It occurs to me that modern Icelandic
does distinguish between some sound
solely with length.
The only difference between, for example,
"bruna" and "brunna" lies in the length of
the sounds. Yet I think one would distinguish
between those words in singing.
Bruna þú nú bátur minn...
not
Brunna þú...
I am quite confused now. Maybe there
is no problem. (Or maybe it makes some
difference that n is a voiced sound.)