One of the most important early differences between Old Norwegian and
Old Icelandic is that
h in the
consonant combinations
hl-,
hn- and
hr- was lost in Old Norwegian around the 11th century, while being preserved in Old Icelandic. Thus, one has e.g. Old Icelandic '
slope', '
curtsey' and '''' 'ring' and Old Norwegian ''
, and , respectively.'' Many Old Norwegian dialects feature a height based system of
vowel harmony: Following stressed high vowels (, , , , , ) and diphthongs (, , ), the unstressed vowels and appear as
i,
u, while they are represented as
e,
o following long non-high vowels (, , , , ). The situation following stressed short non-high vowels (, , , , , ) is much debated and was apparently different in the individual dialects. The
u-umlaut of short (written
ǫ in normalized Old Norse) is not as consistently graphically distinguished from non-umlauted as in Old Icelandic, especially in writings from the Eastern dialect areas. It is still a matter of academic debate whether this is to be interpreted phonologically as a lack of umlaut or merely as a lack of its graphical representation. ==Old Norn==