Improvements in and relating to the construction of sound boxes, volume chambers or trumpets used in connection with gramophones, loud speakers, musical instruments and the like

摘要

250,669. Vucasovitch, H. Jan. 15, 1925. Drawings to Specification. Ear instruments.-The Piovisional Specification states that the invention, which relates to a sound-magnifying structure comprising walls built up of two or more layers of material separated by an air space or spaces, is applicable to ear trumpets.