Why living in the mountains affects the way you speak: Thinner air makes it easier to say certain sounds

Where we live - specifically, how high up we live - may have a far bigger impact on how languages are formed than previously thought.

Languages containing 'ejective' consonants - guttural bursts of sound not found in English - mainly exist among communities at high altitudes.

Lead scientist Dr Caleb Everett from the University of Miami believes that the reason might be that it takes less effort to produce ejectives in thinner mountain air.

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On this partial world map, dark circles represent the areas where languages where ejectives occur. Clear circles represent areas where the ejective isn't part of the language. Scientists found a correlation between ejective languages and high altitude.

Until recently most linguists believed environment mainly had an influence on vocabulary rather than sound.

Researchers in the US found that 87 per cent of the languages with ejectives studied were located within 500 kilometres of a region of high elevation on all continents.

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As the height of the land increased, so did the likelihood of there being languages with ejectives.

'This is really strong evidence that geography does influence phonology - the sound system of languages,' said lead scientist Dr Caleb Everett, from the University of Miami.

An area of high elevation is defined as having an altitude higher than 1,500 metres above sea level.

Inhabitants of Peru, like this family on Lake Titcaca, have a ejective-heavy language

Most of the inhabitable high altitude areas of the world are found in six regions, including the North American Cordillera, the Andes and the Andean altiplano, the southern African plateau, the east African rift plateau, the Ethiopian highlands, the Caucasus range, the Javakheti plateau, and the Tibetan plateau.

HOW TO  MAKE  AN EJECTIVE CONSONANT

1. Start by holding your breath

2. While you're still holding your breath, try to make a 'k' sound

3. Make the sound as loudly as you can, so that somebody sitting next to you can hear it

4. Relax and breathe in again

5. You've just made an ejective k

The researchers, whose findings appear in the online journal Public Library of Science ONE, looked at the locations of around 600 representative languages, 92 of which had ejectives.

A computer program was used to match linguistic sounds to particular geographical locations.

The results showed a strong correlation between elevation and ejective languages on, or near, five of the six major inhabited high altitude regions on Earth.

'Ejectives are produced by creating a pocket of air in the pharynx then compressing it,' said Dr Everett.

'Since air pressure decreases with altitude and it takes less effort to compress less dense air, I speculate that it's easier to produce these sounds at high altitude.'

The only high altitude region where ejective languages were absent was the large Tibetan plateau and adjacent areas.

This could be because people living in this region are uniquely adapted to high altitude conditions, the scientists believe.

Studies have shown that Tibetan people breath at a faster rate than other high altitude populations, which reduces the effects of reduced oxygen.