Ultrasound Physics and Instrumentation

A set of flashcards covering key concepts from Ultrasound Physics and Instrumentation, including definitions, equations, and principles of sound wave behavior.

What is the frequency range of infrasound?

Below 16 Hz.

What is the frequency range of Audible Sound?

Between 16 Hz and 20 kHz.

What frequency range does ultrasound cover?

Above 20 kHz.

What is the equation for calculating distance?

Distance = Rate x Time (d = rt).

What is the speed of sound in tissue?

Approximately 1540 m/s.

What unit is used for acoustic pressure?

Pascals (Pa).

What is the relationship between power and amplitude?

Power is proportional to the amplitude squared (P ∝ A²).

What is meant by 'direct proportionality' in variables?

If one variable increases by a certain percentage, the other increases by the same percentage.

What do compressions in a sound wave represent?

Areas of high pressure and density.

How does temperature affect sound propagation?

Increases in temperature generally increase sound speed.

What is the unit of intensity in sound waves?

Watts per square centimeter (W/cm²).

What does a high frequency indicate about wavelength?

A shorter wavelength.

What is the definition of amplitude in a sound wave?

The difference between the minimum and average value of an acoustic variable.

What happens to intensity when amplitude is doubled?

Intensity increases by a factor of four (4X).

What is the physical distance of one complete cycle called?

Wavelength (λ).

What is the reciprocal of frequency related to?

Period (T); T = 1/f.

Describe what occurs in the rarefaction phase of a sound wave.

Lower particle concentration (lower density) results in areas of lower pressure.

What does the Sine Wave represent in sound waves?

The cyclic nature of sound pressures.

Which variable affects the propagation speed of sound the most?

Stiffness (or bulk modulus).

What is meant by ‘reciprocal’ in the context of a number?

The inverse of a number where two numbers multiplied together equal one.

What is the main effect of increasing a medium's elasticity on sound speed?

Decreases sound speed.

What is the relation of frequency to period?

Inversely related; as frequency increases, period decreases.

How is sound defined as a wave?

As a mechanical wave where particles in a medium vibrate.

What type of wave is sound?

Mechanical longitudinal wave.

What is the relationship between sound wave frequency and human hearing?

Humans can hear frequencies between 20 Hz and 20 kHz.

What does heavy dampening of sound indicate about the medium?

Higher attenuation of sound waves.

What does it mean when waves are 'in phase'?

Waves reinforce each other.

What occurs when waves are 'out of phase'?

Waves interfere destructively.