'For the examples given of the nasal vs. oral distinction this
appears from the etymology of each form as follows:

(Note: nasal are within paranthesis; long vowels not indicated)

H(A)R 'shark' *hanhaR, cf. Skt. shankú- 'stick, water animal'; but
HAR 'hair' *hâra, cf. OHG OS hâr, OE h´ær.

R(O)(hooked o)'corner' *wranhô (cf. Sw. vrå), cf., with alternation
according to Verner's Law, OIcel. rong (hooked o) *wrang-, OE wrang
(a), cf. Mod. Engl. wrong 'twisted'; but RO (hooked o) 'yard' *rahô,
cf. Sw. rå, MHG rahe.

Þ(E)L 'file' *þinhlô/*finhlô, cf. OHG fîhala, OE fêol, fîl, cf. Skt.
pimsháti 'hews out, carves'; but ÞEL 'woollen nap' probably *þela,
cf. OE þel 'a plank, plate,' Skt. talam 'surface, level, palm'.

F(E)R (hooked e) 'conceives' *fanhiR, cf. OIcel.inf. fá, Goth.
fahan, OHG OS fâhan, OE fôn *fanhan, cf., with alternation according
to Verner's Law, past part. OIcel. fengenn (cf. also Lat. pangô);
but FER (hooked o) 'sheep' *fahaz - PIE *pokos, cf. Gk. pêkos, pôkos
'wool, fleece'.

I 'in' *in, cf. Goth. OHG OS OE in; but ISA 'ice floes'(acc. pl.)
*îsanz, cf. OHG OS OE îs.

(O)RAR 'our' (fem.pl.) *unrôR *unzarôz (My Note: oblique case of the
reflexive pronoun - Proto-Norse adjective would be *unsaraR mas.sg.)
cf. Goth. unsar, OHG unsêr, OS unsa; but ORAR 'madness' *wôrôR, cf.
OHG adj. wuorag, OS wôrag, OE wêrig (Mod. Engl. weary).

(Ö)RA 'younger' (neut.) *junhiRô, cf. Goth. juhiza, and, with
alternation according to Verner's Law, OIcel. ungr, Goth. juggs, OHG
OS jung, OE geong; but ÖRA 'to vex' *wôrian, cf. orar above.

Þ(U)AT 'pressed' *þunh-; but ÞU 'thou' *þû, cf. Goth. þu, Lat. tu,
etc..

S(Y)NA 'to show' *siunian, cf. OIcel. sión, Goth. siuns; whereas
SYNA 'laps,' as a gen. pl. of the weak fem. *sýia, must go back to
*siujônô (cf. Goth.gen.pl. in -ono of fem. n-stems), with the root
vowel separated from the nasal consonant by the intervening -jô-.'

Seeing these etymologies should underscore the importance of this
type of modern linguistic research to the accurate phonological
representation of Old Norse. Given the advances that have been made
in this type of research, we should one day be able to achieve the
following: 1) produce a dictionary and printed texts in Old Norse
where nasality is indicated by regular and elegant means 2) produce
a standardized ancestor for Old Norse for comparative and literary
purposes, one which would be a tremendous help in understanding why
Old Norse is the way it is and why it is sometimes so confusing and
difficult to learn.

Regards,
Konrad.