Here is a copy of a full page advertisement placed by the Southern Railway in the Washington Times Herald in 1951. Early diesel locomotives came equipped with single note “goose” horns that sounded nothing like the melodious steam whistles people had grown up with. This advertisement is an example of how railroads at that time were so image conscious that many of them really “gave a hoot about the toot.” As a result they bought newly designed air chime horns that sounded like steam whistles.
I have two Nathan M5’s in my collection. They are physically the same except one is painted silver and the second is painted black.
Silver M5 Recording:
Black M5 Recording: