day 2 Flashcards

1
Q

similar to the ordinary sounds we hear except that its frequency is higher than the range of human hearing

A

ultrasound

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2
Q

traveling variation in one or more quantities, such as pressure

A

wave

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3
Q

concentration of matter (mass per unit volume).

A

density

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4
Q

acoustic variables

A

period
wavelenght
amplitude
frequency
velocity

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5
Q

Regions of low pressure and density are called

A

rarefactions

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6
Q

regions of high pressure and density are called

A

compression

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7
Q

Sound is a mechanical compressional wave in which back-andforth particle motion is parallel to the direction of wave. Such a wave is called

A

longitudinal wave

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8
Q

The up-and-down motion of a water surface is perpendicular
to the direction of wave travel. This type of wave is called

A

transverse wave

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9
Q

time that it takes for one cycle to
occur

A

period

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10
Q

length of space that one cycle takes up. It is the length of a cycle from “front” to “back.”

A

wavelength

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11
Q

measurement of how often something happens

A

frequency

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12
Q

one complete variation in pressure or other acoustic variable

A

cycle

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13
Q

number of times it is
repeated in 1 second is
called

A

frequency

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14
Q

number of cycles in a wave that occur in 1 second.

A

frequency

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15
Q

sound of a frequency too low for human hearing. less than 20 Hz

A

infrasound

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16
Q

sound of a frequency too high for human hearing. 20000 Hz higher

A

ultrasound

17
Q

It is determined by the medium, primarily its stiffness

A

propagation speed

18
Q

resistance of a material to compression

19
Q

The average propagation speed of sound in tissues

A

1.54 mm/μs

20
Q

Propagation in which speed depends on pressure and the shape of the wave changes

A

nonlinear propagation

21
Q

even and odd
multiples of fundamental
frequency

22
Q

Any other wave shape contains additional frequencies that are even and odd multiples of the original frequency. The original frequency is called the

A

fundamental frequency

23
Q

even and odd multiples of fundamental frequency

24
Q

The first working version of
marine SONAR (Sound Navigation
and Ranging) system was used
during the First World War to detect
enemy submarine

25
early scanning technique required the patient to immersed in a bath of water in order to provide good transmission of sound wave into the body
early 1950's
26
first contact compound B-Scanner (olive oil as lubricant) was developed
late 1950s
27
gray scale imaging was introduced, enabling the display of a wide range of echo amplitudes
1970s
28
real-time scanning systems were introduced. Dynamic Sonograhic Information was available for the first time
Mid 1970s
29
Doppler Technique is used
1980s