Conversation so far:
When did Pharrell Williams sign on to the Voice?
Pharrell Williams was a coach for the seventh season of The Voice.
What season was Pharrell Williams a coach for the voice?
Pharrell Williams was a coach for the seventh to tenth seasons of The Voice.
What is Pharrell Williams presently doing since the voice?
Pharrell Williams is set to produce five songs for Walt Disney Pictures's The Lion King, marking his third collaboration with composer Hans Zimmer.
Has Pharrell Williams won any awards from 2014-present?
In 2014, he received an Academy Award for his song Happy.

Question: Who did he coach on the voice?
Self-contained rewrite: Who did Pharell Williams coach on the voice?