In both Sindarin and Noldorin, wherever the vowel [œ] arose as the result of i-affection, it eventually developed into [e]. The clearest description of this sound change appears in Tolkien’s notes on the Noldorin use of the Feanorian Alphabet from the 1930s, where he mentioned this sound change several times:

• Later [œ̆], [œ̆ı̯] became [e], [eı], while the quantity of vowels was largely regulated by stress and the following consonant (PE22/37).
• [œ̆]* affection of ŏ; hG hÖ h|; h| [later] > [e], q.v. (PE22/38).
• [œ̆]* This was never long. In final stressed syllables — where short vowels were lengthened — it did not occur, since here affection of o was > y. It occurred before ON ya as orya; but here œı developed: œır > eır (PE22/38).
• [œ̆ı̯] affected ŏ, ŭ in unstressed syllables + epenthetic ı̯. hÖ| œi later > ei, and so to [e] or [e͡i] (PE22/39).

As the notes above indicate, in Noldorin wherever the diphthong [œi] arose from i-intrusion, it too became [ei]. The phonetic development of the diphthong [œi] is much less clear in Sindarin, since it arose only rarely: see the entry on how [œi] became [ui] or [y] for further discussion.

Some clear examples of this change include:

• Archaic S. and N. †arnoediad “unnumbered” vs. later arnediad (S/192; WJ/28; Ety/NOT).
• Archaic S. †Goelydh plural of Golodh “Noldo” vs. later Gelydh (WJ/364; S/238), in Noldorin gœlœidh vs. later geleidh (PE22/41; Ety/ÑGOLOD).

Analyzing the intermediate developments is complicated by the fact that Tolkien sometimes wrote oe for [œ], which he also used to represent the diphthong [oe]. In other cases, Tolkien did write œ, but it was recorded as oe when published. And sometimes Tolkien’s handwriting is simply hard to decipher for such subtle distinctions.

Conceptual Developments: I-affection was not a factor in the earliest Gnomish plurals. As noted in Thorsten Renk’s Early Noldorin Plural Patterns (ENPP), the vowel o in the initial syllable of words became either oe or e for plurals in Early Noldorin, though in one exceptional case it became y: ᴱN. lylyth plural of ᴱN. loloth “poplar-tree” (PE13/149). Thus it seems likely that [œ] > [e] was introduced soon after i-affection. In fact, there is one example in the early Noldorin Dictionary where ᴱN. goelydh appears before gelydh as an (older?) plural of ᴱN. Golodh “Gnome” (PE13/162). Roman Rausch also noted this as the probable development in his Historical Phonologies of Ilkorin, Telerin and Noldorin around 1923 (HPITN/§4.2.1).

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