Train Whistles - John Dunn, Consultant, Ambertec, P.E., P.C.

I was listening to an interview on Public Radio earlier today where the topic was acoustic environments,

In the course of that dialog, a comment about train whistles was offered which I have not been able to independently confirm, but which very much caught my attention.

The interviewee stated that Canadian train whistles are required by law to be triple-toned as an E-flat minor triad. American train whistles can be single-toned, but Canadian whistles must meet the more demanding requirement.  

I just had to check this out.