OS. intervocalic [s] became [h]; [VsV|-Vs] > [VhV|-Vh]

OS. intervocalic [s] became [h]; [VsV|-Vs] > [VhV|-Vh]

In both (Old) Sindarin and (Old) Noldorin, an intervocalic [s] became [h]. This change is somewhat obscured, because later still [h] vanished after vowels. The clearest Sindarin examples are:

This sound change is the reason for the soft-mutation of initial s to h in Sindarin and Noldorin. It was also a factor in the use of “and” < √AS “beside”, which sometimes appears as ah before words beginning with a vowel: Athrabeth Finrod ah Andreth “The Debate of Finrod and Andreth” (PE17/41, MR/329). Clear examples are even more numerous in Noldorin:

As the last example shows, this sound change could sometimes result in irregular plurals; the irregular plural thely for S. thôl “helmet” (< *tholos?) may be a later example of such an irregular plural, though it was eventually reformed to regular plural thuil (PE17/188). Based on the Noldorin examples, it seems this phonetic development took place in the Old Noldorin/Old Sindarin period, as suggested by David Salo (GS/§4.71). Tolkien explicitly described this sound change in a couple places:

In Noldorin {however} s remained voiceless and became medial h (Outline of Phonetic Development [OP1], 1930s, PE19/34, note #28).
The sign ½ was reintroduced from the original Feanorian general alphabet only in late ON to denote h (at first absent in ON) redeveloped from initial kh, hy and intervocalic s (Feanorian Alphabet, 1930s, PE22/25).
The sound h did not exist in the older period. It redeveloped in ON (i) from d = kh > χ when it stood in absolute initial position in a word group; (ii) from older 9 = [ɧ] in the same position; (iii) for s between vowels (ibid., PE22/29).

A nearly identical sound change occurred in Welsh, where [VsV] > [VhV] > [VøV] (WGCH/§94ii). It seems that this change took place when s was final after a vowel as well:

N.B. N. dîs “bride” cannot be direct from ON. dîs since medial and final s were lost in Exhilic Noldorin. Its retention is probably due to blending with dissa. Thus dîs is a blend in early Exhilic of (which survives) and dess (which does not except as contributing to the sense “woman”, c.f. bess properly “wife”). ON. is a later development of under influence of dīr. Exhilic is from this and ON ndīs (EtyAC/NDIS).

Such developments must have been rare, however, since earlier still (perhaps even in Ancient Telerin) any final [s] vanished in polysyllables, so this sound change could only apply to monosyllables like ON. ndīs. It seems likely the mechanism was [-Vs] > [-Vh] > [-Vø]. Based on the above example, it seems the change of final [s] to [h] probably occurred later than between vowels, maybe in the Sindarin/Noldorin period rather than in Old Sindarin/Old Noldorin. The relative lateness of this change could help explain why the soft-mutation of s was to h rather than causing s to vanish, since the sound change at word boundaries probably occurred later, in the Sindarin/Noldorin period.

Conceptual Development: Intervocalic s is fairly common in Gnomish, which therefore could not have had this phonetic development, for example: G. ausirol “fortune”, G. nusiol “sagacious”, G. orosaura “sunrise”. The same is true of the Early Noldorin of the 1920s: ᴱN. Borosaith “Everhungry” and ᴱN. Broseliand. However, in the Early Noldorin of the 1920s, initial s- often (but not always) became h-, as noted by Roman Rausch in Historical Phonologies of Ilkorin, Telerin and Noldorin around 1923 (HPITN/§4.1.1):

There is no sign of this initial development in Sindarin/Noldorin, except in the soft-mutation of s to h.

