Steven Williams wrote:

>3. Quite a few languages hold phonemic consonant length contrasts--Italian, Japanese, Finnish and so on. Is it at all common, or even possible, to have a three-level distinction? In stops?

Interesting idea.  Here's a possibility:

/t/ realized as [d]

/t:/ realized as [t]

/t::/ realized as [t:] or maybe [?t] or some other "emphatic" pronunciation.

Would probably work best in a system that lacked contrastive voiced stops.  But how would voiced stops work, if they were also present?

/d/ realized as [D]?

/d:/ realized as [d] (overlap with /t/, not good)?

/d::/ realized a [d:] or [?d] or other emphatic.