1 That prompted the invention of the" long range acoustic device"( LRAD), designed to keep small boats away from warships.

2 And some have the long-range acoustic device, a sound cannon that can be used to issue verbal warnings, or deafen anyone who stands in its path.

3 It is shown that the transmisson-line matrix method can be applied to numerical simulation of working process of acoustic device in time domain.

4 If troops spot someone suspicious approaching them, they can use the Long Range Acoustic Device to send a warning message.

5 They should have used other means to shake off the pirates, like a loud acoustic device.