7 parameters Flashcards
Period
It is the time elapsed from the beginning of one cycle to the beginning of the next; a period is inversely related to the frequency and directly related to wavelength.
Wavelength
It is the distance from the beginning of one cycle to the beginning of the next; wavelength is inversely related to the frequency and directly related to the period.
Frequency
It is the number of cycles that can occur per unit of time, expressed in a unit of Hertz (Hertz can also be expressed as per second); frequency is inversely related to period and wavelength.
Propagation speed
It is the rate of speed at which acoustic energy travels through a medium and is dependent on the medium; sound travels quickest in solids, slower in liquids, and slowest in gasses.
High stiffness, low density mediums demonstrate the highest propagation speed.
The average speed of sound in soft tissue is 1,540 m/s.
Amplitude
It is the magnitude of a wave, expressed as a difference between the maximum and average or minimum and average values of a wavefront.
Peak-to-peak amplitude is the difference between the maximum and minimum values of a wavefront.
Amplitude is expressed as a unit of pressure, decibels, density, or particle motion.
Power
It is the rate of energy transfer and describes the strength of a wave; the power of a wave decreases as acoustic energy propagates through a medium due to the process of attenuation. Power is expressed in a unit of Watts.
Intensity
It is the concentration of energy in the acoustic beam and describes the distribution of a wave’s power in a specified area (intensity = power/cross-sectional area); intensity is directly related to power and is proportional to a wave’s amplitude squared. Intensity is expressed in a unit of W/cm2.
