While searching Google for info whether the World Pacific Studio used a plate, a dedicated chamber or just the hallway for reverb I found this:

Ring-A-Ding Ding – 1961 (Part five of the pre-history of “The Reprise Sound”)

Recordings, Jessica Marciel: Las Vegas Vocal Training : Las Vegas Vocal Training: Singing Lessons

Avaaz – A new plan to save the planet

BREAKING: You Know That TED Talk You Weren’t Supposed To See? Here It Is.