Assertion: digital recording | /r/HasProperty | the most important milestone
Facets:
value: arguably
type: DEGREE
Source sentences:
text: Between the invention of the phonograph in 1877 and the first commercial digital recordings in the early 1970s, arguably the most important milestone in the history of sound recording was the introduction of what was then called electrical recording, in which a microphone was used to convert the sound into an electrical signal that was amplified and used to actuate the recording stylus.