Can ultrasonic waves travel through solid objects?


Joined Jul 24, 2018
For perspective, the speeds of sound in a few materials (at roughly room temperature):
Air: 343 m/s
Water: 1500 m/s
Wood (and some forms of steel): 3850 m/s
So solids (or liquids) are exceptional conductors of sound. You may get weird results at resonances, but in general, sound travels pretty well through "non-air" objects.
The only issue where sound waves have a hard time traveling through is the interface between two mediums. If my approximations are correct (and it's possible they're not), about 39% of sound is reflected off the air-to-water interface, and 70% off the air-to-wood interface, which may make it seem that sounds (ultrasonic or otherwise) have a hard time traveling through solid objects.

Delta Prime

Joined Nov 15, 2019
I read somewhere that ultrasonic waves have a hard time travelling through solid objects, if this is true, then how do dolphins communicate?
Dolphins can also focus the ultrasonic waves to very small point and make the inside of fish turn into mush. It's from observation of dolphins that humans got the idea of breaking up little calcium rocks or stones in the human kidney.
A beam of ultrasound shock waves from outside the body is focussed onto the stone, which breaks into smaller pieces. The smaller fragments that remain can then pass through the urinary tract.