The American Speech-Language-Hearing Association (ASHA) is deeply concerned about the risk of hearing damage from the use of Long Range Acoustic Devices (LRADs).
Originally developed for the military, LRADs have been used for communication with large crowds and to disperse them. They can emit sound at extremely high decibel levels (up to 162 dB SPL) greatly exceeding that of a jet engine and significantly surpassing the average auditory threshold of pain (approximately 130 dB SPL). That level of sound is capable of causing not only permanent hearing loss, but also migraine, vestibular, and other auditory symptoms. Moreover, children, elderly individuals, and others with pre-existing sound injuries could be at increased risk of harm.
ASHA is encouraged by reports that support safer use of LRADs by police and law enforcement agencies. One city decided to stop using the devices altogether. Another undertook developing a policy for safer practices after it was sued successfully because an individual suffered permanent hearing loss from police LRAD use.
Proponents say these devices, which have speech communication capability, are needed for purposes such as making public addresses to large or noisy crowds. Yet, the decibel level of speech presented through LRADs is unsafe, capable of causing temporary and permanent hearing loss for those in front of, behind, or on the periphery of the device. And the troubling fact remains: LRADs have been and can be easily set at extremely high decibel levels that can cause serious lasting harm.
For their own hearing protection, ASHA encourages people headed to large public gatherings of any kind to take sound-reducing ear plugs or ear muffs with the highest decibel noise reduction rating they can find.*
Also, in the event of extremely high decibel LRAD use, people should:
get behind brick or concrete walls, which are a good bet for shelter
without shelter, imagine the sound as a beam and walk perpendicularly to the direction of that beam—that is, if the LRAD is in front of you, go left or right, rather than just backing up.
*Protection tips source:
"Understanding the LRAD, the 'Sound Cannon' Police Are Using at Protests, and How to Protect Yourself From It".