Acoustic impedance is determined by which medium properties?

• A. Frequency and Propagation Speed
• B. Density and Interface Size
• C. Density and Propagation Speed
• D. Angle of Incidence and Media Propagation Speed

Answer: (C)

Acoustic impedance is the opposition a medium offers to a sound wave, and in a uniform medium it is given by Z = ρ c, the product of density (ρ) and the speed of sound (c) in that medium. Because impedance depends on both how much matter there is to move and how fast sound travels through it, the intrinsic medium properties are density and propagation speed. Frequency doesn’t set impedance—it affects wavelength and attenuation instead. Likewise, angle of incidence or interface size are boundary or geometric factors that influence how waves reflect or transmit at boundaries, not the medium’s inherent impedance. So the medium properties that determine acoustic impedance are density and propagation speed.