S. [x], [ɸ] vocalized between a vowel and [s], [θ]; [Vx{θs}|Vɸ{θs}] > [Vi{θs}|Vu{θs}]

S. [ɣ], [ŋ] vocalized before [l], [r], [m], [n]; [V{ɣŋ}{lrmn}] > [Vi{lrmn}]

S. voiced stops became spirants after vowels; [V{bdg}] > [V{vðɣ}]

I will start working on a new release of Atanquesta in the coming weeks. I plan to

• expand the grammar explanations and add even more examples

• rework the dual nouns section to better reflect current consensus

• add questions/exercises at the end of lessons

I don't know how long it will take, depends on my job, life etc. I will of course make an announcement when ready.

Challenge of the [day|week|month]? Devise a nice, smart idiom to say by the way in Q.

My first line of thinking is around the roots AD(A), HEK, SAT (=> "beside, aside, to the side"), but have not yet been able to come up with a nice way of using them. Of course other metaphors could work as well.

Any ideas out there?

S. short [i], [u] became [e], [o] preceding final [a]; [-{ĭŭ}{C|CC}a] > [-{eo}{C|CC}a]

In both Sindarin and Noldorin, the short vowels i and u were lowered to e and o in the syllable before final a, a phenomenon known as a-affection after the corresponding sound changes in Welsh (WGCH/§68). Tolkien himself used this term for the phenomenon:

S. initial [w] became [gw]; [w-] > [gw-]

At every conceptual stage of Sindarin (including Gnomish and Noldorin), an initial w- became gw-. An identical development took place in Welsh (WGCH/§100i). Tolkien described this change several times:

S. [zb], [zg] became [ðβ], [ðɣ]; [z{bg}] > [ð{βɣ}]

In Sindarin a [z] became [ð] before the voiced stops [b] and [g], which themselves became voiced spirants [β] and [ɣ]. This sound change is distinct from the development of [z] before [d], where the [z] vanished while lengthening preceding vowel. This sound change is discussed in notes appearing in the Outline of Phonology [OP2] from the early 1950s:

S. voiced stops became spirants after liquids; [{rl}{bdg}] > [{rl}{vðɣ}]

In Sindarin and Noldorin voiced stops became spirants after the liquids [l] and [r]; voiceless stops underwent a similar development, though the mechanism was different. These combinations went through a nearly identical development in Welsh (WGHC/§105ii). In fact, Tolkien compared Sindarin to Welsh to describe this sound change: