How does a layman easily work out the inverse distance law of sound waves?
Say someone is yelling at 100 or 110 decibels, how loud is that at 50, 75 or 100 mtrs?
This…
“The sound level will decrease by 6 dB every time
the source to the listener’s distance is doubled.”
Doesn’t make sense.
Ta.
http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/invsqs.html
might help.
http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/invsqs.html
——————————————-
Yeah but no.
I get twice the distance is 4 times the area… but not a quarter of decibels. Are they like earthquakes?
With the mathamagic provided it gives a starting source of 100 decibels and at 100 mtrs…90 dB
Mr Ironic said:
http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/invsqs.html
——————————————-Yeah but no.
I get twice the distance is 4 times the area… but not a quarter of decibels. Are they like earthquakes?
With the mathamagic provided it gives a starting source of 100 decibels and at 100 mtrs…90 dB
A 6 dB drop is a quartering.
/* How does a layman easily work out the inverse distance law of sound waves? */
/*
“The sound level will decrease by 6 dB every time
the source to the listener’s distance is doubled.”
*/
Inverse square => double distance, one-quarter intensity.
Logarithmic scale for bel => 10 times intensity for each bel.
10 decibel = 1 bel
log10(0.25) = -0.60206
Yes like Richter scale for earthquake.
Mr Ironic said:
http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/invsqs.html
——————————————-Yeah but no.
I get twice the distance is 4 times the area… but not a quarter of decibels. Are they like earthquakes?
With the mathamagic provided it gives a starting source of 100 decibels and at 100 mtrs…90 dB
dB is a ratio. For sound the ratio is compared to a base of 10^-12 watts/m^2
http://en.wikipedia.org/wiki/Decibel
log10(0.25) = -0.60206
———————————————-
So is this the 6dB rule?
“Remember it is -6dB per each doubling of distance:
dB SPL/Distance in meters
100/2
94/4
88/8
82/16
76/32
70/64
64/128
58/256
So the difference of 100dB at 2 meters to 58dB at 256 meters, you are 128 times the reference distance but only -42dB from reference.”
Which gives a different result…
Can’t see the different result, please clarify.
For sound the ratio is compared to a base of 10^-12 watts/m^2
——————————————————————————————
Ok…
Does that, not so layman terminology, hold for sound 1,500 mtrs above sea level?
http://en.wikipedia.org/wiki/Sound_pressure
“When measuring the sound created by an object, it is important to measure the distance from the object as well, since the sound pressure decreases with distance from a point source with a 1/r relationship (and not 1/r2, like sound intensity)”
Well the second example suggests 60 to 70 dB at 100 mtrs
70/64
64/128
———————
The other 90…
>100 mtrs
wtf is a mtr?
morrie said:
>100 mtrswtf is a mtr?
Mount Rushmore?
motors. unit of sound intensity. usually compared to a hotted up V8 with a Hotdog muffler.
Boris said:
motors. unit of sound intensity. usually compared to a hotted up V8 with a Hotdog muffler.
does the amp go up to 11?
Boris said:
does the amp go up to 11?
Nigel Tufnel: Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do?
Marty DiBergi: Put it up to eleven.
Nigel Tufnel: Eleven. Exactly. One louder.
by That’s So Taguchi December 19, 2010