Describing Sound Waves

These flashcards cover the key vocabulary terms and definitions relevant to the topic of sound waves in the context of physics, specifically focusing on ultrasound.

Period

Time taken to create a single cycle of a sound wave; measured in microseconds (µs), seconds, etc.

Frequency

Number of cycles occurring in one second; measured in Hertz (Hz).

Wavelength

Distance occupied by one complete cycle of a sound wave; measured in mm or m.

Amplitude

Bigness of a wave; difference between peak and average or valley and average.

Power

Rate of energy transfer in a sound wave; measured in watts.

Intensity

Concentration of energy in a sound beam; relating power and area; measured in W/cm².

Speed of Sound

Rate at which sound travels through a medium; measured in m/s or mm/µs.

Infrasound

Sound with a frequency below 20 Hz.

Audible Sound

Sound frequencies between 20 Hz and 20 kHz.

Ultrasound

Sound with a frequency greater than 20 kHz.

Reciprocal relationship

A relationship where one variable increases as the other decreases.

Sound wave source

The combination of ultrasound system and transducer emitting sound waves.

Medium

Material or tissue through which sound travels.

Typical value of period in ultrasound

0.06 to 0.5 microseconds (µs).

Typical frequency in ultrasound

2 MHz to 15 MHz.

Human hearing range

20 Hz to 20 kHz.

Hertz (Hz)

Unit of frequency equivalent to one cycle per second.

Power and amplitude relationship

Power increases with amplitude squared and decreases inversely.

Intensity and amplitude relationship

Intensity is proportional to the amplitude squared.

Propagation speed dependence

Speed of sound depends only on the medium.

Wavelength and frequency relationship

Wavelength is inversely proportional to frequency.

Typical speed of sound in soft tissue

1540 m/s.

Units for intensity

Measured in watts per square centimeter (W/cm²).

Effects of amplitude on power

Power increases when amplitude increases.

Schrodinger equation

An equation describing how quantum states evolve.

Stiffness

Ability of an object to resist compression.

Density

Mass per unit volume of a medium.

Elasticity

Ability of an object to return to its original shape after deformation.

Compressibility

Measure of how much a substance can be compressed.

Soft tissue average speed

1,540 m/s.

Speed of sound in water

1,480 m/s.

Sound travels fastest in

Stiff materials with low density.

Intensity is doubled

When power is doubled, intensity is also doubled.

Shorter wavelengths are created by

High frequency sound.

Complementary units for frequency

MHz, mm, microseconds (µs).

Amplitude defined

Measured from baseline to peak or valley.

Peak-to-peak amplitude

Difference between maximum and minimum values of a wave.

Beam area and intensity relation

Intensity equals power divided by area.

Questions concerning parameters

Identify units and characteristics of frequency, intensity, wavelength.

Acoustic variables

Frequency, density, particle motion, pressure.

Acoustic parameters

Frequency, density, pressure, period.

Speed of sound alters with

Changes in stiffness and density of the medium.

Proportional change rule for power and amplitude

When amplitude doubled, power increases by a factor of four.

Speed of sound in metals

2,000 to 7,000 m/s.

Sound pressure level related to

Amplitude and intensity.

Ultrasound in diagnostics

Higher frequencies improve image quality.

Amplitude adjustments

Can be adjusted by the sonographer.

Period adjustments

Cannot be adjusted, determined by the source.