That's very, very different from whistled languages. In Silbo Gomero, one of the main examples here, there's a whistled equivalent to each sound in Spanish. T

That's very, very different from whistled languages. In Silbo Gomero, one of the main examples here, there's a whistled equivalent to each sound in Spanish. The difference is approximately as far as waving-hands-to-indicate-something vs. full-on sign language (though sign-languages are genuinely separate languages, whereas this is just a different register of an existing language). As it were, I've actually spent around a year on the small island of La Gomera, where Silbo Gomero comes from. All kids have it in school as an attempt to preserve it.