Vancouver police Const. Lindsay Houghton holds up the department's medium-range acoustic device. (CBC)

Vancouver police say they have disabled the ability of a new piece of equipment so it can no longer be used as an acoustic weapon.

The police faced criticism from the BC Civil Liberties Association for the purchase of the long-range acoustic device, or LRAD, which was originally developed for the U.S. military.

The device can be used either as an extremely loud hailing device to warn off attackers or intruders or to emit piercing sounds loud enough to damage human hearing in order to drive people away.

'The tone capability of our LRAD will be disabled.'—Const. Lindsay Houghton, Vancouver police

Const. Lindsay Houghton said police always intended to use the device as a loudspeaker and not a weapon, but that function will be disabled, for now.

"The tone capability of our LRAD will be disabled, and if there are any alternate uses for the device in the future, other than a public address system, we would certainly develop appropriate policy and training, and that would go before the Vancouver police board for approval," said Houghton.

The BC Civil Liberties Association, which initially revealed that police purchased the device and raised concerns it might be used on protesters during the 2010 Olympics, said it welcomed the announcement.

The type of LRAD purchased by the Vancouver Police Department is a compact version designed for mounting on vehicles and is also called a medium-range acoustic device.