I Humming Top Acoustics: Unearthing the Mystery

[Anachronist]

TL;DR Summary

Are multiple simultaneous tones produced due to the hole spacing or because there are chambers inside?

I remember having a humming top toy when I was a small boy, and I vaguely remember it made a sound when spun.

Here's a 30-second example:
...and more examples are available on YouTube.

It's interesting to me that the sound doesn't start right away after the driving force is removed. It builds up.

More interesting to me is the production of multiple tones all at once. I found one video of a top that sounded like a perfect major chord.

All of these have a series of holes in the side. My memory is faulty in my age, but I could swear mine had two or three pairs of holes. The video above shows four holes in a row.

If there is one big hollow space inside, would the hole spacing account for the multiple tones? I'm somewhat familiar with the concept of a Helmholtz resonator, which would imply that there are different-sized chambers inside, but a Helmholtz resonator may not work well with multiple closely-spaced openings to the chamber.

Try as I might, I cannot find any explanation of what the interiors of humming tops look like, or how they are constructed. I started looking into this because I was thinking about designing a toy glider with a hollow body that whistles or hums, but I am starting to suspect that the airspeed may never be fast enough, considering the rotational speed of these tops.

 

[Baluncore]

Try google search.
http://www.waynesthisandthat.com/howmusicaltopswork.html

 

[Anachronist]

I did google searches for "humming top innards", "how humming tops work" and many other things, and I did not come across that site.

In fact, the author of that page also had my experience. He says: "... I attempted to find the answer on the Internet. For once Google let me down. No matter what combination of keywords I used I either got ads to purchase toy tops or information pages about top musical performers. I ran through the top 100 pages on several searches without finding a single page explaining how musical tops work."

That was my experience exactly. Oddly, I never came across this page. I didn't use the keyword "musical" however. I was using "humming", "whistling", "noisy", "buzzing", etc.

Thanks. That's just what I needed.

 

[Anachronist]

Oh, my. I sure was wrong. The page http://www.waynesthisandthat.com/howmusicaltopswork.html explains that these tops don't use whistles at all. This isn't a Helmholtz resonator as I initially thought. It's a harmonica! The ports on the side aren't whistles, they are exhaust ports. Air is ejected by centripetal force, and drawn in through ports at the bottom. And the sound is made by the air flowing across reeds tuned for different notes.

 

[Baluncore]

I was using "humming", "whistling", "noisy", "buzzing", etc.

I googled 'singing spinning top theory' and that was the third result.

I did not expect to find there was a 200:1 gearbox in the base.