Ultrasonic sound waves can indeed pass through solid objects, including hard materials, under certain conditions. The ability of sound waves to pass through solids depends on various factors, including the frequency of the sound wave, the properties of the material, and the thickness of the object.
When an ultrasonic wave encounters a solid object, several things can happen:
Transmission: If the material is relatively thin and the frequency of the ultrasonic wave is within a range that the material can transmit, the sound wave can pass through the object. Some energy may be absorbed or attenuated, but a significant portion of the wave will continue through the material. The amount of energy transmitted depends on factors such as the material's density, elasticity, and acoustic impedance.
Reflection: When the ultrasonic wave encounters an interface between two materials, a portion of the wave can be reflected back. The amount of reflection depends on the acoustic impedance mismatch between the materials. If the impedance mismatch is significant, a larger portion of the wave will be reflected, causing echoes or reflections.
Absorption: Some materials can absorb ultrasonic waves, converting their energy into heat. The absorption characteristics depend on the specific properties of the material and the frequency of the wave. Higher frequency ultrasonic waves tend to be absorbed more easily than lower frequency waves.
The ability of ultrasonic sound waves to pass through solid objects is utilized in various applications, such as medical imaging (ultrasound), non-destructive testing, and industrial inspections. By analyzing the transmission, reflection, and absorption of ultrasonic waves, it is possible to gather information about the interior of an object or detect flaws within it.