Messa di voce

Messa di voce [ˈmessa di ˈvoːtʃe] (Italian, "placing of voice") is a musical technique that involves a gradual crescendo and diminuendo while sustaining a single pitch. That is, a note is sung at a quiet volume, gradually and smoothly made louder until it reaches a high volume, then similarly made quiet again. The technique can be used on many instruments, but is perhaps best known for its use among singers.