Simplify the following text for a Grade 8 native English-speaking person.
Original: In the late 1950s and early 1960s , the development of the Westrex single-groove stereophonic record cutterhead led to the next wave of home-audio improvement , and in common parlance , stereo displaced hi-fi .
Simplified: In the late 1950s and early 1960s , Westrex invented the single-groove stereophonic record . This led to the next wave of home audio improvement .