Context: Bell and his assistant Charles Sumner Tainter jointly invented a wireless telephone, named a photophone, which allowed for the transmission of both sounds and normal human conversations on a beam of light. Both men later became full associates in the Volta Laboratory Association.

Question: What did Bell call his cord-free phone?
Answer: photophone

Question: Who did Bell invent the cord-free phone with?
Answer: Charles Sumner Tainter

Question: What did Bell's cord-free phone use to transmit messages?
Answer: light

Question: What lab association did Bell and Tainter both eventually join?
Answer: Volta Laboratory Association

Question: In the photophone, light carried sound and what?
Answer: normal human conversations