Sound needs a medium to pass through. It requires substance to vibrate and propagate the sound. Not surprisingly, different substances propagate sound differently. The way we hear a sound depends very much on the matter through which it is passed.
One of the reasons our own voices sound different to us when recorded is that we are used to hearing our voice propagated through the bone and flesh of our skull (ick). But it sounds a little different when propagated through air. But air is the medium we’re used to. And actually, it is not that great a medium. Sound loses a lot of power and scope when it moves through air.
A wire coat hanger banged against a surface sounds unimpressive when the sound passes through air, but sounds like a highly resonant gong when the sound passes through the hanger, the string, and your fingers. Try it!
What you need:
A wire coat hanger
About 1 metre of string
Two fingers and two ears