Choose the words that correctly complete the sentences.
There are many stories that exist of opera singers breaking wine glasses with their voices.
The vocalist must match the (pitch / volume / intensity / density) of their voice to the natural (mass / thickness / loudness / frequency) of the glass. The louder the singer can go, the more (volume / intensity / pitch / density) the vibrations have, and the better the chance of shattering the glass.
Your answer: