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What units are used to measure sound?
The sciences involve quantitatively measuring properties of the natural world. When a scientist is making measurements, they must first identify the specific properties they will measure, how those measurements will be made, and what units they will use. For example, if a scientist is measuring the property of water depth, it would not be enough to say the water is 250 deep. That could mean 250 feet, 250 meters, or 250 fathoms. The scientist must provide the units for that value.
It is also important to understand how to convert units from one unit to another. Most Americans know that 12 inches is equal to 1 foot, but it may not be known that 1 nautical mile is equal to 1.85 kilometers. It is well known that 1 kilometer is equal to 1,000 meters, but not so well known that 1 micrometer is equal to 10-6 meters.
There are fixed units such as meters and relative units such as decibels (dB). Relative units are related to specific conditions. For example, decibels in water have a different relative value than decibels in air. Scientists have agreed to use 1 microPascal (μPa) as the reference pressure for underwater sound. In air, however, scientists have agreed to use a higher reference pressure of 20 microPascals.
Sound intensity given in dB in water is therefore not the same as sound intensity given in dB in air.
Sound Intensity Formula:
Sound intensity is the sound energy per unit area per unit time perpendicular to direction of sound waves. It is represented as I.
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The sound intensity is given as,
[pic]
Where, P is the sound power,
A is the area
To measure Sound intensity level we compare the given sound intensity with the standard intensity.
Sound Intensity Level Formula is given by,
[pic]
Where I = sound intensity and
Io = reference intensity
It is expressed in decibels (dB).
Sound Intensity Formula is used to determine the intensity of sound waves. The S.I unit of sound intensity is Watt per meter square (W/m2).
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