sound weapons were rumoured to be at the protest site; this appears to provide the evidence:
13 Feb: Youtube: 4m03s: Police deploy Sonic weapons against Women and Children at Parliament House! SHAME!
posted by Aussie Cossack
(Prime Minister) Scott Morrison continues to commit crimes against the Australian people deploying Sonic low frequency weapons against peaceful protesters! Shame on you SCOMO!
https://www.youtube.com/watch?v=nXs9s45dQXM
That’s at the protest in Australia’s capital Canberra.
What are sound/sonic weapons?