Physical Quantities
GOOD LINK
http://www.isd.mel.nist.gov/projects/omacapi/Software/MeasuresAndUnits/Measure
sandUnitIntroduction.html
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Physical Quantities

Base quantities vs. Derived quantities
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Base or Fundamental quantities


Quantities that must be measured
Base measures from which all others
are derived
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Selected Base Quantities
1.
2.
3.
Distance or Length (l)
Mass (m)
Time (t)
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Systems of Measure
English system: fps system
F: foot
P: pound
S: second
Metric system
cgs system
c: centimeters
g: grams
s: seconds
Metric system
(System International)
mks system
m: meter
k: kilogram
s: second
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What is the mass of speech structures?
Vocal folds ~ 2 grams
combined!!
Lips
~ 25-50 grams each
SPPA 4030 Speech Science
Tongue
~ 150 grams
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What are typical distances moved by
speech structures?
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What is the typical duration of speech
events?
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Scalar vs. Vector quantities
Scalar quantities

Has only a magnitude
Vector quantities


Includes more than one piece of information
i.e. Magnitude AND direction
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Area and Volume
Area
 2-dimensional
 distance2
l
Volume
 3-dimensional
 distance3
l
l
l
l
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Displacement


Jaw vertical position

Displacement is a change in position
Is a vector quantity
Has a magnitude (basic quantity of length)
Has a direction
KINEMATIC FEATURES OF VERTICAL JAW MOTION
JAW POSITION

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Time
Velocity (v)

Rate at which a quantity changes it’s value
v = x/t

May be expressed as


where
v = velocity
x = distance
t = time

Velocity units





average velocity
instantaneous velocity
m/sec (SI)
cm/sec
miles/hour
Velocity vs. speed
Volume velocity or flow
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Velocity (v)
JAW VELOCITY
JAW POSITION
KINEMATIC FEATURES OF VERTICAL JAW MOTION
40
0
LERATION
-40
1000
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Acceleration (a)

Rate of change in velocity


‘speeding’ up or positive acceleration
‘slowing’ down or negative acceleration
a = v/t
May be expressed as

where
a = acceleration
v = velocity
t = time

average acceleration
instantaneous acceleration
Acceleration units

SPPA 4030 Speech Science
m/sec2 (SI)
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JAW VELOCITY
JAW POSITION
KINEMATIC FEATURES OF VERTICAL JAW MOTION
40
0
JAW ACCELERATION
-40
1000
0
-1000
TIME
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Force (F)

Is a push or a pull on an object
F = M*a
Force ↑ (or ↓)

where
F = force
M = mass
a = acceleration

↑ (or ↓) mass
↑ (or ↓) acceleration
Force units


SPPA 4030 Speech Science
Newton (SI)
dyne
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Pressure (E or P)

Force distributed over an area
E = F/A
where
E = pressure
F = force
A = area (x2)
Pressure units


SPPA 4030 Speech Science
Pascal (SI)
dyne/cm2
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Ways to increase Pressure
= area
= force
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Work (W)
Force applied over a given distance
W = F*x
Work ↑ (or ↓)


where
W = work
F = force
x = distance
↑ (or ↓) force
↑ (or ↓) distance
Work units



SPPA 4030 Speech Science
Joule (SI)
Erg
Footpound
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Power (P)
Power = rate at which work is done
Power (P)
P = W/t
where
P = Power
W = work
t = time
Power units


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Watt (SI)
horsepower
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Intensity (I)


Area over which power is focused
Intensity is to power what pressure is to force
I = P/A
where
I = Intensity
P = Power
A = area
Intensity units

SPPA 4030 Speech Science
watt/cm2
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Resistance

acoustic or aerodynamic resistance = pressure/flow

In electrical world
Ohm’s Law
R=E/I
where
R= resistance
E=voltage
I=electric current
Note: voltage is an electric analog to pressure
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