Terumos 1:2

A deaf person who can speak but not hear may not separate terumah but if he did, the terumah is valid. The deaf person referred to by the Sages (as in mishna 1:1) can neither hear nor speak.

Terumos 1:3

If a minor has reached the age of education but has not yet produced two pubic hairs, Rabbi Yehuda says terumah separated by him is valid. Rabbi Yosi says that if the minor is not yet old enough to be obligated in vows (12 years and a day for a boy; 11 and a day for a girl), his terumah is not valid; after that, it is.