Why does pitch change as salt dissolves in water?

[gdaigle]

I have a cold and need to gargle. I put a tsp of table salt into a waterglass, add warm water and stir. I immediate hear the ting-tang pitch of the spoon-hitting-glass slowly lowering as I stir. The solution is now cloudy. As I continue to stir the pitch now rises back to its beginning point as the solution begins to clear.

Why?

 

[gdaigle]

I should add ... I then tried the same (adding warm water, stirring) but without adding the table salt. There was no (or little) pitch change.

 

[nazgjunk]

Well, obviously it's the solid salt crystals changing the pitch. As you know, sound travels faster through solids than it does through water (well it usually does). I guess different materials also conduct (is that the right word?) different frequencies in different ways.