two pitches for five vowels

On La Gomera the valleys are barrancos — ravines cut so deep that the house you are looking at, across the gap, is a walk that would eat the better part of the day: down one wall, along the dry bed, up the other. So the man on this wall does not walk. He hooks a knuckle behind his teeth, cups his free hand to his cheek, and whistles, and the whistle crosses in the few seconds the legs would have spent the morning on. A good one reaches two kilometres, five in open mountain, and across one clear canyon on the island the measured record is ten. It is louder than a shout and far cleaner — a single pure tone up near two or three thousand hertz, in a band the wind and the running water mostly leave alone — and it travels something like ten times as far as any voice. It is not a code standing in for the language. It is the language, pushed down a narrower pipe.

The pipe holds one note at a time, and that is the whole problem and the whole art. A voice is thick: a low fundamental with a stack of resonances riding on top, and the mouth bends that stack into the difference between an ee and an oh. A whistle cannot carry a stack. So the whistler keeps a single strand of it — the second formant, the resonance the tongue tunes as it travels front to back, the one that does most of the work of telling one vowel from another — and lets the rest go. In Silbo, the island's Spanish, the five vowels collapse into two heights: i and e ride high, a and o and u sit low. The consonants are what happens between them — how far the pitch leaps to reach the next vowel, how steeply, whether the line breaks for an instant or slides on unbroken. The grain of the voice, the breath, the particular person doing the whistling: none of it crosses. What crosses is the shape the mouth was making. Only that.

It should not be enough to go on, and on its own it nearly isn't. Give a fluent islander one whistled word with no sentence around it and he names it right about seven times in ten. What saves it is that no one talks in single words. Set the same word inside an ordinary sentence and the figure climbs toward nine in ten — the gaps closed by the words on either side, by what the day has been about, by the short list of things a person on the far wall would plausibly be calling across to say. Spoken language is wildly over-built, every word carried more ways than it strictly needs; the whistle throws the surplus away and leans on the listener to have it already. It does not send the word. It sends enough of the word, to someone who shares the valley.

All of that works only because Spanish treats pitch as loose change. The voice does not use height to tell one word from another, so the whistle is free to spend height on the vowels. A tonal language has no loose change. In Mandarin, in Hmong, in Yoruba, pitch is already working — it carries the tone, and the tone is inside the word, the same syllable at a different height meaning a different thing. Now the single note has two jobs and can do exactly one. The whistler has to choose, and he chooses the tone, because letting the tone go lets the word go whole. So the tune crosses the canyon and the vowels and consonants stay behind, and what lands on the far wall is rise-and-fall with the words scooped out of it. The language survives by shrinking: whistled Mandarin and its cousins run on stock phrases, repeated, and when no stock phrase exists for a thing the whistler takes the long way round, describing a path toward a meaning he has no way to name outright.

A few tongues slip the trap. Mazatec, in the Mexican sierra, is so thick with tone that the melody alone carries nearly the whole of it, and two men can hold a real, ranging conversation in pure whistle across a hillside. But the rule under all of it is plain. Force a language through a channel that holds one thread and it has to decide what it cannot do without. Spanish surrenders the body of the voice and keeps the shape of the mouth. Mandarin keeps the music and surrenders the words.

The places that kept the whistle are the places whose ground demanded it. In Sochiapam, high in Oaxaca, the Chinantec whistle so readily that plain shouting has nearly dropped out of use, and a man known for a poor, muddy whistle can lose work over it, or be fined, the way you might be for any botched skill a job depends on. Boys court in it — among the Kickapoo a young man folds a leaf against his lips and whistles to a girl through the dark, a message her parents are not meant to be able to read. In some villages it runs as the men's register: the women understand every whistled word and do not whistle back.

And it lasts only as long as the valley still asks for it. On La Gomera the roads came, and the telephone, and the canyon stopped being the obstacle that made the whistle necessary; Silbo nearly left with the last of the old shepherds. So the island made it law. Since 1999 every child on La Gomera learns to whistle it in school, a required subject like reading, and some twenty thousand people now keep a technique older than the Spanish it carries alive on purpose. Antia got no such rescue. It is a stone village on the Greek island of Euboea, and its whistle, sfyria, older and more tightly built than most, was never written into anything. Thirty-seven people still live there. Six of them can still whistle. When the last of the six is gone, the particular sound of that valley answering itself across the rock will not be made again.

The whistle never carried the voice. It carried the part of the voice that had to reach the other wall — the climb and fall of it, the shape of the mouth, the few things a neighbour could not simply have guessed — and left the rest at home, with the body that made the sound. A man on one ridge moves his tongue, and a man on the next ridge, a kilometre off through clear air, hears a whole sentence. Most of it was never sent. He had it already.