Learn about the sensitive skin of alligators on this Moment of Science.
While most flies don’t have the ability to hear, a certain parasitic fly has a hearing system that is so exact in pinpointing a sound’s origin that it rivals the exceptional ears of owls and cats.
When the bottle vibrates, the water inside has to vibrate with it. Having to move all that water slows down the vibrations of the glass and that in turn slows down the frequency of the sound waves, producing a lower pitch. Adding more water slows down the bottle’s vibrations even more, creating an even lower pitch.