Did the Serbian government use a sound weapon on demonstrators?

In Belgrade, a massive demonstration against President Aleksandar Vu?i? brought together between 100,000 and 300,000 people. Opposition groups and human rights activists accuse the security forces of using a banned acoustic weapon capable of causing earache, disorientation and panic. They plan to lodge a complaint with the European Court of Human Rights. The government denies the use of such a device, but does not deny possessing one. V