Simplify the following text for a Grade 10 native English-speaking person.
Original: Stanley Smith Stevens ( 4 November 1906 -- 18 January 1973 ) was an American psychologist who founded Harvard 's Psycho-Acoustic Laboratory and is credited with the introduction of Stevens ' power law .
Simplified: Stanley Smith Stevens ( 4 November 1906 -- 18 January 1973 ) was an American psychologist . He founded Harvard 's Psycho-Acoustic Laboratory and introduced Stevens ' power law .