A hollow telephone receiver comprises a body, a vibrating diaphragm, a coil, a front piece, a magnet, a yoke, a sound adjusting cloth and a terminal plate. The vibrating diaphragm, coil, front piece, magnet, yoke, sound adjusting cloth and the terminal plate are placed into the body sequentially. Thus, the coil winds the cylinder at the lower end of the yoke and is located within the front piece and the magnet. While the upper circular hole at the upper end of the yoke is adhered with the sound adjusting cloth and the terminal plate so that after a hollow telephone receiver is assembled, a hollow portion is formed at the center thereof. Therefore, as a sound is expanded and compressed by the vibration of the vibrating diaphragm. The amplitude of the sound wave will complete concentrate at the hollow portion and is collected at the lower portion of the cylinder of the yoke. Moreover, by the S pole and N pole at the upper and lower ends of the magnet, the magnetic strength is increased effectively so as to enhance a current. Since the sound is amplified by passing through the hollow portion, a steadier audio response is obtained.

A radio or telephone handset configured with the usual transmitter and receiver ends and connecting handle is designed to have physical characteristics well adapted in its acoustic characteristics to complement noise cancellation circuitry. The receiver speaker is mounted in the receiver cap, and the cap is built with a domed, apertured earpiece extending from the exterior surface of said receiver cap. The dome fits into a user's outer ear, thereby to aid in positioning said handset on a user's ear. Openings radially placed on said receiver cap exterior surface and surrounding said earpiece, define an acoustic grill through which signal from said receiver speaker is passed substantially directly to said user's ear canal. Noise absorbing material is placed at strategic locations within the handset interior.

An overhead loudspeaker system is achieved which controls and shapes the ultimate acoustical wave form produced thereby, by providing at least one loudspeaker driver, mounted in a housing or enclosure, and a uniquely constructed wave shaping and controlling member formed as an integral component of the speaker assembly. In this way, broad band, acoustical wave shaping and control is realized. In accordance with a present invention, the wave shaping/controlling member is cooperatively associated with the drivers of the loudspeaker in a way which effects the critical acoustical loading and atmospheric coupling thereof, while controlling and shaping the ultimate acoustical wave form so that a hemispherical polar coverage pattern results. In the preferred configuration, the polar coverage pattern produced by the present invention is provided across the loudspeaker system's entire power bandwidth, beginning at an approximate distance of about three times the diameter of the acoustical source.

An electromagnetic transducer has a moving coil, a diaphragm and a magnet system enclosed within protecting covers. It includes an inset placed between the magnet system and the front cover. The inset is made of a non-magnetic, electrically insulating material and is provided with an aperture.

A method of manufacturing a telephony earpiece is provided. The method includes providing a speaker diaphragm and constraining the speaker diaphragm using a cap to provide a thin cavity between the cap and the diaphragm. The first resonance peak of the diaphragm/cavity system is damped by a first slow leak in the cap. The frequency response is built up using a rear resonator in the cap and the high frequency end response is enhanced using a front resonator on an opposite side of said diaphragm as said cap. Positioning of these resonator holes is an important factor. The earpiece is tuned using a second leak to adjust amplitude of low frequency end response.