Hi Tom,
The 30" gauge VFCO out of Sao Jao del Rei in Brazil used tall single chime whistles which the engineers could overblow at will. They could hoot and screech at will. I've got super 8 sound movies that I took back in 1982, but nothing that I can post. We were lucky, the line closed a month after we were there and was then cut back to a 12km long tourist line. At least it's still there and all the locos survived. Neat line, used 4-4-0's, 4-6-0's and 2-8-0's.
Richard Carter had a huge collection of whistles when he worked at Cass. He took a bunch of his whistles up the mountain one day for a whistle blow for Semaphore Records. I don't think the session was ever released, but he had a Southern top lever "boot leg" single chime hooter that he could make hoot or screech as well. It was a cloudy day and very humid and the echo's were fantastic. I timed the last echo from the bootleg and it took 19 seconds for the last echo to come back.
Michael Allen