Abstract: An anterior wall of a case has a central aperture and two discharge apertures extending from the central aperture. There is an anterior chamber inside the anterior wall. Moisture such as rain water, even if entering the anterior chamber, is smoothly discharged out of the case from the discharge apertures along an inner face of the anterior chamber. As a result, it becomes possible to prevent the moisture from remaining and attaching to a first diaphragm in the anterior chamber and to prevent degradation of sound pressure collected by the first diaphragm through the central aperture and the discharge apertures.

Abstract: An anterior wall of a case has a central aperture and two discharge apertures extending from the central aperture. There is an anterior chamber inside the anterior wall. Moisture such as rain water, even if entering the anterior chamber, is smoothly discharged out of the case from the discharge apertures along an inner face of the anterior chamber. As a result, it becomes possible to prevent the moisture from remaining and attaching to a first diaphragm in the anterior chamber and to prevent degradation of sound pressure collected by the first diaphragm through the central aperture and the discharge apertures.

Abstract: A small and high-performance waterproof speaker which can be manufactured inexpensively by decreasing the number of components. Front face of a case (1) is sealed hermetically by a water resistant diaphragm (2) from which a voice coil (3) is projecting inward and a magnetic circuit part (5) having a part (6a) being fitted to the voice coil (3) and a permanent magnet (8) is secured to a first resilient plate (4) provided in the case (1). The first resilient plate (4) is provided with a plurality of through holes (18) and the fitting part (6a) is coupled with the diaphragm (2) through a first coupling member (13) of resilient material. On the other hand, an inertial member (12) is secured to a second resilient plate (11) disposed, oppositely to the first resilient plate (4), in the case (1) and the second resilient plate (11) is coupled with the first resilient plate (4) through a second coupling member (14) of resilient material.

Abstract: An underwater communication apparatus is provided which enables safe and clear speech transmission. An exhalation pipe which defines an acoustic space for communicating with an interior space of a mouthpiece is connected at one end to a site adjacent a breathing port of the mouthpiece. An exhaust valve which allows the flow of air only from the mouthpiece toward an exhaust port of the exhalation pipe is provided adjacent the exhaust port. A sound receiver portion having a capacitor microphone is provided within the exhalation pipe at a site upstream of the exhaust valve. When voice is uttered while the mouthpiece is held in the mouth, exhaled air is emitted from the exhaust port through the exhalation pipe and the exhaust valve, so that the capacitor microphone is less liable to noise trouble due to bubbles produced at the exhaust port, or on the downstream side. Speech transmission is made underwater by a waterproof speaker on the basis of an output of the capacitor microphone.