Semi-occluded vocal tract (SOVT) techniques may be used to facilitate voice production in the higher pitch range. SOVT techniques include phonating into straws, lip or tongue trilling, and producing multiple speech sounds such as nasals /m/, /n/, voiced fricatives (i.e. /z/, /v/), and high vowels such as /u/ and /i/. There are two exercises that are often used: producing a pitch glide that goes from the middle of the pitch range to the upper pitch range; and a "messa di voce" exercise, where the voice goes from soft to loud to soft again. SOVT techniques have the individual prolong their voice at a higher pitch, which may help make voice production at a higher, non-habitual pitch easier and more efficient.