From the last 3 RBA meetings (June, July & August) the decision to increase interest rates by 50bps resulted in a drop in AUDUSD (typically an interest rate hike should see the currency appreciate)
This move is likely due to the effect of a priced-in scenario where the decision had been signaled by the RBA and much anticipated by the market.
With the upcoming interest rate decision expected to present a 50bps rate hike again, the AUDUSD could reject the 0.6845 resistance level to trade lower towards the 0.6760 support level.