. "1981Z"^^ . "American physicist" . . . . . . . "1981-07-23Z"^^ . "Fletcher, Harvey"@en . "1884-09-11Z"^^ . "1884Z"^^ . . . . . . . . "Harvey Fletcher (September 11, 1884 \u2013 July 23, 1981) was an American physicist. Known as the \"father of stereophonic sound\". He is credited with the invention of the audiometer and the first electronic hearing aid. He is remembered as a trail-blazing investigator into the nature of speech and hearing, and for his numerous contributions in acoustics, electrical engineering, speech, medicine, music, atomic physics, sound pictures, and education."@en . "Harvey Fletcher"@en . .