Here's why:

* High-frequency sound waves: Ultrasound uses sound waves with frequencies beyond the range of human hearing (typically above 20 kHz).

* Visualizes structure: The sound waves are emitted and reflected back to the device, creating an image based on the differences in density and elasticity of the tissues they encounter.

* Strikes tissues of different densities: The sound waves travel through the body and reflect back differently depending on the density of the tissues they encounter. This allows for the visualization of internal organs, blood vessels, and other structures.

Let me know if you'd like to know more about how ultrasound works or its different applications!