Fran,
To hear the choo-choo, go to www.youtube.com. Type in "American Flyer Choo Choo." Several videos will come on screen. Click on one or two and you will hear the Choo Choo sound.
American Flyer used a small leather bellows (like a tiny accordion) to make the Choo Choo sound. But as the bellows wore, they cracked and leaked. Then each bellows wa replaced with a metal piston. The airflow also pushed smoke out the stack synchronized with the Choo Choo. The closest I can come to describing it in print is to say that it works like a small air pump, and it has a fssh-fssh sound emitted by manual tire pumps. Enclosed by a boiler casting (or a tender body for Smoke-in-Tender locomotives in the late 1940's), the Choo Choo sounds pretty good, in my opinion. Some American Flyer steamers had Choo Choo but not Smoke; others had neither.
American Flyer introduced electronic horns and whistles and "diesel roar" in the 1950's, as well as DC operation. But technology couldn't reproduce realistic sounds. It took a good 45 years for printed circuit boards and hi-tech to accomplish AF's goals.
