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 2^1/1200

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