Abstract: A hearing aid for relieving high frequency hearing loss, includes a volume control that allows the user to gradually adjust and increase the degree of compensation at a pace which corresponds to their particular need. The volume control changes the slope of the response from a flat insertion gain response, when it is turned down, to a rising insertion gain, when it is turned up. Thus, the volume control is not a traditional gain control but a slope control by which the sound clarity can be adjusted.

Abstract: A telephone station including an optical display device fashioned as a display is provided. The display device is quickly and simply attachable by being pluggably connected to the telephone station by engagement of webs on the display device with springs in the telephone station.

Abstract: A dome speaker comprising a dome-shaped diaphragm formed of a highly rigid material such as titanium or a titanium alloy, and having at least one elongated cut-out portion which varies the rigidity of the diaphragm and prevents a dip in the anti-resonance frequency range and a peak in the high resonance frequency range of the dome speaker. The speaker also includes a voice coil bobbin connected to the diaphragm. Preferably, the diaphragm includes two elongated cut-out portions in parallel relation to each other and with a center portion of the diaphragm interposed therebetween. A reinforcing rib may be integrally formed at an end of each cut-out portion. The cut-out portion may be covered either by a peripheral member made of a soft material or by a loss stopper formed of a viscoelastic material.

Abstract: An audio-frequency electromechanical vibrator having a flat hollow case with a thin cover plate, a flat ring-shaped permanent magnet axially magnetized and a flat annular drive coil unit. The magnet and the coil unit are disposed in the case coaxial with one another and with an axial space therebetween. The magnet is fixedly mounted on the bottom of the case and the coil unit is elastically supported to the case by a spring plate so that the vibrator can generate strong vibrations without noise generation corresponding to a comparatively higher frequency component in an audio signal applied to the coil unit.