INTERESTING FACT OF THE DAY

Originally Posted by grh1904

(foot patrol wearing boots, stab vest, helmet and utility belt)

is it like batman's utility belt? becasue then you could use your bat boomerang of death on him

Originally Posted by kd sweety

is it like batman's utility belt? becasue then you could use your bat boomerang of death on him

No, but I like your style.


Note to self - First thing in work tomorrow, see admin for requisition forms for "Boomerang of Death"

If your ears ring after hearing continuous loud noises you will never hear the frequencies of that ring ever again

Originally Posted by cb5_keith

If your ears ring after hearing continuous loud noises you will never hear the frequencies of that ring ever again

How long, and at what volume, does the average person have to be exposed to said frequency before he/she cannot hear it?

Matt

Originally Posted by alpinestarhero

How long, and at what volume, does the average person have to be exposed to said frequency before he/she cannot hear it?

Matt

Generally, over 90-100dB for longer than 30 minutes to an hour will cause lasting damage. 125dB+ will cause pain. 180dB will destruct hearing tissue.
When you begin to look at frequencies it can get very complicated as day to day sounds consist of many frequencies from 20Hz to 20KHz (the hearing range).
Hearing, or percieved loudness, can be simulated in a logarithmic scale using an A-weighting curve...

This means our ears will be more sensitive to frequencies between 2kHz and maybe 8kHz, than to say 20 to 800Hz.
Therefore, damage will most likely occur at the frequencies where the curve is peaking, because lower and much higher frequencies are perceived to be quieter...

Originally Posted by cb5_keith

Generally, over 90-100dB for longer than 30 minutes to an hour will cause lasting damage. 125dB+ will cause pain. 180dB will destruct hearing tissue.

Which dB scale are you using there? I have seen that the graph is in dB(V).

Another interesting factoid is that my bike horns are approx 142dB(A). They do cause a little pain if you hold your finger on the button, but you get used to it, and they do seem to be quieter than they were. I put that down to me getting used to them though.

Those figures would be dB SPL...

When referring to decibels on an a-weighting scale the denotation is dB(A). The A refers to the a-weighting. For a b-weighting scale it would be dB(B). However, if you refer to an acoustic sound/measurement then dB SPL should be used. 0 dB SPL is referenced to 20 micropascals. But dB SPL can't be converted to dB(A), or the other way around!

If you want a more sophisticated method to determine the pressure of sounds in terms of frequencies then the fletcher-munson curves suffice. Each curve presents the pressure level (dB SPL) over hearing range in terms of frequencies (20Hz to 20KHz) for an equal-loudness signal (phon). 1 phon is equal to 1 dB SPL at 1KHz.

However, these curves are created from pure sine waves at each frequency so can't really be related to real world sounds....although your horn Baph may be rather close to a pure tone...

Is it obvious I have nothing better to do with my time???

6% of Americans believe Elvis Presley is still alive.
An ostriches eye is bigger than it's brain.
Elephants are the only animals that can't jump.

Ummm... That seems to be all I can think of at the moment =/

However, with the National hunt [sort of] on this week. Here's a bit of information that might amuse you:
Letherby & Christopher, the racecourse caterers, will serve some:
20,000 bottles of champagne,
30,000 bottles of wine,
240,000 bottles of beer and lager,
220,000 pints of Guinness,
and 10,000 gallons of tea and coffee!!

Originally Posted by Mark_h

Apparently a Duck's quack does not echo.

There's a fairly entertaing show on the Discovery channel here in the states. They try to prove or disprove myths and things just like this...

http://en.wikipedia.org/wiki/MythBus..._Quack_Echo.3F

It echos, but the quack itself and the echo have such similar acoustic properties that it is very difficult for a person hear where the quack stops and the echo starts!