Acoustic amplifiers (hearing aids) for partially deaf persons; Apparatus for use in alleviating hearing disorders; Apparatus for use in testing hearing disorders; Electronic hearing apparatus with masking for tinnitus sufferers; Hearing aids; Hearing apparatus for the deaf; Hearing protectors; Listening apparatus for use by persons with impaired hearing; Medical hearing instruments; Medical instruments for use as aids to hearing; Medical instruments for use in relation to hearing; Programmable hearing aids