Sound

Question 1

Pressure

Answer 1

Force (measured in Pascals)

Question 2

Density

Answer 2

Concentration of mass (measured in kg/cm^3)

Question 3

Distance

Answer 3

Particle Motion (measured in cm, feet, miles)

Question 4

Transverse wave

Answer 4

particles move in perpendicular direction

Question 5

Longitudinal wave

Answer 5

Particles move in the same direction (sound waves are longitudinal)

Question 6

Compressions

Answer 6

higher pressure

Question 7

Rarefactions

Answer 7

lower pressure

Question 8

Name the 7 acoustic parameters

Answer 8

period
frequency
power
amplitude
intensity
speed
wavelength

Question 9

What are the 3 acoustic variables that constitutes a sound wave?

Answer 9

1. amplitude
2. power
3. intensity

Question 10

Period

Define:
Units:
Determined by:
Changed by sonographer?

Answer 10

Define: Time required to complete one cycle (time from the start of a cycle to the start of the next cycle)

Units: seconds *all units of time

Determined by: sound source

Changed by sonographer? no

Question 11

Frequency

Define:
Units:
Determined by:
Changed by sonographer?

Answer 11

Define: # of cycles of an acoustic variable that occur in one second

Units: Hertz = per second

Determined by: sound source

Changed by sonographer? no

Question 12

Ultrasound

in Hz, MHz, KHz

Answer 12

Anything above
20,000 Hz
20 KHz

Question 13

Audible Sound range

Answer 13

20Hz - 20,000 Hz

Question 14

Amplitude

Define:
Units:
Determined by:
Changed by sonographer?

Answer 14

Define: strength of a sound beam

Units: (pressure, density, particle motion) can be expressed in dB

Determined by: sound source

Changed by sonographer? yes

Question 15

Amplitude is equal to

Answer 15

half of the peak to peak amplitude

Question 16

Amplitude _________ as sound propagates through the body

Answer 16

decreases

Question 17

Power

Define:
Units:
Determined by:
Changed by sonographer?

Answer 17

Define: rate that work is performed

Units: Watts

Determined by: sound source

Changed by sonographer? yes

Question 18

Power _________ as sound propagates through the body

Answer 18

decreases

Question 19

If the amplitude is tripled, the power is __________ by a factor of _____

Answer 19

increased; 9

Question 20

If amplitude is halved, the power is ____________ by a factor of ______

Answer 20

decreased; 4 (quartered)

Question 21

Intensity

Define:
Units:
Determined by:
Changed by sonographer?

Answer 21

Define: concentration of energy in a sound beam

Units: watts/square cm

Determined by: sound source

Changed by sonographer? yes

Question 22

Intensity depends upon ___________ & _______

Answer 22

power and beam area