The dj's on KUPL (Portland, OR) were talking about this on my way to work this morning. I didn't realize they were talking about Cheeze-It and wine combo pack. Now I know, thank you John!
According to Wikipedia: Two hums have been linked to mechanical sources. The West Seattle Hum was traced to a vacuum pump used by CalPortland to offload cargo from ships. After CalPortland replaced the silencers on the machine, reports of the hum ceased.[22] Likewise, the Wellington Hum is thought to have been due to the diesel generator on a visiting ship.[23][24] A 35 Hz hum in Windsor, Ontario, is likely to have originated from a steelworks on the industrial zone of Zug Island near Detroit.[25]I wonder if they've looked into those possibilities. I remember hearing about the Seattle Hum. Researchers thought maybe it was due to the mating calls of midshipmen fish before tracing it to the vacuum pump.
That's cool! Back when I was a kid, we had a bookmobile that would come in to our very rural school at least once a month. The bookmobile was turned into a stationary library on school property. It served the community for years until a library was built just down the road from the school.