A Method for Maintaining in a Public Address System the Illusion that the Sound Comes from the Speaker's Mouth
William M. Hall · The Journal of the Acoustical Society of America · 1936
As described in the paper by Professor Fay, it is possible to maintain the illusion that the sound comes from the speaker's mouth by arranging the reproducing system so that the original sound reaches the listener's ear before the reproduced. A study has been made of this effect to determine some of its limitations and possibilities.