Chapter 3 in Edelman
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
|
|
||||
|---|---|---|---|---|---|
| The 7 parameters that characterize a sound wave | Period, frequency, amplitude, power, intensity, wavelength, and speed
🗑
|
||||
| The parameters of sound wave are determined by 2 things | The source of the sound wave and the medium it is traveling through
🗑
|
||||
| Definition of period | The time it takes a wave to vibrate a single cycle, or the time from the start of one cycle to the the start of the next cycle. Reported in units of time
🗑
|
||||
| Typical ultrasound period | 0.06 to 0.5 microseconds
🗑
|
||||
| Characteristics of a period | Period is determined by the sound source only, not by the medium and is NOT adjustable
🗑
|
||||
| Definition of frequency | The number of particular events that occur in a specific duration of time. Reported in units per second
🗑
|
||||
| Typical ultrasound frequency | 2 Mhz to 15 Mhz or 2 million to 15 million per second
🗑
|
||||
| Characteristics of frequency | Frequency of a sound wave is determined by the sound source only, not by the medium and is NOT adjustable
🗑
|
||||
| Audible sound frequency | 20 Hz to 20,000 Hz
🗑
|
||||
| Infrasonic frequency or infrasound | Lower than 20 Hz
🗑
|
||||
| Ultrasonic frequency or ultrasound | Higher than 20,000 Hz (20 kHz)
🗑
|
||||
| How are period and frequency related? | Inversely; as frequency increases, period decreases; as frequency decreases, period increases. They are also reciprocal
🗑
|
||||
| 3 parameters describe the size, magnitude or strength of a sound wave | Amplitude, power & intensity. These are the only parameters of the 7 that the sonographer can adjust.
🗑
|
||||
| Definition of amplitude | Amplitude is the "bigness" of a wave. It is the difference between the maximum (or minimum) value and the average or undisturbed value of an acoustic variable. Reported in pascals
🗑
|
||||
| Typical ultrasound pressure amplitude | 1 million pascals to 3 million pascals or 1 Mpa to 3 Mpa
🗑
|
||||
| Characteristics of pressure amplitude | Amplitude is determined initially by only the sound source, however, amplitude decreases as sound propagates through the body. Amplitude is adjustable
🗑
|
||||
| Definition of power | Power is the rate of energy transfer or the rate at which work is performed. Like amplitude, it describes the "bigness" of a wave. Reported in watts
🗑
|
||||
| Typical ultrasound power | 0.004 to 0.090 watts (4 to 90 milliwatts)
🗑
|
||||
| Characteristics of power | Initial power is determined by the sound source, but power decreases as sound propagates through the body. Power is adjustable
🗑
|
||||
| How are power and amplitude related? | Power is proportional to amplitude squared
🗑
|
||||
| Definition of intensity | Intensity is the concentration of energy in a sound beam. Intensity describes the "bigness" of a wave. Intensity relates to how the power in a wave spreads or is distributed in space. Reported in watts per cm squared (W/cm squared)
🗑
|
||||
| Typical ultrasound intensity | 0.01 to 300 W/cm squared
🗑
|
||||
| Characteristics of intensity | Initial intensity is determined by only the sound source, but intensity changes as sound propagates through the body. Intensity is adjustable by
🗑
|
||||
| How are intensity and power related? | Intensity (W/cm squared) = power (W)/area (cm squared)
🗑
|
||||
| How are power, amplitude and intensity related? | They are directly related. Therefore when one increases, the others increase. Intensity is proportional to power. Intensity is proportional to amplitude squared. Power is proportional to amplitude squared.
🗑
|
||||
| Definition of wavelength | Wavelength is the distance or length of one complete cycle. Reported in mm
🗑
|
||||
| Typical ultrasound wavelength | 0.1 to 0.8 mm
🗑
|
||||
| Characteristics of wavelength | Wavelength is the only parameter determined by BOTH the source and the medium and is NOT adjustable
🗑
|
||||
| The wavelength in soft tissue | In soft tissue, sound with a frequency of 1MHz has a wavelength of 1.54 mm
🗑
|
||||
| How are frequency and wavelength related? | Wavelength (mm) = 1.54 mm/microsecond/frequency (MHz)
🗑
|
||||
| Propagation speed | The rate at which a sound wave travels through a medium. Measured in m/s or mm/microsec
🗑
|
||||
| Characteristics of propagation speed | Speed is the only parameter determined by the medium ONLY and is NOT adjustable by the sonographer. The Stiffness and density of an object affect the speed of sound.
🗑
|
||||
| Speed of sound in soft tissue | 1540 m/s or 1.54 mm/microsec or 1.54 km/s
🗑
|
||||
| Stiffness | The ability of an object to resist compression. Speed and stiffness are directly related. Also known as bulk modulus. Elasticity and compressibility are the opposite of stiffness.
🗑
|
||||
| Density | The relative weight of a material. Speed and density are inversely related.
🗑
|
Review the information in the table. When you are ready to quiz yourself you can hide individual columns or the entire table. Then you can click on the empty cells to reveal the answer. Try to recall what will be displayed before clicking the empty cell.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Created by:
gillybruursema
Popular Sonography sets