Dog Whistles
Both kinds
In 1876 Francis Galton created an experimental device to test hearing differences between humans and animals. The device was a whistle that emitted a sound audible to dogs but imperceptible to humans.
He called it the “Galton Whistle”.
By the way, Francis Galton was also the creator of eugenics, the “racial improvement” pseudoscience that gave plausible deniability to any bigot wanting to invoke “science” to justify their racism.
So, yeah. Francis Galton invented the dog whistle. Both kinds.
