Voice Phenomena - Booklet 4

Sunflower Booklet Series, Book 4: Voice Phenomena (Blue pamphlet) by Marilyn Awtry - June 2016

Spiritualist trumpet and voice phenomena, a part of physical mediumship, involves the use of a trumpet-shaped device to facilitate spirit voices and other physical manifestations during séances. Spirits can utilize the trumpet to amplify their voices, sometimes even causing it to levitate and move around the room. 
Spiritualist trumpets, typically lightweight cones made of metal (like tin or aluminum), were used in séances to amplify spirit voices. 
It is theorized that ectoplasm, a mysterious substance emanating from the medium, was involved in amplifying the voice and causing the trumpet's movement. 
The use of the trumpet is often associated with "direct voice mediumship," where spirits are believed to speak directly, independent of the medium's voice.