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Asked by macCombiLJD to Claire, Ryan, Mako on 25 Jun 2015.
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Ryan Cheale answered on 25 Jun 2015:
I’m going to have a think about this one and get back to you! This is areally good question and I have an idea of an answer 🙂
Okay so obviously as claire said you can’t shout to china BUT I wanted to see how you’d manage it if you could with technology as that’s more fun, right?So the limit of human hearing is like I= 10^-12W/m^2 at 1000Hz. There’s an acoustic equation which is d=(X/(4*pi*I))^(1/2) where X is your output sound.
China is 6500 miles away (crikey! ) which is 10,460,736m.
Lets rearrange our equation to make X our subject
d^2 * 4 * pi * I = X
So the power we need is (10,460,736)^2 * 4 * 3.1415 * 10^-12 = 13751W now this isn’t input watts as you can have rock concerts at 400,000W which you can’t hear from china
So lets hook you shouting up to a speaker, you shout with the force of 0.05 acoustic watts (tiny!) So we need to increase your shout by 700 times, but sound falls off a 1/x^2 so we need 4 times so a 2800 increase.
I’m merely guessing now, but i’d say you’d need a line of around 1000 top end megaphones and I don’t think that comes close as you’re pushing the limits of well sound! You’d also need to keep the intensity up before the sound diffused
For some perspective krakotoa which went off in the 1800s could be heard from 3000 miles away, so you’d have to be four times as loud at least.
Wasn’t quite the answer I wanted to give butt I ran out of time 🙁
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Claire Bryer answered on 25 Jun 2015:
Unfortunately without the help of technology no one in China will hear you shout! If you use a phone or the Internet I’m sure you can make your voice heard!
Comments
macCombiLJD commented on :
HA! Thanx guys!
Ryan commented on :
Okay so obviously as claire said you can’t shout to china BUT I wanted to see how you’d manage it if you could with technology as that’s more fun, right?
So the limit of human hearing is like I= 10^-12W/m^2 at 1000Hz. There’s an acoustic equation which is d=(X/(4*pi*I))^(1/2) where X is your output sound.
China is 6500 miles away (crikey! ) which is 10,460,736m.
Lets rearrange our equation to make X our subject
d^2 * 4 * pi * I = X
So the power we need is (10,460,736)^2 * 4 * 3.1415 * 10^-12 = 13751W now this isn’t input watts as you can have rock concerts at 400,000W which you can’t hear from china
So lets hook you shouting up to a speaker, you shout with the force of 0.05 acoustic watts (tiny!) So we need to increase your shout by 700 times, but sound falls off a 1/x^2 so we need 4 times so a 2800 increase.
I’m merely guessing now, but i’d say you’d need a line of around 1000 top end megaphones and I don’t think that comes close as you’re pushing the limits of well sound! You’d also need to keep the intensity up before the sound diffused
For some perspective krakotoa which went off in the 1800s could be heard from 3000 miles away, so you’d have to be four times as loud at least.
Wasn’t quite the answer I wanted to give butt I ran out of time 🙁
Ryan commented on :
Okay so obviously as claire said you can’t shout to china BUT I wanted to see how you’d manage it if you could with technology as that’s more fun, right?
So the limit of human hearing is like I= 10^-12W/m^2 at 1000Hz. There’s an acoustic equation which is d=(X/(4*pi*I))^(1/2) where X is your output sound.
China is 6500 miles away (crikey! ) which is 10,460,736m.
Lets rearrange our equation to make X our subject
d^2 * 4 * pi * I = X
So the power we need is (10,460,736)^2 * 4 * 3.1415 * 10^-12 = 13751W now this isn’t input watts as you can have rock concerts at 400,000W which you can’t hear from china
So lets hook you shouting up to a speaker, you shout with the force of 0.05 acoustic watts (tiny!) So we need to increase your shout by 700 times, but sound falls off a 1/x^2 so we need 4 times so a 2800 increase.
I’m merely guessing now, but i’d say you’d need a line of around 1000 top end megaphones and I don’t think that comes close as you’re pushing the limits of well sound! You’d also need to keep the intensity up before the sound diffused
For some perspective krakotoa which went off in the 1800s could be heard from 3000 miles away, so you’d have to be four times as loud at least.
Wasn’t quite the answer I wanted to give butt I ran out of time 🙁
0 Like?