Again, it depends on what is whistling. The sound-play words are intensifiers, not valences.
- 01.092 like the whistle of an engine coming out of a tunnel.
- 02.002 Bilbo began to whistle loudly
- 05.112 a whistling
- 05.143 Whistles blew,
- 07.030 and when I call or whistle begin to come after me –
- 07.051 So Gandalf gave a long shrill whistle,
- 07.061 They don’t seem all to have come when I whistled.
- 07.062 Go on, whistle again!
- 07.063 Gandalf whistled again;
- 07.100 its whistling voices were released.
- 12.022 in fierce whistling steam,
- 14.040 Above the borders of the Forest there was whistling,
- 17.039 and arrows whistled;
“whistle, v.” OED Online. Oxford University Press, March 2015. Web. 29 May 2015.