Acoustic Waves and Properties Flashcards

Which acoustic parameter is determined solely by the medium through which sound travels?

Answer: Propagation speed

Propagation speed depends entirely on the medium's density and stiffness, not on the sound source.

If the propagation speed of sound increases while frequency remains constant, what happens to wavelength?

Answer: Wavelength increases

Wavelength = propagation speed / frequency, so an increase in speed with constant frequency results in a longer wavelength.

The acoustic impedance of a tissue is defined as the product of:

Answer: Density and propagation speed

Acoustic impedance (Z) = density (ρ) × propagation speed (c), measured in Rayls.

Rarefaction in a longitudinal acoustic wave refers to:

Answer: A region of decreased particle density

Rarefaction is the low-pressure, low-density phase of a longitudinal wave where particles are spread apart.

Which unit is used to quantify acoustic intensity?

Answer: Watts per square centimeter (W/cm²)

Acoustic intensity represents power per unit area and is expressed in W/cm² or mW/cm².

In diagnostic ultrasound, increasing the frequency of the transducer will:

Answer: Decrease penetration depth and increase axial resolution

Higher frequency shortens wavelength, improving axial resolution, but also increases attenuation, reducing penetration depth.

The period of a sound wave is the reciprocal of:

Answer: Frequency

Period (T) = 1 / frequency (f); a 1 MHz wave has a period of 1 microsecond.