Describing Sound Waves - Period & Frequency Flashcards
Describes the features of a sound wave
Parameters
The ______ of a sound wave is the ultrasound system and transducer.
Source
The quantity, or level, of some of the parameters are established by the…
Ultrasound system
Other parameters are determined by the tissue through which the sound is traveling. This tissue is called the…
Medium
The time it takes a wave to vibrate a single cycle, or the time from the start of one cycle to the start of the next cycle.
Period
Period is reported in ____of time, such as microseconds, seconds, hours, or days.
Units
The typical value of a period in diagnostic ultrasound is…
0.06 to 0.5 μs
Period is determined by the _______ only, not by the medium.
Sound source
True or False? The period can be changed while using a basic ultrasound system with a particular transducer.
False
The number of particular events that occur in a specific duration of time…
Frequency
In diagnostic ultrasound, the frequency of a wave is described as the number of ______ that occurs in one second.
Cycles
Frequency is reported in units of …
Per second, 1/second, hertz (Hz) (another way to say “per second”
In clinical imaging, frequency ranges from approximately…
2 MHz to 15 MHz (or 2 million to 15 million per second)
Frequency of a sound wave is determined by the _______ only.
Sound source
True or False? The sonographer cannot change the frequency while using a basic ultrasound system and transducer.
True
Infrasound (infrasonic) frequency
Less than 20 Hz
Audible sound frequency range
Between 20 Hz and 20 kHz
Ultrasound (ultrasonic) frequency range
Greater than 20 kHz
Frequency in ultrasound is important because it affects _______ and image ______.
Penetration, quality
Period and frequency are _______ related to each other.
Inversely
As frequency increase, period ______.
As frequency decreases, period ______.
If one of these parameters remains constant, then the other remains _______.
Decreases, increases, unchanged
Period and frequency have an even more special relationship called…:
Reciprocal
When two reciprocal parameters are multiples together, the result is…
1
What is the period of the earth’s rotation around the sun?
1 year
A top is spinning on a table. What is the period of the spinning top?
A. 4 pounds
B. 8 dollars
C. 0.05 seconds
D. 3 cm
C. 0.05 seconds
Which of the following waves is infrasonic?
A. 4 MHz
B. 400 kHz
C. 28 Hz
D. 2 Hz
D. 2 Hz
Indentify the wave that is ultrasonic.
A. 400 mHz
B. 4 MHz
C. 28 Hz
D. 2 Hz
B. 4 MHz
Which of these waves is ultrasonic and most useful in diagnostic sonography?
A. 400 MHz
B. 4 MHz
C. 2 kHz
D. 200,000 Hz
B. 4 MHz
Identify all the waves that are inaudible.
A. 4 MHz
B. 400 kHz
C. 28 Hz
D. 2 Hz
A. 4 MHz
B. 400 kHz
D. 2 Hz
Which of the following waves has the longest period?
A. 2 MHz
B. 4,000 Hz
C. 6 Hz
D. 1 kHz
C. 6 Hz
Of the four waves whose periods are listed below, which has the highest frequency?
A. 8 s
B. 80 μs
C. 8 Ms
D. 800 ks
B. 80 μs
Of the four waves whose frequencies are listed below, which has the shortest period?
A. 12 kHz
B. 6,000 Hz
C. 205 Hz
D. 1 kHz
A. 12 kHz
Of the four waves whose periods are listed below, which had the lowest frequency?
A. 8 s
B. 80 μs
C. 8 Ms
D. 800 ks
C. 8 Ms
The three “bigness” parameters…
Amplitude, power, intensity
The bigness of the wave, or difference between the maximum value and the average or undisturbed value of an acoustic variable.
Amplitude
Amplitude can have units of any of the acoustic variables, which are…
Pressure (pascals), density (g/cm^3), distance (particle motion)(cm/inches).
Can also be expressed in decibels (dB)
In clinical imaging, pressure amplitude ranges from…
1 million pascals (1 MPa) to 3 million pascals (3 MPa)
Initially, amplitude is determined only by the ______. However, amplitude ______ as sound propagates through the body.
sound source, decreases
The rate at which amplitude decreases as sound propagates depends on the characteristics of both the ______ and the ______.
Sound wave, medium
True or false? A control on a basic ultrasound system allows the sonographer to alter initial amplitude of a wave.
True
Measured from the middle, or undisturbed, value to the maximum value.
Amplitude
Difference between maximum and minimum values of an acoustic variable. Twice the value of amplitude.
Peak-to-peak amplitude
The rate of energy transfer or the rate at which work is performed.
Power
Power has units of…
Watts
In clinical imaging, typical powers range from…
0.004 to 0.90 watts (4 to 90 milliwatts).
When power increases, amplitude…
Increases
Mathematically, power is proportional to the wave’s amplitude _______.
Squared, a number multiplied by itself
Just like amplitude, initial power is determined only by the _________, the ultrasound system.
Sound source
True or False? There is no control on ultrasound systems that allows the sonographer to alter the initial power of the wave.
False
When you think of power, think of a…
Light bulb
Concentration of energy in a sound beam.
Intensity
To calculate intensity, divide the beam’s _________ by the beam’s __________ area.
Power, cross-sectional
Intensity relates to how the power in a wave _______ or is ________ in the space.
Spreads, distributed
Intensity depends on both the power in the _____ and the _____ over which the power is applied.
Beam, area
