Just had a similar things today, was just driving into Sandringham estate along a private road at about 20mph and then it started squealing/squeeking as if a stone was stuck in the disk, then a slight hiss noise sporadically, it stopped squeeking but emitted random hiss noises on the way home (like a quiet version of a bus's air brakes), its not the same noise as the DV as this is a deeper hiss.
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