Hearing development apparatus `` Mars-1 ''.

Acoustic systems, passive or active, as well as electro-acoustic units, hearing aids, electric megaphones, intercoms ...Hearing AidsThe small-sized apparatus for the development of hearing for individual and collective use "Mars-1" has been produced since 1984. The device was developed by a group of employees of the hearing-speech laboratory of the Leningrad Regional Institute of the Deaf. No information available!