chapter 1, 2, & 3 of ultrasound physics

edelman, chat gpt, and YouTube

ultrasound refers to sound waves with frequences greater than _

20,000 Hz, beyond the range of human hearing.

audible sound typycally ranges between _ and _ Hertz

20 - 20,000

Medical ultrasound typically uses frequencies between

2 MHz and 15,000 MHz

infrasound is lower than

20 Hz

differences between directly related (directly proportional), related (proportional), and inversely related (inversely proportional)

Directly related variables increase together

related variables are associated or affiliated, but the relationship isn’t specified

Inversely related variables move in opposite directions.

What is a reciprocal relationship

Two numbers whose product is equal to one. A special form of an inverse relationship, where one variable increases while the other decreases.

for a numerical answer to a question to be comprehensive, it requires a

unit of measurement.

increase by the factor means to _ by that number, and decrease by the factor means to _ by that number

multiply, divide

a number followed b y a percent is

unitless and represents a ratio of the number to 100.

metric system power of ten chart

sound is a _, _ wave that travels through a medium by particle vibration

mechanical, longitudinal

sound requires a _ to propagate

medium, it cannot travel through a vacuum

The difference between longitudinal and mechanical properties in sound waves

Longitudinal waves refer to sound waves where particle vibration occurs in the same direction as wave propagation, while mechanical properties involve the physical characteristics of the medium through which the sound travels.

sound travels as a series of _ and _

compressions and rarefactions

what are acoustic variables

Acoustic variables are physical quantities that describe the state of a sound wave.

What are the 3 acoustic variables

Pressure (Pascals, Pa), density (kg/m³), and distance (particle motion, mm, cm)

what are acoustic parameters

Acoustic parameters are characteristics that define the properties of sound waves, including frequency, wavelength, amplitude, and speed.

Difference between acoustic variables and acoustic parameters

Acoustic variables describe the state of a sound wave, while acoustic parameters define the features of those sound waves.

Period

µs

Time for one cycle

Frequency

MHz

Cycles per second

Amplitude

dB

Strength of the wave

Power

Watts

Rate of energy transfer

Intensity

W/cm²

Power per area

Wavelength

mm

Distance of one cycle

Propagation Speed

m/s

Speed through a medium

in ultrasonography, sound pulses created by a transducer travel through biological tissue, or

media

all waves carry _ from one location to another

energy

Many different forms of waves exist, including

heat, sound, magnetic, and light.

sound is a _ wave

mechanical

sound _ travel through a vacuum, it travels through a

cannot, medium

sound travels in a _ line

straight

sound waves are _ waves

longitudinal

acoustic propagation properties

The effects of the medium upon the sound wave, such as speed, frequency, and wavelength. media affects sound

biological effects

The effects of the sound wave upon the biological tissue through which it passes. Sound affects media

Pressure is the concentration of force in an _, units are _

area, pascals

density is the concentration of mass in a _, units are _

volume, kilograms per cubic meter (kg/m³)

Distance is the measure of _, units are _

particle motion, cm, feet, mile

What are the seven acoustic parameters

period, frequency, amplitude, power, intensity, wavelength, and propagation speed.

difference between transverse waves and longitudinal waves

Transverse waves move perpendicular to the direction of energy transfer, while longitudinal waves move parallel. Examples include waves on a string for transverse and sound waves for longitudinal.

what is considered an in-phase wave

An in-phase wave is when two or more waves have the same frequency and their peaks and troughs align, resulting in constructive interference and increased amplitude.

what is considered an out-of-phase wave

An out-of-phase wave occurs when two or more waves have a frequency but their peaks and troughs do not align, resulting in destructive interference and decreased amplitude.

what is interference in sound waves

Interference in sound waves refers to the phenomenon that occurs when two or more sound waves overlap and combine, resulting in either an increase (constructive interference) or decrease (destructive interference) in sound intensity, depending on their phase relationship.

constructive interference vs destructive interference

Constructive interference occurs when waves align in phase, leading to an increase in amplitude, while destructive interference happens when waves are out of phase, causing a reduction in amplitude.

out-of-phase waves of equal amplitude may

cancel each other out

the source of a sound wave is the ultrasound system and

transducer

tissue is also called the

medium

period is the _ it takes a wave to vibrate in a _

time , single cycle

period is deteremined by the _ only, not the

sound source, medium

is period adjustable

no

frequency is the _ of particular events that occur in a specific duration of

number, time

in diagnostic ultrasound, the frequency of a wave is described as the number of _ that occurs in _ second

cycles, one

frequency of a sound wave is determined by the _ only

sound source

is frequency adjustable

no

period and frequency are _ related to each other

inversely

as frequency increases, period

decreases

period and frequency also have a _ relationship

reciprocal

period x frequency =

1

what are the 3 bigness parameters

Amplitude, Power, Intensity

amplitude is the bigness of the wave, it is the difference between the _ value and _value of an acoustic variable

maximum?minimum, average or undisturbed

Amplitude is usually expressed in

decibels

amplitude can have units of

any acoustic variable

amplitude is determined only by the

sound source

is amplitude adjustible

yes

amplitude is measured by the _ value to the _ value

middle (undisturbed), maximum

peak-to-peak amplitude

is the difference between the maximum and minimum values of the waveform.

power is the rate of _ transfer or the rate at which work is performed

energy

power has units of

watts

power is deteremined only by the _, power _ as sound propagates through the body

sound source, decreases

is power adjustable

yes

what is the relationship between amplitude and power

Power is proportional to the square of the amplitude; as amplitude increases, power increases dramatically.

formula between power and amplitude relationship

Power = Amplitude²

intensity is the concentration of _ in a _

energy, sound beam

the units of intensity are

watts per square meter (W/m²)

intensity is determined by the

sound source

is intensity adjustable

yes

intensity formula

power (w)/ area (cm²)

intesity is _ to power

proportional

intensity is proportional to the wave’s amplitude _

squared

squared always follows the word

amplitude

wavelength is the _ or _ of one complete cycle

distance or length

wavelength is deteremined by both

the source and the medium

is wavelegnth adjustable

no

wavelength is the only parameter that is determined by both

the source of the ultrasound and the medium through which it travels.

both _ and _ describe a single cycle in a sound wave

wavelegnth and period

what is the relationship between wavelength and frequency

Wavelength and frequency are inversely related; as the frequency of a sound wave increases, its wavelength decreases, and vice versa. This relationship is described by the equation: speed = frequency x wavelength.

shorter wavelengths are created by _ frequency sounds

high

propagation speed is the rate at which a sound wave travels through the

medium

speed of sound in the body ranges between

500 m/s to 4000 m/s depending on the tissue

speed is determined only by the

medium

is speed adjustable

no

what is the speed of sound in soft tissue

Approximately 1540 m/s or 1.54 mm/us

speed of sound in air, water, and metals

approximately 330 m/s in air, 1480 m/s in water, and about 2,000 to 7,000 m/s in metals.

speed formula

speed = frequency × wavelength.

two characteristics of a medium affect the speed of sound

stiffness and density

stiffness describes the ability of an object to resist

compression when a force is applied.

density describes the relative _ of a material

weight

stiffness and speed are _ related

directly

Bulk modulus is the same as

stiffness

what is the opposite of stiffness

compressibility and elasticity

density and speed are _ related

inversely

sound travels faster in media with _ density

low

if two media are equally stiff, the _ medium will have a lower speed

denser

speed is determined by the _ and _

stiffness and speed

Stiffness increase, speed _

increases