the branch of instrument-making dealing with the development and manufacture of devices for the correction and compensation of hearing defects and resulting speech defects; also, the equipment used for such correction and compensation.
Aural prosthetics draws upon many fields, including the physiology of higher nervous activity, the physiology of analyzers, the education of the deaf, otorhinolaryngology, communications theory, and electronics. It deals mainly with the amplification of speech and other sounds that can be perceived by residual hearing and the conversion of sounds into visual and tactile signals.
Aural prosthetics makes it possible to improve the education of children with impaired hearing, to widen the field of professions employing the deaf, and to help people with hearing defects cope with work and everyday life.
People with impaired hearing may perceive sound by means of various sound amplification systems: monaural amplification, amplification with automatic volume control, selective frequency amplification, and amplification with spectral conversion (trans-posers). The most common amplification device is the hearing aid. Amplification apparatus designed for group use are employed in classrooms. Individual training sessions for development of hearing and speech are conducted using devices with a wide range of sounds and frequencies; this equipment is used separately on each ear. When it is necessary for the person being trained to move freely, for example, in rhythmics lessons, wireless amplification systems with magnetic fields and telephone coils are used. Auditory signals are converted into vibrations in cases of severe hearing impairment, when amplification proves ineffective. Apparatus that transform speech into visual signals are used chiefly for teaching correct pronunciation. Speech signals depicted on a screen, for example, an oscillogram or spectrogram, allow the student to compare his pronunciation with that of the teacher.
Devices presently being manufactured include various informational systems using colored signals, systems that emit special alarms, and information displays. Devices for home use alert the deaf person to such important sounds as the ring of a doorbell or an infant’s cry by setting off a flashing light. Deaf people may communicate by telephone not only by means of amplification devices but also with the aid of simple telephone attachments for the reception and transmission of signals in Morse code, as well as teletype printers and facsimile machines.
REFERENCESTsukerman, I. V. Besedy o glukhote i tekhnike, pomogaiushchei glukhim. Leningrad, 1973.
Slezina, N. F. Primenenie tekhnicheskikh sredstv v obuchenii glukhikh proiznosheniiu. Moscow, 1975.
V. D. LAPTEV and V. I. LUBOVSKII