Please don't use abbreviations if you want good answers. I had to research it to find:
The Long Range Acoustic Device (LRAD) is a crowd control and distance hailing device developed by LRAD Corporation to send messages, warnings and deterrent tones over longer distances than normal loudspeakers.
According to the manufacturer's specifications, the systems weigh from 15 to 320 pounds (6.8 to 150 kg) and can emit sound in a 30° beam at 2.5 kHz. LRAD's largest system at maximum level can emit a warning tone of 153 dBSPL measured at 1 meter while the smallest system can reach 137 dB measured at 1 meter.
LRAD systems are used by maritime, law enforcement, military and commercial security companies to send instructions and warnings over distances, and to deter aggressors. LRAD is also used to deter wildlife from airport runways, wind and solar farms, nuclear power facilities, mining and agricultural operations and other industrial facilities.
Yes, totally deaf people should not be bothered by this. Not "become immune".