A method of coupling a speaker diaphragm of the listening space by an expanding air column that has a small throat and a large mouth.
"I truly cannot thank you enough for bringing the voice of my father-in-law back to life. We had carefully treasured the old reel-to-reel tapes sent from my husband's father to the family while he was serving in the Vietnam War. Our old machine didn't work anymore and the tapes were becoming very brittle. We feared losing this piece of history ..."