2 Sound Flashcards
What are biologic effects of sound?
The effects of the sound wave on biological tissue.
What are acoustic propagation properties?
The effects of the MEDIUM upon the sound wave.
What is sound?
A type of wave that carries energy, not matter, from place to place.
A series of COMPRESSIONS and RAREFACTIONS.
What type of wave makes up sound?
Mechanical and longitudinal wave
What is an acoustic variable?
They help identify which waves are sound waves.
Pressure, density and distance.
What are the units for the 3 acoustic variables (pressure, density and distance)?
Pascals (Pa), kg/cm^3, cm/ft/miles
What is the difference between transverse and longitudinal waves?
The difference is the direction in which particles move.
Transverse waves have particles that move in a perpendicular direction whereas longitudinal waves have particles that move in the same direction as the wave.
What are acoustic parameters?
They describe the feature of a particular sound wave.
Period, frequency, amplitude, power, intensity, wavelength, and speed.
What is a period?
The time required to complete a single cycle.
Typical values: 0.06-0.5 microsec
Determined by sound source
NOT changed by sonographer
What is frequency?
Number of certain events that occur in a particular time duration.
(Number of cycles of an acoustic variable that occur in 1sec)
1/second= Hertz, Hz
Typical values: 2MHz-15MHz
Determined by sound source
NOT changed by sonographer
What is the range of audible sound?
20 Hz-20,000 Hz
How are frequency and period related?
They are reciprocals or an inverse relationship.
Remember to use complementary units!
What are the 3 bigness parameters?
Amplitude, Power, Intensity
These describe a sound beam’s strength.
What is amplitude?
The difference between the average value and the max value of an acoustic variable, the variation of an acoustic variable.
Measured in decibels.
Determined by sound source.
YES can be changed by sonographer.
What is power?
The rate that work is performed, or rate of energy transfer.
Watts
Determined by sound source.
YES can be changed by sonographer.