Assertion: speaker's design | /r/HasProperty | popularized in the 1920s
Facets:
value: as baldwin mica diaphragm radio headphones
type: OTHER
Source sentences:
text: Although this reduces its efficiency, this design can still produce more sound from less power than any other.[clarification needed] Popularized in the 1920s as Baldwin Mica Diaphragm radio headphones, balanced armature transducers were refined during World War II for use in military sound powered telephones.