We love glass harps – instruments made from wine glasses that are filled with different amounts of water to create a series of desired pitches. In The Inverted Glass Harp, Dan Quinn shows us that empty glasses can also create beautiful tones when they’re immersed in water. Why do these glasses change pitch as the amount of water within or around them changes? From his site:
The inverted harp has less range and can only play one note at a time, but it also has some key advantages: it’s quicker to set up, it’s much cheaper, and it can play “slides” like a trombone. Both the normal and inverted harp basically work the same way. The glass has to accelerate the neighboring water and therefore behaves as if it has more mass; scientifically speaking, you’d say the glass some additional “virtual mass” when it’s full (or submerged). The virtual mass lowers the resonant frequency of the glass, so it produces a lower pitched sound.