7 parameters - Chapter 3

definition: period

time from start of one cycle to start of another cycle

units: period

time

• microseconds

• seconds

• hours

• days

typical values: period

0.06 to 0.5 microseconds

determined by: period

sound source only

adjustable: period

no

definition: frequency

number of cycles that occur in a second

units: frequency

units per second

• 1 cycle/second = 1 Hertz (Hz)

typical values: frequency

2 MHz to 15 MHz

determined by: frequency

sound source only

adjustable: frequency

no

definition: amplitude

difference between maximum value and average value of acoustic variable

units: amplitude

• pressure, Pa

• density, g/cm³

• cm, in, any distance

• decibels, dB

typical values: amplitude

1 million Pa to 3 million Pa

• 1 MPa to 3 MPa

determined by: amplitude

sound source only

adjustable: amplitude

yes

definition: power

rate at which work is performed

unit: power

watts

typical values: power

0.004 to 0.090 watts

• 4 to 90 milliwatts

determined by: power

sound source only

adjustable: power

yes

definition: wavelength

distance or length of one complete cycl

units: wavelength

units of length

• mm

• meters

typical values: wavelength

0.1 to 0.8 mm

determined by: wavelength

both source and medium

adjustable: wavelength

no

definition: speed

rate at which a sound travels through a medium

units: speed

meters/second

typical values: speed

500 to 4000 m/s depending on the tissue

determined by: speed

only by medium

adjustable: speed

no

relationship with: period

• frequency: reciprocal, inverse

• amplitude: directly

relationship with: frequency

• period: reciprocal, inversely

• wavelength: inversely

relationship with: wavelength

• frequency: inversely

relationship with: speed

• stiffness: directly

• density: inversely

relationship with: amplitude

• power: directly

• intensity: directly

• period: directly

relationship with: power

• amplitude: directly

• intensity: directly

relationship with: intensity

• amplitude: directly

• power: directly

formula: period

1/frequency

formula: frequency

1/period

formula: wavelength

speed/frequency

formula: speed

distance/time

formula: amplitude

total height/2

formula: power

work or energy/time

formula: intensity

power/area

definition: intensity

concentration of energy in sound beams

units: intensity

w/cm²

• watts per square cm

typical values: intensity

0.01 to 300 w/cm²

determined by: intensity

sound source only

determined by: intensity

yes