2851: How Long are Long Vowels? Oct 10, 2024

If you were operating a telegraph, you would need to distinguish from dots (*) and dashes (—), (and to time empty spacing) given that ambiguity in any of these lengths would lead to confusion and unintelligibility. This means that the relative length of a dot to a dash is standardly 1:3. A similar problem emerges in languages with short and long sounds.

In some languages, this is somewhat foolproof, because in some languages, vowel length for instance is interdependent with the surrounding sounds. In Swedish and pre-Modern Hebrew* for instance, a long consonant is always preceded by a short vowel and vice versa. Meanwhile, in languages like Estonian and Arabic, the length of any consonant or vowel is an independent feature for the most part.  

Languages with phonemic vowel length or consonant length most commonly see a ratio of 1:2 comparing how much time a short or long vowel is released. Some exceptions exist, like Finnish which is 1:3, so you might expect that other languages where the relative lengths of consonants and vowels are independent, to also be long. Actually in Arabic, the ratios can still be 1:2 or even closer because the average length for long vowels (for all languages, really) depends to an extend on the vowel in question with high-vowels like /i:/ usually being shorter. In Estonian too, with short, long, and overlong vowels, the ratio is somewhere like 1:2:4 or even 1:2:5.

*In Hebrew, this principle is often undermined by elision that instead forces a long consonant after a long vowel.