Underwater speakers
Underwater speakers are available in different versions. What they all have in common is a special construction method to protect against moisture.
Splash-proof external speakers
Loudspeakers designed for outdoor use and approved for contact with rain and splash water. The membrane and bead are protected from contact with water and moisture. For high-quality outdoor loudspeakers, materials that are insensitive to water (e.g. Kevlar) are used. The penetrated water can also escape from the loudspeaker through these materials.
The actual protection class or degree of protection of loudspeakers is indicated by the internationally valid IP code (International Protection).
The housings of the outdoor speakers are usually made of aluminum or ABS plastic . The UV sensitivity is usually significantly reduced in plastic housings.
Saltwater protected speakers
Loudspeakers that are also approved for contact with sea or salt water. The housing, mounting bracket and other components of the loudspeaker are made of corrosion-resistant materials. With these speakers, too, the UV sensitivity of the housing parts is significantly reduced.
Underwater speakers
Apart from constructions that are based on splash-proof loudspeakers and are only suitable for outdoor use, underwater loudspeakers are operated under the surface of the water.
The speaker's voice coil is located in a fully encapsulated plastic or metal housing. The membrane is an integral part of the loudspeaker housing. Waterproof speakers have an electro-acoustic transducer that generates the electrical signal from the audio system into sound waves through the piezoelectric elements in proportion to the signal supplied to it. A loudspeaker essentially comprises at least one transformer which is connected to a piezoelectric ceramic element. The piezoelectric element is in contact with the membrane and this is in direct contact with the transmission medium.
Classic applications are e.g. B. Swimming pools in which the underwater speakers are installed directly in the pool. This enables bathers to enjoy music underwater.
Applications:
- Underwater sound (e.g. in diving schools , swimming pools, synchronized swimming, therapeutic applications)
- Use in clean rooms
- sonar
- Ultrasonic cleaning (mostly ferroelectric transducers)
Special features:
- Underwater speakers built into a swimming pool cannot be heard above the water surface.
- Due to the identical acoustic impedance of the membrane and the sound medium, the efficiency of underwater speakers is usually between 50% and 90% (air: typ. <1%)
- the necessary diaphragm stroke is much smaller due to the high density
- the wavelength in water is much greater (since the speed of sound propagation is 4.3 times greater than in equally warm air) and the attenuation is lower, so speakers under water have a much larger working range and fewer resonances.
Individual evidence
- ^ Bathtub blog.de. Retrieved December 29, 2014 .