| English Wikipedia - The Free Encycl... |
Acoustic hailing device
An acoustic hailing device (AHD) is a specialized loudspeaker that emits high-power sound waves for communicating at a distance. AHDs vary in design, output, and usability.
| See more at Wikipedia.org... |
© This article uses material from Wikipedia® and is licensed under the GNU Free Documentation License and under the Creative Commons Attribution-ShareAlike License
