Also called a horn. A tube of varying cross section having different terminal areas, which change the acoustic impedance to control the directivity of the sound pattern.
"Dear CVC Productions Thank you for your prompt processing of my 1967 LP home recording of my long deceased wife,s guitar and singing. It amazed me that this long hidden and abused LP could be restored,with scratches and blemished removed. As per my instructions,the color cover together with the titles to the songs were faithfully ..."