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Agenda - 06-27-1983
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Agenda - 06-27-1983
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4/24/2017 8:06:06 AM
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BOCC
Date
6/27/1983
Meeting Type
Regular Meeting
Document Type
Agenda
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Minutes - 19830627
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\Board of County Commissioners\Minutes - Approved\1980's\1983
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411 <br /> Sound Pressure Level <br /> Our ears are sensitive to a wide range of sound pressures . The <br /> loudest sounds that we hear without pain have about one Million times <br /> more energy than the quietest sounds we hear. Also , ourj, ears are not <br /> equally sensitive to all sound pressures -- it takes more energy to <br /> 3 <br /> produce a noticeable change in a loud sound than it doesl, to produce a <br /> noticeable change in a quiet sound . We can reduce the range of sound <br /> pressures to which we are sensitive to a more manageable range , and we <br /> can account for the nonlinear sensitivity of our ears by introducing the <br /> concept of sound pressure level . In acoustics , the term "level" is used <br /> to refer to a logarithmic value of the ratio of a sound pressure <br /> quantity relative to a reference quantity . <br /> Sound pressure level is a measure of sound pressure relative to a <br /> reference pressure of 20 micropascals , 0 .0002 microbarp , or 2x105 <br /> newtons per square meter . All of these values are equivalent and are in <br /> common use . In your work with airport noise , you are goingl to hear a lot 41M <br /> about sound pressure level , because it is the sound pressure level to <br /> which people respond , pro or con , in their living and working <br /> environments . <br /> The language of acoustics is full of abbreviations , and there are <br /> two for sound pressure level : "SPL" and "L " "SPL" is more Widely used . <br /> ; P 1 <br /> Decibels <br /> Sound pressure levels are measured in decibels (ab reviation: <br /> "dB") , just as distance is measured in inches and temperature is <br /> measured in degrees . Decibels are used to express the ratio of two <br /> quantities in logarithmic terms . The table below shows a comparison of <br /> various sound pressures ( measured in microbars) and their; associated <br /> sound pressure levels ( expressed in decibels) . <br /> 411 <br /> 5 <br /> 'FLIPP t "..1 <br />
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