Eber Howe says that Martin Harris recorded that a screen was between them or JS would be in a different room during the dictation of the translation.
Eber D. Howe, Mormonism Unvailed (Painesville: E.D. Howe, 1834), 14
He [Howe] says he [Harris] wrote a considerable part of the book, as Smith dictated, and at one time the presence of the Lord was so great, that a screen was hung up between him and the Prophet; at other times the Prophet would sit in a different room, or up stairs, while the Lord was communicating to him the contents of the plates. He does not pretend that he ever saw the wonderful plates but once, although he and Smith were engaged for months in deciphering their contents.