what is a vowel?

[skothari01]

i mean, in general.

are vowels distinguished from consonants on purely acoustic (phonetic?) grounds? i think this would imply that the same sounds would be considered vowels in any language. or, instead of the intrinsic acoustic properties of the sound, is it a function of how those sounds are articulated physiologically (realizing, of course, that there could be a close connection between the manner of articulation & the nature of the sound that results)? or, rather than the sound itself, is it the role that the sound plays in the structure of a particular language (phonology?), implying that the same sound may be a vowel in one language and not another (?). are there many more vowels possible than we are familiar with in indo-european languages? for that matter, do all languages have vowels (is it a linguistic universal)?

i am sorry if all of this seems too far afield. it all started with my trying to understand the discussion of consonantal vowels and (especially) sonant vowels in my beginning greek textbook (in order to better understand & learn my third declension paradigms). i realized that, despite my clear intuitions (implicit knowledge) about what vowels were and an ability to use them successfully in speaking my native tongue, i really couldn't describe them explicitly (as opposed to 'pointing' to certain sounds as examples).

i will try to look this up in a good linguistics textbook (any suggestions?).

[aso]

the short answer, i think, is that a vowel is a sound that you can vocalize continuously. for example, i can say "aaaaaaaaaaa" but i'd have a hard time saying "pppppppppppppppp."

there are lots of complications, though. certain consonants (glides or semivowels, nasals, approximants, etc) meet the "continuous vocalization" test, but aren't considered vowels. i can say "mmmmm" but i learned in elementary school that english contains five vowels: a, e, i, o, u, and sometimes y (which is really a mindjob, now that i think about it). the reason that "m" is considered a consonant in english is because it is rarely used syllabically. there's another criterion:

a vowel is a sound that can form a syllable.

in english, the sound "m" rarely forms a syllable by itself. instead, it either opens a syllable ("ma") or closes one ("am") or both ("mam"). the syllabicity of nasals in proto-indo-european leads to divergences in the declensions of the greek noun. the PIE accusative singular ends in "m," whether or not the stem ends in a vowel. so for a stem like "theo" (to take a simplified example), the ending "-m" results in the accusative "theon." for a stem like "phylak" (again, simplified), the ending "-m" is syllabic and is realized in greek as the short vowel "a," hence "phylaka."

so, you can see, the lines are blurry. in english, we don't consider "l" and "r" vowels, and this is reflected in our orthography, but we do pronounce "little," for example, with something like a syllabic "l."

[modus.irrealis]

Just to add to aso's answer, I'd say that the word vowel is used for both ideas. You do come across definitions of vowels that are purely acoustic (or physiological), but it's also used for anything that forms the nucleus of a syllable. E.g. Sanskrit is often said to have vowels r and l.

As for whether vowels are universal, I've read that they are and I believe that all languages have a minimum of 3 vowels. This is mentioned here.

About vowels outside Indo-European languages, that's an interesting question, but I'm not familiar enough with IE languages to know which vowels occur in them, but you can find vowels like unrounded u in Turkish or unrounded o in Mandarin. I don't know if either of these exist in any IE languages.

But a good textbook to read for this is anything by Peter Ladefoged. Vowels and Consonants is really good and sound samples from the book are available online.

[edonnelly]

I think people who do voice-recognition and neural-network processing of speech use the International Phonetic Association which has a Vowel Classification Scheme and an International Phonetic Alphabet. Unfortunately, I'm not familiar enough with it to know exactly how they distinguish a vowel from a consonant, but I'm sure their website has some good (and fairly scientific) information, if you're interested in looking through it.

[spiphany]

I'm not sure even linguists are always entirely sure what distinguishes a consonant from a vowel. As an example: several diphthongs in English have alternate phonetic transcriptions; one transcription version writes them as vowel + a vowel, while the other as a vowel + a glide/semivowel (English y or w sound).

The way the books I've seen define it is that a vowel is uttered with an open, resonating vocal tract, while a consonant involves complete or partial obstruction of the airflow (you see this most clearly with the stops p/b, t/d, k/g). Obviously, that's a fairly basic -- and incomplete -- definition, as it doesn't resolve the problems you bring up. But it's a start.