When i was flying large turbine powered aircraft there were a couple of things we could do to correct a poorly planned descent or a high approach.
one would be lowering the gear early... sometimes several miles out from the airport.
this would increase the drag and allow the speed to decrease into flap operating range thereby allowing us to quickly configure the aircraft for a much steeper descent and lose altitude quickly.
I would assume this would be the case in your scenario.
another thing we could do would be to push the prop levers forward bringing them to their lowest pitch setting while placing the power levers at flight idle.
this would also create an enormous amount of drag and quickly slow the aircraft. if the aircraft sounded louder than you are used to this may have been one of the techniques they were using.
I have had to do these things numerous times either due to an ATC issued altitude restriction that required a last minute crash dive so to speak or due to traffic restricting our descent capabilities or simply because of poor planning on the approach etc.
EDIT:
if the gear were down the entire time you saw the aircraft it is another possibility - however remote - that the aircraft was a non-revenue maintenance ferry flight during which the landing gear were pinned down. though i doubt this.
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