Name: Jenna T.
What is a decibel and what is the difference between dB
and dBA? Also can you give comparison's in sound to say 5 dBA and
10dBA? Also what is an Ohms reader?
A decibel is a measure of sound loudness -- the square of the
compressional pressure. IT IS A LOGARITHMIC SCALE. There are two weighting
scales for measuring the loudness. The "C" scale has a flat sensitivity from
32 to 10,000 hertz. Above 10,000 hertz the sensitivity falls off rather
rapidly due to the physical limitations of the microphones above that
frequency. The "C" weighting is assigned a response of 0 dB across its range
of sensitivity (This is arbitrary). The "A" scale is weighted to approximate
the typical sensitivity of the human ear (Obviously, this is an average
population). Between 1000 and 10,000 hertz the sensitivity of the two scales
is essentially the same. At 500 hertz the "A" scale is about -10 dB; at 100
hertz the "A"scale is about -25 dB; at 50 hertz the "A" scale is about -40
dB, and at 20 hertz the "A" scale is about -50dB.
One dB is approximately the faintest sound audible to the human ear;
background music is about 50 dB; heavy rock music is about 110dB; pain
threshold is about 125 dB.
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Update: June 2012