Conversation so far:
Was audio frequency amplification something Lee de Forest studied about?
One of Lee de Forest's areas of research was improving signal reception, and he came up with the idea of strengthening the audio frequency output from a grid Audion.
Are there any other interesting aspects about the Lee de Forest article?
In July 1913 AT&T purchased the wire rights to seven Audion patents for $50,000, disguising their identity. Lee de Forest hoped for more, but he was in bad financial shape.
Did Lee de Forest work alone in his research?
Careful research by Dr. Harold D. Arnold and his team at AT&T's Western Electric subsidiary helped to improve Lee de Forest's tube's design.

Question: What kind of things could be done with audio frequency amplification?
Self-contained rewrite: What kind of things could be done with audio frequency amplification?