Order (03100)

After 00700 [j] was lost after initial velars ᴹ✶khyelesē > khelesa > ON. kheleha Ety/KHYEL(ES)
After 01700 long final vowels were shortened ᴹ✶barasā́ > barasa > ON. baraha Ety/BARAS
After 02900 final [e] became [a] after single [s] and [st] ᴹ✶khyelesē > khelesa > ON. kheleha Ety/KHYEL(ES)

Phonetic Rule Elements

[VsV] > [VhV]

Phonetic Rule Examples

asa > aha VsV > VhV as(a) > a(h) > S. a ✧ PE17/41
asamaro > ahamaro VsV > VhV asmarō > S. ahamar ✧ VT48/20
asǭme > ahǭme VsV > VhV SAM > ahawv > S. aw ✧ PE17/173
l̥asu > l̥ahu VsV > VhV S-LAS > S. lhaw ✧ PE17/62
ŋgoroθūso > ŋgoroθūho VsV > VhV ñgor(o)-thūsō > Gorthu > S. Gorthaur ✧ PE17/183
otoso > otoho VsV > VhV Otos > S. odo- ✧ RC/384
otoso > otoho VsV > VhV otoso > S. odo ✧ VT42/25
pelesendore > pelehendore VsV > VhV PEL > S. pelennor ✧ PE17/65
tasǭre > tahǭre VsV > VhV tăsăre > tachaur > S. †taur/taor ✧ PE17/81
tindōmiselde > tindōmihelde VsV > VhV tindōmi-sel(dĕ) > tindúmhihel > S. Tinnúviel ✧ PE19/73
θolosi > θolohi VsV > VhV ÞOL > S. thely ✧ PE17/188
θūse > θūhe VsV > VhV thūsē > S. thû ✧ PE17/183

ON. intervocalic [s] became [h]; [VsV] > [VhV]

References ✧ PE19/34; PE22/25, 29

Order (04100)

After 01300 [j] was lost after initial velars ᴹ✶khyelesē > khelesa > ON. kheleha Ety/KHYEL(ES)
After 02400 long final vowels were shortened ᴹ✶barasā́ > barasa > ON. baraha Ety/BARAS
After 03900 final [e] became [a] after single [s] and [st] ᴹ✶khyelesē > khelesa > ON. kheleha Ety/KHYEL(ES)

Phonetic Rule Elements

[VsV] > [VhV] ✧ PE19/23 (-s- > -h-)

Phonetic Rule Examples

barasa > baraha VsV > VhV ᴹ✶barasā́ > barasa > ON. baraha ✧ Ety/BARAS
glisi > glihi VsV > VhV ᴹ✶g-lisi > N. glî ✧ Ety/LIS
gǭsa > gǭha VsV > VhV ᴹ✶gāsa > N. gaw ✧ Ety/GAS
kǭsa > kǭha VsV > VhV ᴹ√KAS > N. caw ✧ Ety/KAS
lasu > lahu VsV > VhV ᴹ✶lasū > N. lhaw ✧ Ety/LAS²
lūsien > lūhien VsV > VhV ᴹ√LOS > N. Lhuien ✧ Ety/LOS
nusina > nuhina VsV > VhV ᴹ√NUS > nusina > ON. nuhina ✧ EtyAC/NUS
oso > oho VsV > VhV ᴹ√OS > N. o ✧ Ety/OS
olosi > olohi VsV > VhV ᴹ√ÓLOS > N. elei ✧ Ety/ÓLOS
pelesi > pelehi VsV > VhV ᴹ√PEL(ES) > pelesi > ON. pelehi ✧ Ety/PEL(ES)
telesa > teleha VsV > VhV ᴹ√TELES > N. tele ✧ Ety/TELES
telesi > telehi VsV > VhV ᴹ√TELES > N. telei ✧ Ety/TELES
tindūmiselde > tindūmihelde VsV > VhV ᴹ✶Tindōmiselde > ON. tindūmhiell ✧ Ety/TIN
θelesi > θelehi VsV > VhV ᴹ✶thelesi > ON. thelehi ✧ Ety/THEL
θǭsa > θǭha VsV > VhV ᴹ✶thausā > N. thaw ✧ Ety/THUS
θūse > θūhe VsV > VhV ᴹ√THUS > N. thû ✧ Ety/THUS
xelesa > xeleha VsV > VhV ᴹ✶khyelesē > khelesa > ON. kheleha ✧ Ety/KHYEL(ES)
xīsislūme > xīhislūme VsV > VhV ᴹ✶χīsi-slōmē > N. Cílu ✧ PE21/32