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.  

 

In a minor key, the "Mi" of the customary Do-Re-Mi-Fa-Sol-La-Ti-Do scale is lowered a half-tone down to "Mi-flat". Therefore, for the required triad with E-flat as "Do", we find that "Mi-flat" is G-flat and that "Sol" is B-flat.

At the piano keyboard, I played that chord, E-flat and G-flat and B-flat and guess what?? It really did sound like a train whistle.

Comments

[Rachael]

Thanks for the tip. I will definately use that in some of my (bad) music composition.

[Stoney McMurray]

Try augmenting the Bb to Bb# -- OK: B, which is more classic train-whistle. But why do the Canadians specify the key? It would be interesting to know whether this was based on some study of human perception of train whistles, or just some arbitrary bit of bureaucratic over-reach. Certainly, the augmented triad is meant to be more jarring than a plain minor triad would be, and thus more attention-getting for anybody with an ear trained even minimally to Western music.

[William Ketel]

The whistles that we made in the shop to simulate a train whistle, which they did fairly well, used tubes that were 4,5,6,and 7 inches long. With the plugs taking up about 1 inch total, it was an interesting way to provide uniformity without needing any complex instrumentation. And they all did sound pretty much the same. It was a good use for scraps of hydraulic tubing.

[John Dunn]

From the group Technology Professionals of New York and New Jersey:

C.K. Leverett, PMP • John, I sent your link off to a group of railroad friends, including a couple of Canadians, and got this response back from one of them:

"The reason Canadian horns must be three tone goes back to the initial introduction of the EMD F-units in the 40's. The single tone (blat) horn was close to a moose mating call, and attracted them to the tracks where many were killed by trains."

So now we know the rest of the story.

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Thank you, C.K. Leverett.