A person is not incapacitated merely he/she is Deaf or Dumb or Blind provided he/she is able to know what he/she does.
Earlier person born Deaf and dumb was incapable of making a Will, but with the advancement in methods of educating such persons, the position no longer holds.
Testator who is deaf and dumb can make his will by communicating his testamentary instructions by signs and motions, to an acquaintance, who can prepare a will in conformity with such instructions, which will be afterwards duly executed by the testator. For proving the same the court requires an affidavit from the writer of the will giving the nature of signs and motions by which the instructions were conveyed to him.
Blind person is capable of making a will of his/her property, but he/she cannot attest a Will or codicil.