丁香园AV

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

* 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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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