Q. initial [ps], [ks] became [ups], [iks]; [ps-|ks-] > [ups-|iks-]

Late in Tarquesta [TQ] the initial combinations ps-, ks- came to be pronounced ups-, iks-, a sound change described in both the Outline of Phonetic Development [OP1] from the 1930s and the Outline of Phonology [OP2] from the 1950s:

Q. initial [ŋ] became [n]; [ŋ-] > [n-]

In Tarquesta [TQ] pronunciation an initial velar nasal ñ [ŋ] was often pronounced as a dental nasal n, especially among the Vanyar. This sound change was not reflected in spelling. Tolkien mentioned this phonetic development in both the Outline of Phonetic Development [OP1] from the 1930s and the Outline of Phonology [OP2] from the 1950s:

Q. [rs] became [ss]; [rs] > [ss]

In Tarquesta [TQ] pronunciation there was a tendency to unvoice r before s and simplify the pair to ss. Supposedly this effected r of all origins, and also s < þ. Tolkien mentioned this phonetic development in both the Outline of Phonetic Development [OP1] from the 1930s and the Outline of Phonology [OP2] from the 1950s:

Ké lamyas *úsávima, mal *autamor akárier terkénima kauma ya pole fanta  engwi kata sa (lan apantas i *katamen) ar vista te lakénime - laqui nante ambena i kauma, itas eke mon hententa te...

Maybe it sounds hard to believe, but inventors have made a transparent shield which is able to veil things behind it (while showing the background) and turn them invisible - unless they are closer to the shield, in which case one can spot them...

Q. [z] became [r]; [z] > [r]

Q. [d] vanished between [n], [r], [l] and [j]; [Vð{Vw}] > [Vr{Vw}]

Q. [d] vanished between [n], [r], [l] and [j]; [{nrl}dj] > [{nrl}øj]

In Ñoldorin Tarquesta [TQ], the d vanished in the combinations ndy, ldy, rdy, resulting in ny, ly, ry in that dialect. When Tolkien first mentioned these combinations in the Outline of Phonetic Development [OP1] from the 1930s, he described only the Lindarin [pre-Vanyarin] phonetic developments, where he first had [ndj, ldj, rdj] develop into [ndʒ, ldʒ, rdʒ]:

Q. [sp], [sk] became [ps], [sk]; [sp|sk|skw] > [ps|ks|skw]

In Quenya the combinations sp, sk were frequently transposed to ps, ks: universally in the case of medial ps, sporadically in other cases. This sound change happened both initially and medially, and the initial transpositions introduced the new initial clusters ps-, ks- to Quenya. Although established in Early Qenya, the frequency and nature of these sound changes evolved over Tolkien’s life.

Q. [θ] became [s]; [θ] > [s]

Q. final consonants became dentals; [-{pk}|-{mŋ}] > [-t|-n]