As a general linguistic question, what determines if something is a diphthong, or just a combination of two standalone vowels?
I’m currently studying “Finnish: An Essential Grammar” by Fred Karlsson (second edition from 1999, even though a third one is already available), and I don’t quite get it from the examples.
According to the book, in Finnish there are “16 common diphthongs.” First of all, what the hell does the author mean by “16 common” – are there any uncommon ones in addition?
Second of all, as I read and pronounce the words to myself, I don’t really perceive some of them as diphthongs (the ones that do not sound like diphthongs to me I’ll mark in red):
ei (ei, leipä, Veikko)
äi (äiti, päivä, väittää)
ai (aika, vaikka, kaikki)
oi (voin, poika, toinen)
ui (uin, kuin, puissa)
öi (söin, töissä)
yi (hyi, lyijy)
uo (tuo, juon, Puola)
yö (yö, työ, syön)
au (taulu, kaula, sauna)
ou (koulu, krouvi, noudan)
eu (reuna, seutu, Keuruu)
iu (viulu, hius, kiusaan)
äy (täynnä, käyn, näytän)
öy (köyhä, löyly, löydän)
ie (tie, mies, vien)
What do you think – are all of the abovementioned vowel combinations diphthongs or not? What is the criterion? As far as I understand it, a diphthong is a combination of vowels that do sound as one, and it would be really hard to take them apart in order to form separate vowels. However, vowel combinations like tie, yö, tuo, Puola, juon, mies, syön etc. do not sound like diphthongs to me at all. Is it because my Finnish is not good enough, or is the author wrong in his description of the language (which by the way he has been many times throughout the book)?
Also, among the examples above there are ones about which I haven’t got much of a clue if they’re diphthongs or not. I have therefore not market them in red, but that doesn’t mean that I completely perceive all unmarked words as diphthongs.
Last but not least, do you guys know a good dictionary that has voice recordings of the words – this way I could probably hear for myself, without bothering you with such a long posting