S. final [ɣ] became [a] after a consonant; [-Cɣ|-Cɣi] > [-Ca|-Cī]

S. final [ɣ] became [a] after a consonant; [-Cɣ|-Cɣi] > [-Ca|-Cī]

In both Sindarin and Noldorin, if a post-consonantal voiced spirant [ɣ] became final after vowels vanished at the end of words, then [ɣ] developed into the vowel [a]. This sound change was noted by David Salo in Gateway to Sindarin (GS/§4.155). Tolkien himself more fully described this phonetic development in notes written in the 1950s:

In Sindarin zd > ´d, đ but zg, zb > đʒ, đƀ > đa, đu, as in nadha “fetter” [< ✶nazg-], maða “mud” [< ✶mazgō/ŭ], buðu “large fly” [< ✶buzbō] (PE19/101). [The primitive forms appear earlier on the same page in Quenya derivations.]

This note only mentions this phonetic development in the case when [g] became a spirant after [ð], but the same seems to be true after voiced stops became spirants after liquids [l] and [r]:

The phonetic development is a bit different in case of plural forms. The plural of N. fela “cave” is fili (Ety/PHÉLEG) which indicates that [-Cɣi] > [-Cɣʲ] > [-Ci]: *phelgi > *filʒi > *filʒʲ > fili. This only makes sense if [-Cɣʲ] > [-Ci] after final vowel losses, which explains why the final [i] survived. See the entry on how final [i], [u] generally vanished.

The note from PE19/101 above hints at similar vocalizations for [β] or [v] after [ð], but the details of this phonetic development differ: see the entry on how [ðv] became [ðw] for further discussion.

Conceptual Developments: There doesn’t seem to be any clear evidence of this phonetic development one way or another in the Gnomish words of the 1910s, but there are several examples of this sound change in the Early Noldorin word lists of the 1920s, as noted by Roman Rausch in his Historical Phonologies of Ilkorin, Telerin and Noldorin around 1923 (HPITN/§4.1.4):

At this earlier conceptual stage, however, it seems [-Cɣi] > [-Cy] instead of [-Ci] based on the plural forms above.

Reference ✧ PE19/101 ✧ final [ɣ], [v] became [a], [u] after a consonant for example: nadha < ✶nazg-, maða < ✶mazgō/ŭ, buðu < ✶buzbō

Order (02800)

After 00600 [zb], [zg] became [ðβ], [ðɣ] ✶buzbō > S. buðu
✶nazg- > S. nadha		 PE19/101
PE19/101
After 02300 short final vowels vanished ✶buzbō > S. buðu
✶phelgā > S. fela		 PE19/101
PE17/118
Before 03000 [ɣ] otherwise vanished ✶phelgā > S. fela
✶mazgō/ŭ > S. maða		 PE17/118
PE19/101
Before 06200 non-initial [m] usually became [v] ✶julmā > S. ylf WJ/416

Phonetic Rule Elements

[-Cɣ] > [-Ca] ✧ PE19/101 (đʒ > đa)
[-Cɣi] > [-Cī]

Phonetic Rule Examples

felɣ > fela -Cɣ > -Ca ✶phelga > S. fela ✧ NM/304
felɣ > fela -Cɣ > -Ca ✶phelgā > S. fela ✧ PE17/118
maðɣ > maða -Cɣ > -Ca ✶mazgō/ŭ > S. maða ✧ PE19/101
naðɣ > naða -Cɣ > -Ca ✶nazg- > S. nadha ✧ PE19/101
filɣi > filī -Cɣi > -Cī ✶phelgai > felʒi > S. fili ✧ NM/304

N. final [ɣ] became [a] after a consonant; [-C{vɣ}|-Cɣi] > [-C{ua}|-Cī]

GS/§4.51 GS/§4.155 GS/§4.156 WGHC/§110ii-2 (-ɣ > -y > -a); sometimes [-lu] < [-lv]: N. galw @@@

Order (02600)

After 02100 short final vowels vanished ᴹ√MÁSAG > madhgh > N. mada
ON. phelga > N. fela		 EtyAC/MASAG
Ety/PHÉLEG
Before 02800 [ɣ] otherwise vanished ᴹ√MÁSAG > madhgh > N. mada
ON. phelga > N. fela		 EtyAC/MASAG
Ety/PHÉLEG

Phonetic Rule Elements

[-Cɣ] > [-Ca]
[-Cɣi] > [-Cī]

Phonetic Rule Examples

felɣ > fela -Cɣ > -Ca ON. phelga > N. fela ✧ Ety/PHÉLEG
maðɣ > maða -Cɣ > -Ca ᴹ√MÁSAG > madhgh > N. mada ✧ EtyAC/MASAG
tarɣ > tara -Cɣ > -Ca ON. targa > N. tara ✧ Ety/TÁRAG
tarɣ > tara -Cɣ > -Ca ON. targa > targh > N. tara ✧ PE22/34
θalɣ > θala -Cɣ > -Ca ON. sthalga > N. thala ✧ Ety/STÁLAG
θelɣ > θela -Cɣ > -Ca ᴹ√STELEG > N. thela ✧ Ety/STELEG
filɣi > filī -Cɣi > -Cī ON. phelga > N. fili ✧ Ety/PHÉLEG