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The above is an audio demonstration of decibels. A sound card is required to play the 250Hz tones.
What is a decibel? You can see from the
Acoustics FAQ that the decibel is a logarithmic unit which is used in a number of scientific disciplines. The program is intended to show the relative change in audible
sound with the change in decibels.
The sounds should be heard as continuous tones. However, there may be a slight
'click' as the sound buttons are changed which could be misleading. Switch buttons
back and forth a few times to get an idea of the steady levels. Most people
will find the change of 3dB just perceptible.
A Java capable browser is required. The software makes use of five .au files in
addition to the .class file and this .asp page. The program may need a few
moments to start.
* Press the “Ref” button to hear the reference
tone. When all of the earwax has poured out of your ears, press the “stop”
button.
* Press the “-3 dB” button to hear a tone that is 3 dB lower in intensity than
the reference tone. Compare the loudness of this tone to the reference value.
Press “stop”.
* Continue with the “-6 dB”, “-10 dB”, and “-20 dB” buttons. Compare the
loudness of these tones to each other and to the reference tone.
Again, most people will find a change of 3dB just
perceptible. Every time you double (or halve) the power level, you add (or
subtract) 3 dB to the power level. This corresponds to a 50% gain or reduction.
10 dB gain/loss corresponds to a ten-fold increase/decrease in signal level. A
20 dB gain/loss corresponds to a hundred-fold increase/decrease in signal level.
In other words, a device that has 20 dB loss through it will lose 99.9% of its
signal by the time it gets to the other side. Thus, big variations in signal
levels are easily handled with simple digits.
From more information on acoustics read
Occupational noise exposure by the U.S. Department of Labor,
Occupational Safety & Health Administration. The above link will be educational
for individuals that enjoy listening to loud music or music with ear phones.
You may be surprised to learn what is considered a safe sound level or decibel.
Note the "daily noise exposure limits".
Contact an All Tech Insulation engineer today
(432-897-1533)
for a deeper discussion about your specific acoustic requirements.
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