An unusual vowel contrast

Geoff Lindsey writes:

I do think that the official IPA chart is crowded with symbols which exist not so much for good acoustic or linguistic reasons as to fill the slots implied by its tongue-space framework.

For instance, I’m not sure that languages ever contrast ɨ and ɯ; the unrounded close non-front vowel of languages like Turkish and Vietnamese is sometimes transcribed as ɯ and sometimes as ɨ.

A while ago, I downloaded PHOIBLE‘s database, since they don’t have a search function on the site. Searching the database for inventories from the same source that contain both ɨ and ɯ, I get:

• Apatani (RA)
• Bora (SAPHON)
• Kenyang (PH)
• Kilba (GM)
• Kod̩agu (RA)
• Matses (PH)
• Matsés (SAPHON)
• Miraña (SAPHON)
• Mishmi (RA)
• Nimboran (UPSID)
• Sedik (PH)
• Sema (RA)
• Southern Ute (PH)
• Tangkul Naga (RA)
• Wayana (SAPHON)

This is of course inconclusive, since the databases PHOIBLE draws from are unreliable. The Apatani vowel inventory sourced from RA in PHOIBLE differs wildly from the more usual one given in this paper.

However, this paywalled study claims that Bora really does have this contrast. SIL’s grammar of Kenyang claims that the language contrasts all of /ɨ ɯ u/, which is an even stronger example than Nimboran, the standard example of a language with such a contrast. (Nimboran has a six-vowel system with no rounded vowels, as does Matses.)