This week New Zealand is having an annual civil defence emergency awareness week. Part of this was the first public test of a highly mobile warning system, designed to provide early warning of impending disaster - particularly a tsunami. The warning system bit refers to the fact that there are a couple of big speakers involved, and the highly mobile is because it is attached to a chopper.
In this case, a Helipro Aerospatiale AS 355 F1, ZK-HYN was doing the deed. Being windy it was a bit hard to hear, but it was definitely loud! Here's the best picture of a bunch of horrible picture :-)