I've been interested in whistled languages for a while now; replacing the voiced sounds of speech with whistled sounds seems like it would be really fun to hear. It's a phenomenon which has cropped up in languages across the world, mostly in isolated, rugged terrain, and most frequently among tonal languages.
Silbo Gomero has the best known whistled language, which was adapted from the indigenous language into Spanish. And who wouldn't like to visit the Canary Islands? Whistled languages are fairly common in West Africa, especially among the tonal Niger-Congo languages. Busuu.com has a couple of interesting videos demonstrating the whistling of the silbadores. They use fingered whistling, which is very loud. But it consequently seems like they map spoken phonemes to whistled phonemes that are different. It seems like whistled languages are more common in languages with a fairly small set of sounds.
Whistling is an interesting skill. Some vaudeville performers integrated whistling into their acts, usually as a novelty activity; several were able to whistle tunes with a variety of objects such as spoons in their mouths. Apparently, some people can whistle and hum at the same time, or whistle two tunes at once, or all sorts of strange things. Whistling has fallen out of favor as a musical enterprise, though. In elementary school, I whistled several tunes at my elementary school talent show.
I only have one or two memories of learning to whistle when I was a kid. I remember trying to pucker whistle in the passenger's seat of my Dad's old brown VW pickup in Oklahoma, some 20 years ago, when I got my first whistling sound. I never learned to finger whistle, because while it seemed usefully loud, I could already pucker whistle so much more fluently.
This NPR story, Whistling to Communicate in Alaska, is what really sparked my interest in whistled language. One of the Yupik girls interviewed whistles an English sentence, which was mostly readily intelligible to me, although she said whistling English was "difficult." It's been a little hard to figure out how to do this, though, because people can whistle in different ways and audio-only recordings aren't very instructive. I can only do pucker whistling, and since your lips are busy making the whistling sound, they can't make the consonant sounds of speech. English doesn't reliably distinguish vowels based on tone only: There's a limit to what Harpo Marx can communicate using only a slide whistle or a bulb horn.
At some point, I got the idea that whistled language like the Yupik girls were using was palatal whistling. I had never heard of such a thing: in the world of my childhood, you could whistle with your fingers, or you could whistle like how they explained it in that clip from "To Have and Have Not."
Trying to figure out palatal whistling, I found the Web site of whistling virtuoso and professor Tamas Hacki, which is both amazing and enormously helpful. He has recordings of whistled classical music on his site, but more helpfully, there are a number of YouTube videos of him performing. Apparently, he's been doing this since the 1960s.
It seems that the way to start to learn to do this is to make a "sh, sh, sh" noise until you get some whistle harmonics, and improve on that sound. The first few times I tried doing this for 10 minutes or so, the hyperventilating made me light-headed, so I only practiced it very rarely. In the last month or so, I've taken to attempting this on my 10-minute bicycle ride to work every day. It's a convenient block of time that I use for little except trying to avoid getting hit by cars.
Progress has been slow. At first, I was only shushing, with some rare, weak whistle harmonics here and there. Shushing a tune helped sometimes, but mostly because it forced a variety of changes in position of various parts of the mouth. About two weeks ago, I started to reliably be able to produce a whistle tone, although I can't vary it much without losing the whistle. Trying to memorize the position of my tongue when I successfully whistle this way has helped. Now, I can generally produce a whistle tone without many misfires, although I cannot control it well yet. Certainly I am not ready to join the International Artwhistling Philharmonic Society.
It's hard to describe, but it feels like my tongue is pressed against the rear of the roof of my mouth. It has a slightly rolled shape, presumably with a small opening for air at the front. Usually, my lips have a somewhat narrow rounded shape.
If I had to do this over, I'd learn Morse code at the same time, because it would give you something more interesting to do while you practice one note over and over.