Assertion: microphone's frequency response | /r/HasSubevent | their abandonment
Facets:
value: in those applications
type: LOCATION
value: by the late 1920s
type: TEMPORAL
Source sentences:
text: Carbon microphones, usually modified telephone transmitters, were widely used in early AM radio broadcasting systems, but their limited frequency response, as well as a fairly high noise level, led to their abandonment in those applications by the late 1920s.