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Appendix B
UNITS OF MEASUREMENT


Name

Abbreviation

Unit of

Equivalent or definition

atmosphere

atm

pressure

1 atm is normal atmospheric pressure

1 atm = 1.013 x 105 N/m2 = 1.013 bar = 14.7 lbs/in2

bar

-

pressure

1 bar = 106 dynes/cm2 = 106 µbar = 0.9869 atm

bel

-

intensity level

see decibel below

cent

-

frequency ratio

(interval)

1 cent corresponds to a frequency ratio of 21/1200

100 cents = 1 semitone

1200 cents = 1 octave

cycles per second

cps

frequency

1 cps = 1 Hz (see hertz below)

decibel

dB

intensity level

1 dB = 0.1 bel = log I1/I2 where I1 = 10.I2

dyne

dyn

force

1 dyn = 10-5 N = 1 gm cm/sec2

erg

-

energy

1 erg = 10-7 J = 1 gm cm2/sec2

gigahertz

gHz

frequency

1 gHz = 109 Hz = 103 mHz = 106 kHz

hertz

Hz

frequency

1 Hz = 1 cycle/sec = 1 cps

1000 Hz = 1 kHz = 1 kc

joule

J

energy

1 J = 107 erg = 1 kg m2/sec2

kilocycle

kc

* frequency

1000 cycles

1 kilocycle/sec = 1 kc = 1000 cps = 1 kHz

kilohertz

kHz

frequency

1 kHz = 1000 Hz

megacycle

mc

* frequency

106 cycles

1 megacycle/sec = 1 mc = 106 cps = 1 mHz

megahertz

mHz

frequency

1 mHz = 106 Hz = 103 kHz

mel

-

pitch

1000 Hz at 40 dB is defined as 1000 mels

microbar

µbar

pressure

1 microbar = 10-6 bar = 1 dyne/cm2

Threshold of Hearing is 2 x 10-4 µbar

microsecond

µsec

time

1 µsec = .001 ms = 10-6 sec

mil

-

distance (thickness)

1 mil = .001 inch

millisecond

ms

time

1 ms = .001 sec

Newton

N

force

1 N = 105 dyn = 1 kg m/sec2

noy

-

noise

See PERCEIVED NOISE LEVEL

Pascal

Pa

pressure

1 Pa = 1 N/m2 = 106 µPa

phon

-

loudness

See: PHON, EQUAL LOUDNESS CONTOURS

sabin

-

absorption

1 sabin is equivalent to 1 squre foot of a surface absorbing all incident energy

sone

-

loudness

1 sone = 40 phons

watt

w

energy flow or power

1 watt = 1 joule/sec

* The terms kilocycle and megacycle, just as the basic term cycle, are often used loosely meaning frequency units. Proper frequency specification would be cycles/sec, kilocycles/sec, megacycles/sec. Partly due to this ambiguity, ther terms hertz, kilohertz and megahertz have been introduced as standard units of frequency.


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