I am neither recommending nor rejecting the following book. I am simply saying that I stumbled across it. I have neither read it nor studied it.
Search with: The Name of God Y.eH.oW.aH Which is Pronounced as it is Written I Eh oU Ah Its Story GÉRARD GERTOUX
A search will find a free simplified version at Academia.edu and a Youtube video:
My current opinion is that prior to 70 CE the Sadducees operated the Jerusalem temple and those priests became to only people who could utter God's Holy Name on certain occasions. When the temple was destroyed, the Sadducees and their rituals ceased, to be overtaken in time by Rabbinic Judaism.