How two children can talk to each other over distance without shouting by using two metal cans and a taut string?

Two children can communicate over a distance using two metal cans connected by a taut string because sound waves travel through the string. When one child speaks into their can, the vibrations from their voice cause the can to vibrate, sending these vibrations along the string to the other can. The second can then vibrates and produces sound waves that the other child can hear. This method is effective because the taut string carries the sound vibrations much better than air alone.