Tone Guard

An acoustic network has been developed for attenuating the sound, generated and radiated directly into the air by the vibrating parts of the phonograph pick‐up, which passes through the aperture between the door and the cabinet. The series elements are formed by the slit between the door and the cabinet. The shunt elements are formed by a wood strip fastened to the inside of the cabinet. The attenuation band extends from 1000 to 10,000 cycles. The attenuation is of the order of 15 decibels over that with the conventional door and cabinet. The network has been applied to both horizontal and vertical doors.