What term describes the gradual loss of sonic energy as ultrasonic vibrations travel through a material?

The term that describes the gradual loss of sonic energy as ultrasonic vibrations travel through a material is known as attenuation. Attenuation encompasses various factors, including absorption, scattering, and divergence of the sound waves, that contribute to the decrease in intensity of the ultrasonic signals as they propagate through different media. This phenomenon is critical to understanding how effectively ultrasonic testing can detect flaws or measure thickness in materials, as greater attenuation can reduce the clarity and strength of the received signals.

In contrast, while terms like loss and dissipation may capture a similar idea, they do not specifically refer to the mechanisms involved in the reduction of ultrasonic energy over distance. Propagation, on the other hand, refers to the movement of sound waves through a material without implying any loss of energy, making attenuation the most accurate and precise term for this concept in the context of ultrasonic testing.