Originally, there were two kinds of l, n, r sounds: lax and tense. That is why l, n, r are written doubled ll, nn, rr: Because they were tense. This distinction between tense and lax l, n, r is almost lost in Munster Irish. They are pronounced the same. But the "tenseness" went to the vowels which became long (or they were diphthongised).
We can divide the (originally) tense consonants in groups:
1) tense l,n, r written ll, nn, rr 2) In consonant combinations as nt, rd, ns etc. the l,n,r part is (was) tense, too (though written single) 3) And m, ng are always tense (there is no "lax" variant). 4) Consonant combinations as mp, mt, nc (= ng+c)
So, all these 3 groups behave similar in lenthening or diphthongising vowels before them - as long as no other vowel follows.
If a vowel follows, vowels before 1) + 3) become short but vowels before 2) + 4) stay long.
And there is group 5): There can be consonants following ll, nn, rr (usually only verb endings in t, th, f, like -tar, -fidh, -fear, -te etc. or plural noun endings as -te, -tí). Vowels before ll, nn, rr in 5) stay long, too.
The reason is probably very simple:
Lengthening (and dipthongisation) only happens when "tense" l, n, r, m are part of the same syllable: fill, fillte, filltear, bord, barda, lampa, insint: all vowels are in the same syllable as l,n,r, m: fill, fill-te, fill-tear, bord, bar-da, lam-pa, in-sint. So, the vowels are long (or diphthongs).
But when "tense" l, n, r, m are transferred to the the next syllable they lose their lengthening effect: coille, filleadh, ama, ime, etc.: coi-lle, fi-lleadh, a-ma, i-me. Vowels are short.
|