Breaking Sound Barriers: an article on aids for the hearing-impaired (May 19), stated that a system of sign graphics had been created at Longwill School in Birmingham. Although the school works with the software, it was in fact developed in Leeds, inspired by work reported at a conference by a deaf teacher from Derby. Sign Graphics software en-ables deaf pupils to record their own language and can be obtained for Pounds 55 from Semerc: 0161 627 4469.