To Hawaiian speakers, vowels reign supreme. Only eight consonants exist in the language’s 13-letter alphabet, so most of its meaning is derived from oohs and aahs, ohs and eehs. One might say Hawaiian sounds a lot like the sea that surrounds it; the bulk of its words are simple and spare, flowing smoothly from vowel to vowel. Mahalo.
On the opposite end of the spectrum, we have German. With its 30-letter alphabet, clipped consonants, and “uvulars”—sounds made by constricting the tongue against the back wall of the throat—German is famously harsh and guttural. Auf Wiedersehen! One might say—if one weren’t German, that is—that the language is cold and craggy, just like the country.
What accounts for how discrepant these languages sound? Ian Maddieson, a linguist at the University of New Mexico, had a hunch that the differences were not purely coincidental. He and a colleague, Christophe Coupe, analyzed more than 600 regional dialects around the world by topography, weather, and climate. Their findings, presented last November at the 170th Meeting of the Acoustical Society of America (ASA), claimed that the variations among the dialects exhibited a phenomenon previously only seen in birdcalls and other animal noises—acoustic adaptation. Put simply, acoustic adaptation maintains that the land where a language is born is also instrumental to how it evolves.
“Human languages must also be shaped by the evolutionary pressures that impact the behavior of all living creatures,” the authors write. “Over time, the vocabulary will begin to be shaped to suit the environment where the language is spoken.”
Maddieson targeted his research by studying how various environments affect the lifespans of various sounds. All acoustic signals degrade naturally as they move from their source because numerous factors affect their rate of decay, like temperature, humidity, and vegetation.
Not all sounds are created equal—higher-frequency signals degrade faster because they’re more attenuated by obstacles. And certain environments heighten these differences—areas with trees prevent the easy transmission of sound, and heat and humidity cause temperature ripples that chop them up. And since consonants are higher in both frequency and amplitude (they involve rapid changes in pitch and rhythm), they degrade faster, especially in hot, forested areas. Vowels, on the other hand, can slip through trees and surf heat ripples without losing too much quality, thanks to their longer and consequently sturdier wavelengths. In colder climates, consonants fare better; and at short distances, their higher frequencies don’t have the time to degrade.
As a result, “the number of distinct consonants and their deployment in syllabic structures are lower where tree cover and temperature are higher,” write Maddieson and Coupe.
This explains the vast differences between how Hawaiians and Germans speak. Just as birds in hotter and lusher regions have evolved to communicate through low coos, so languages from warm and forested regions have fewer distinct consonants and rely more heavily on vowels, as can be seen from a sampling of Hawaiian words: lapa-au, kahine, alaea. In contrast, languages from cooler, less tree-heavy climates rely more on consonants, “Wie heißt das auf?” (How do you say this?)
Acoustic adaptation may affect regional dialects, too. For example, Jackson, Mississippi, is located in the humid subtropical climate zone, with a mean annual high temperature is 65 degrees Fahrenheit; Boston’s clime is maritime and continental, and with an average yearly high of 51 degrees Fahrenheit. When folks speak in muggy Jackson, where the heat waves interfere with sound, they tend to drawl out vowels like when saying “this” (thee-is). In cooler Boston, without the rippling heat, the locals “pahk the cah in hahvahd yahd,” keeping vowels nearly constant and employ consonant variation.
The Hawaiian word “kaona” refers to hidden meanings—when something simple contains complex meaning (an example in Hawaiian is ho’omau, a single word of encouragement that implies many other motivational phrases.) Acoustic adaptation may explain why Hawaiian, to a foreigner, is heavy on kaona.
Speakers of languages from cooler climes are primed to extract meaning from consonants. If they take the time to learn the Hawaiian language, they’ll likely find it hard to detect much of the meaning contained within its vowels, which take on the intricacy and brevity of consonants in “cooler” languages. This is why, to a Hawaiian speaker, Mahalo sounds more direct than it does to other language speakers, while most German words might sound like a bunch of consonants chopping vowels into a chilly, meaningless mishmash. And why, to a German speaker, a tender Auf Wiedersehen runs over the eardrums like honey.
Susie Neilson is an editorial fellow at Nautilus. Follow her on Twitter @schmeilson.