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Clapping hands as loud as Helicopter

This Guy

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This Guy
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Mar 24, 2006
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"Zhang Quan, 70, of Chongqing city can clap his hands almost as loud as the sound of helicopter blades.

Recently his clapping was measured by local environmental protection officials as reaching 107 decibels. This is only slightly less loud than the 110 decibels reached by a helicopter."

This is hard to believe. Heard it on the radio this morning, and found this link when I got home -

http://www.weirdasianews.com/2007/07/22/mans-clap-as-loud-as-a-helicopter/

That's bloody loud! (no, I'm not British, but I think "bloody" passes the new rule 8 guidelines, and my first choice didn't ;))

It would seem to me, that to produce noise that loud, you would have to really hit your hands together HARD! I just can't imagine someone doing this! I'd love to see a video of him doing it (clapping that is. Not whatever IT your thinking of! ;))

Debated putting this in current events, but since it deals with sound I figured science was a better area for it.

No question, just thought I'd share this amazing bit of info :)
 
This Guy said:
"Zhang Quan, 70, of Chongqing city can clap his hands almost as loud as the sound of helicopter blades.

Recently his clapping was measured by local environmental protection officials as reaching 107 decibels. This is only slightly less loud than the 110 decibels reached by a helicopter."

This is hard to believe. Heard it on the radio this morning, and found this link when I got home -

http://www.weirdasianews.com/2007/07/22/mans-clap-as-loud-as-a-helicopter/

That's bloody loud! (no, I'm not British, but I think "bloody" passes the new rule 8 guidelines, and my first choice didn't ;))

It would seem to me, that to produce noise that loud, you would have to really hit your hands together HARD! I just can't imagine someone doing this! I'd love to see a video of him doing it (clapping that is. Not whatever IT your thinking of! ;))

Debated putting this in current events, but since it deals with sound I figured science was a better area for it.

No question, just thought I'd share this amazing bit of info :)
Click to expand...

The question to ask is "How far was the microphone from the helicopter, and how far was the microphone from the guy clapping his hands?"

Sound levels drop with distance. Unless you specify the mic to source distances, there's no real comparison.
 
MortFurd said:
The question to ask is "How far was the microphone from the helicopter, and how far was the microphone from the guy clapping his hands?"

Sound levels drop with distance. Unless you specify the mic to source distances, there's no real comparison.
Click to expand...

Good point!

I assumed all things were equal. But that is not stated anywhere in the article.
 
MortFurd said:
The question to ask is "How far was the microphone from the helicopter, and how far was the microphone from the guy clapping his hands?"

Sound levels drop with distance. Unless you specify the mic to source distances, there's no real comparison.
Click to expand...
My first thought too! Its certainly possible to clap hands near someones ear hard enough so that its painfully loud.
 
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That's the funny thing about sound. There's very little energy in sound, especially in a short burst like a clap. Balloons popping can apparently reach 157 dB, roughly on par with jet engines.
 
If I remember correctly, when using amplifiers, to go up 3 dB you have to use twice the amount of energy, so there is a significant difference from 107 to 110 dB.
 
Twice the power, yes, but twice a tiny amount is still tiny. But first, a note about acoustic dB.

There are at least 3 common uses of dB in acoustics (plus modifications from weighting functions, in order to simulate hearing). There's the pressure (Pascals), the intensity (Watts per square metre), and the source power (Watts). Pressure and intensity are both at the receiver, so they decrease as distance increases. Power is calculated as the total acoustic power emitted by the source, so it is constant regardless of how far the receiver is. Hopefully that's what the article is using.

Power dB is relative to 10−12 Watts. At 110 dB, that's only 0.1 W, and 107dB is 0.05W. Offhand, I'd guess a clap lasts maybe a fifth of a second, and that 107dB is the peak, not the average loudness. Still, if it was the average, that would be
0.05 W * 0.2 s = 0.01 J.

If his hands mass to half a kilogram, and are moving at 2 m/s, they have kinetic energy equal to
0.5 * 0.5 kg * (2m/s)2 = 1 J

Which means he would only need to be 1% efficient at turning hand kinetic energy into acoustic energy to be that loud. And that is why I believe this story is possible.
 
the smallest increment that one can differentiate is typically 1 to 3 dB. adding to dilb's post, 1 acoustic watt distributed over a sphere (with 1 m radius) is about 112 dB.

if the guy clapped in a room, then there are variables like room size and absorption. this is likely a case of a journalist just writing whatever sells.
 
Isn't *anyone's* hand clapping louder than "Super Seecrit Whisper Mode (tm)" on Black Ops helicopters?
 
MortFurd said:
The question to ask is "How far was the microphone from the helicopter, and how far was the microphone from the guy clapping his hands?"

Sound levels drop with distance. Unless you specify the mic to source distances, there's no real comparison.
Click to expand...
A good point, without a true reference the comparison means little.

Paul

:) :) :)
 
MortFurd said:
The question to ask is "How far was the microphone from the helicopter, and how far was the microphone from the guy clapping his hands?"

Sound levels drop with distance. Unless you specify the mic to source distances, there's no real comparison.
Click to expand...

Measuring noise levels can be very frustrating. If you want to measure impulse noise, then a meter from Radio Shack is not going to cut it. Microphone response time, temperature, humidity and position of the mic all play a part. There are some good posts and articles on http://www.silencertests.com about measuring muzzle blast from firearms, suppressed and unsuppressed.

Edited to add; From the link, "Recently his clapping was measured by local environmental protection officials as reaching 107 decibels. This is only slightly less loud than the 110 decibels reached by a helicopter." A increase in 3 decibels equals double the noise. His clapping is only half as loud as a helicopter.

Ranb
 
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But at what distance from the sources.............

Paul

:) :) :)
 
Distance is important as most have mentioned already, when I was into car audio I used to look at specs all the time for different speakers. And it always amazed me that a sub-woofer could produce 80+db at 1 watt, but they were always measured at 1 foot from the speaker.
 
vexed said:
Distance is important as most have mentioned already, when I was into car audio I used to look at specs all the time for different speakers. And it always amazed me that a sub-woofer could produce 80+db at 1 watt, but they were always measured at 1 foot from the speaker.
Click to expand...
The norm for that is 1 meter as you know.

Paul

:) :) :)
 
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