So far one person suggested offline that I use a ramped tone, starting low
and going high, and another suggested a cutoff of 2000 hz.  Not bad
suggestions.

A little research showed that 10% of the US population suffers some form of
hearing loss.  That's a lot of folks!

" The disorder (high frequency hearing loss) occurs in about 25% of people
ages 65 to 75 years old and in 50% of those over age 75." webMD.com

440 HZ is middle A, sounds like a low tone to my ear, and is on the low end
of what a piezo can do.  500 - 2000 hz is probably that widest range that
you can practically play with a piezo, and stay below the 2000 hz cutoff.

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