? sounds? most lizards use motion to hunt, very few times to they use sound to find anything but danger, like birds or bigger animals walking near by, even then they usually look around for shadows or feel for vibrations rather than hear....but it's an interesting concept.
(i can understand using it like sonar to find things under the ground tho, we humans use that too.)
If they're tuned to the same frequency might work somehow. Mixing an altered signal with a reference frequently gives a signal of the difference that's low enough to be heard. It's how radar usually works.