Q. [ae], [ao] generally became [ē], [ō]; [ae|ao|ā{ĕŏ}] > [ē|ō|ā]

Q. [ae], [ao] generally became [ē], [ō]; [ae|ao|ā{ĕŏ}] > [ē|ō|ā]

Quenya did not tolerate the vowel combinations [ae] or [ao], and these generally became [ē] or [ō]. These sound changes explain the somewhat peculiar rule that the genitive form of nouns ending in -a was -o, for example:

This is because -aō > > -o. Tolkien discussed these phonetic developments in the Outline of Phonetic Development [OP1] from the 1930s:

In case of ae, ao contraction occurred: quality depending on length. ā + ĕ, ā + ŏ > ā; ā + ē, ă + ē̆ > ē; ā + ō, ă + ō̆ > ō (PE19/63).

Thus, ae, ao > ē, ō unless (a) the ā was long and (b) the ĕ, ŏ was short, in which case: āĕ, āŏ > ā. This sound change took place after [ɣ] from [g] vanished (PE19/63) and thus applied to all cases where a was or came to be in hiatus with e/o.

Conceptual Development: Tolkien described a similar set of sound changes in the Qenyaqesta of the 1910s:

ā̆ē̆ gave ā (aḗ); ... ăō gave ō; ā̆ŏ gave ā (PE12/14).

At this earlier stage, the default was ae, ao > ā with the exceptions ăō > o and apparently ăḗ > ăḗ. However, the only clear example of this sound change in the 1910s shows ăŏ > o (with presumably long ō > ŏ before the consonant cluster):

Thus, Tolkien may have flipped the default developments for ao early on. In the 1930s Tolkien first wrote: “Also ae > ā, ao > ō” (PE19/63 note #165) before deleting this and replacing it with the rules given above. Thus in the first draft of OP1 the combination ae still showed the Early Qenya development to ā before Tolkien revised this development to ē. There are no published examples of Quenya words containing ae at any conceptual stage, so analyzing Tolkien’s thoughts on this combination is difficult.

Order (01200)

After 01100 [ɣ] from [g] vanished
Before 02100 long final vowels were shortened

Phonetic Rule Elements

[ae] > [ē]
[ao] > [ō]
[āĕ] > [ā]
[āŏ] > [ā]

ᴹQ. [ae], [ao] generally became [ē], [ō]; [ae|ao|ā{ĕŏ}] > [ē|ō|ā]

Reference ✧ PE19/63

Order (01100)

After 01000 [ɣ] from [g] vanished
Before 02000 long final vowels were shortened

Phonetic Rule Elements

[ae] > [ē]
[ao] > [ō]
[āĕ] > [ā]
[āŏ] > [ā]

ᴱQ. [ae], [ao] generally became [ā]; [a{eo}|ăō] > [ā|ō]

References ✧ PE12/14

Phonetic Rule Elements

[ae] > [ā] ✧ PE12/14 (ā̆ē̆ > ā)
[ao] > [ā]
[ăō] > [ō]

Phonetic Rule Examples

daorme > dōrme ăō > ō ᴱ√TAHA > tahorme > taorme > ᴱQ. torme ✧ QL/87