I want to build a Underwater one way comunication device?

Basically what I intend building is a device,a mic placed in a reg/DV and linked by cord arms length to a sender/speaker.This would be placed against your buddies head and he could hear you speak. Obviously it would have to be submersable to about 15 meters. Any advice on gathering bits and parts and plans,would be much appreciated

NachoMahma8 years ago
. Since sound travels very well in water, there is really no need to mount the speaker to the diver, unless the ears are blocked. . Not sure, but I think piezo speakers are water-resistant. You don't need a full-range speaker for voice communications. Some research on telephones should give you an idea of the frequencies that are important (somewhere around 5KHz, IIRC, but double-check). . The rest is just a mic and small amplifier. 1-2 watts should be more than sufficient for arms-length distances.
I believe underwater "telephones" convert the audible sound to ultrasound before transmitting it through the water, since it travels better, with less losses. The receiver picks up the ultrasound and converts it back to audible frequencies.