spot to hear sounds in a valley (forgive me if "acoustic point" isn't an appropriate term, I just couldn't come up with anything better and scrolling an acoustics text didn't help), or at least a non-blind spot (one which instead focuses on a relatively limited sector), to listen to as many sounds as possible. I am not sure if this could/would coincide with an echoing point.

    I know this probably doesn't have have a precise answer or integral formula since factors such as wind speed, air humidity, temperature, ground elevation microtopography and tree cover would act as infinite variables, however I'd at least see what you do think and which tips I should follow to avoid the "worst" hearing spots.

    I have elevation data of 30m resolution and topographic ground measurements, I know the tree cover from aerial pictures.

    I drew a really crude sketch which if forgiven for my lack of drawing skills, could somehow better explain if I should look for a shallow point, an elevated one on the side, a really elevated one on the side or an elevated one in the middle (sketched just 3 example points since I couldn't clearly show supposed elevation differencies among them).

    Edit: I forgot to add that most sounds would probably be randomly scattered both horizontally and vertically within 10m from soil level, possibly more densely distributed around a fixed point in the valley and mostly in the lower parts of the valley, within half of Hmax (maximum mountains height).

    I'd consider "best" a point in which I'd hear most of them at the same time (even if obviously at different intensities due to various distance among them and me).


    Thank you

    Allison

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    Last edited: Jan 30, 2017
  2. jcsd
  3. Jan 30, 2017 #2

    anorlunda

    Staff: Mentor

    Wow, that's not a simple problem. The answer would be very sensitive to the exact shape of the terrain and its texture and cover.

    Even the question of "best" is not easy to define. Echos provide more volume, but the time shifting might make the sound worse, not better. You'll have to define "best"
     
  4. Jan 30, 2017 #3
    The real question is, where is the sound coming from? If it's from straight above, really high up, I would think all points are equally good (with slight preference to high points as they are closer to the source).
    If the source is outside the mountain range but close to the ground, there's a chance only the bordering areas will hear anything.
    If the source is somewhere inside the mountains, direct line of sight will hear a lot, whereas other places might only hear reflections.
     
  5. Jan 30, 2017 #4
    Thank you for your replies.

    You're right, I forgot to add that most sounds would probably be randomly scattered within 10m from soil level, possibly centered around a fixed point in the valley and they would be prevalently distributed in the lower parts of the valley, within half of Hmax (maximum mountains height).

    I'd consider "best" a point in which I'd hear most of them at the same time (even if obviously at different intensities due to various distance among them and me).

    Thank you

    Allison
     
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