What is the term that describes an echo from a sound wave traveling from one medium into another?

The term that describes an echo from a sound wave traveling from one medium into another is acoustic impedance. Acoustic impedance is a property of a medium that affects how much sound energy is transmitted or reflected when sound waves encounter a boundary between two different materials. When sound waves travel from one medium (like air) into another (like water), the difference in acoustic impedance between the two can lead to reflection, which is perceived as an echo. The amount of sound reflected versus transmitted is determined by the impedance of both media, making acoustic impedance essential in understanding sound wave behavior at interfaces.

Understanding acoustic impedance helps explain why certain materials may absorb sound, while others reflect it better, leading to the phenomenon of echoes. This is particularly important in various fields, including medical imaging (ultrasound) and architectural acoustics, where controlling sound behavior is crucial.