What term describes the factor that determines reflection or transmission of ultrasonic energy at an interface?

The term that describes the factor determining the reflection or transmission of ultrasonic energy at an interface is acoustic impedance. Acoustic impedance is defined as the product of the material's density and the speed of sound within that material. When ultrasonic waves encounter the boundary between two different materials, the difference in acoustic impedance at the interface influences how much of the energy is reflected back into the first medium and how much is transmitted into the second medium.

Understanding acoustic impedance is crucial for effective ultrasonic testing because greater differences in acoustic impedance between the two materials will lead to higher levels of reflection. This principle is essential for optimizing the detection of flaws and assessing material integrity. Hence, the relationship between acoustic impedance and energy behavior at interfaces helps practitioners interpret ultrasonic testing results accurately.