head voice

/HH EH1 D V OY1 S/
noun
  1. 1

    A kind of voice of high pitch and of a thin quality ascribed to resonance in the head; voice of the thin register; falsetto. In producing it, the vibration of the cords is limited to their thin edges in the upper part, which are then presented to each other.

Source: https://en.wiktionary.org/wiki/head%20voice