Acoustic impedance is defined as the product of which two factors?

Acoustic impedance is a critical concept in ultrasound physics, representing how much resistance an acoustic wave encounters as it travels through a medium. It is defined specifically as the product of the speed of sound in a particular medium and the density of that medium.

In tissue, the speed of sound varies slightly depending on the specific characteristics of the tissue, such as its composition and physiological state, while the density reflects the mass per unit volume of the tissue. Together, these two factors (speed of sound and density) determine how much acoustic energy is transmitted or reflected at the interface between different tissues. This principle is fundamental in ultrasound imaging because it influences the generation of echoes, which are critical to forming the images we interpret during sonographic exams.

While other options touch upon related concepts, they do not correctly define acoustic impedance. For example, frequency impacts penetration and resolution in ultrasound but is not part of the acoustic impedance formula. Understanding this relationship helps in comprehending the interactions of ultrasound waves with different tissues, which is essential for effective imaging.