2 Darts WHINE on Heralds, F27s and 748s, but 4 Darts SING on a Viscount or Argosy.
I spent a bit of time spannering on cargo Heralds and used to make a bed on the boxes as far back as possible to get away from the noise.
One of our captains announced one night that he had just clocked up 10,000 hours on the Herald. He was a bit deaf.