What is the acoustic resistance to sound traveling in a medium known as?

The correct term for the acoustic resistance to sound traveling in a medium is impedance. Impedance combines both the density of the medium and the speed of sound within that medium to quantify how much resistance sound encounters as it travels. In more technical terms, impedance is a measure of how much sound pressure is needed to produce a certain particle motion within the medium. It is critical in understanding how sound interacts with different media, particularly in diagnostic ultrasound applications, as it influences the efficiency of sound transmission and reflection at boundaries between different tissues.

In contrast, density refers to the mass per unit volume of a substance and is a component of impedance but does not encompass the entirety of acoustic resistance. Speed refers to how fast sound waves travel through a medium, which is also part of the equation defining impedance but does not represent resistance directly. Attenuation describes the loss of intensity of sound as it travels through a medium due to absorption, scattering, or reflection, but it does not pertain specifically to the concept of resistance to sound flow. Understanding impedance is essential for sound propagation and imaging quality in ultrasound sonography.