When you pour a glass of water, why does the pitch of the sound of the water going into the glass get higher?

Question

When you pour a glass of water, why does the pitch of the sound of the water going into the glass get higher?

In: Physics

Answer 1

The sound you hear is the longest wavelength the sound can travel in the glass, jar, bottle or whatever you are filling up. The longer the distance, lower the pitch and vice versa. When you fill up a bottle, the distance the sound can travel in the bottle gets noticeably shorter as you fill it up.

If you have a container that is cylindricar in opposite way to a bottle, so that the top is wider than or as wide as the bottom, this effect doesn’t happen as noticeably because the longest distance stays the same. It still happens, but it’s less noticeable.