假声（意大利语：Falsetto，为意大利语「falso(虚假的)」的暱称变格），又称假音，可落实音域内每一个音，常用以发出正常音域上限一个八度内的音。是通过声带的韧带边缘部分或整体振动产生。虽然常视作歌唱技巧，实际上也常常出现在日常交谈中，也是言语治疗学中归类的四大发声方法之一。

假声明显带有呼吸声，且常被认为类似笛音，很少出现泛音。比起正常发声方式，以假声说话、唱歌，在音色、音质、音量等方面的变化明显受更多限制。过去，由于女性假声较男性变化更不明显，因而常认为假声是男性的特有发声方式，其实无论男性女性都能发出假声。 而意大利的原词「falsetto」，常用来形容令歌手能够唱出超越自己正常音域上限的高音的技术。

Falsetto [falˈsetto] (Italian diminutive of falso, "false") is the vocal register occupying the frequency range just above the modal voice register and overlapping with it by approximately one octave.

It is produced by the vibration of the ligamentous edges of the vocal cords, in whole or in part. Commonly cited in the context of singing, falsetto, a characteristic of phonation by both men and women, is also one of four main spoken vocal registers recognized by speech pathology.