Who read the Book of the Law aloud to the assembly in Nehemiah 8?

Answer: Ezra

The people asked Ezra the scribe to bring out the Book of the Law of Moses, and he read it aloud before the assembly.

“At that time all the people gathered together in the square before the Water Gate, and they asked Ezra the scribe to bring out the Book of the Law of Moses, which the LORD had commanded for Israel.”— Nehemiah 8:1 (BSB)