Teaching Intro to Linguistics is probably one of the most challenging but fun things I’ve done in a long time. Usually I can answer any question my students come up with, but once in a while they stump me.

Case in point: the other day, one of my students asked if we new phonemes ever get discovered and the IPA chart gets updated.

As far as I know, the last time the International Phonetic Alphabet was updated was in 2005. As far as vowels go, pretty much everything that’s possible to make with the vocal tract is attested.

Consonants? Well, there are some spaces on the IPA chart that are grey: those are physically impossible to produce, like bilabial lateral fricatives. There’s also some spaces that are white: those are physically possible to produce, but unattested, like labiodental trills. And there’s also some unofficial symbols, like the one for the retroflex lateral flap. So I suppose at some point lost in history some language probably had a labiodental trill, but such languages don’t seem to be common these days. And I suppose that the unofficial symbols could rise to official status, but again such sounds are so rare in the world’s languages this might not be practical or useful.

Some sounds, like the whistled speech of the Silbo Gomero or the Pirahã don’t have symbols in the IPA. I suppose a diacritic for “whistled speech” could be added to the IPA, but I’m not sure it’s necessary. As far as I know, the whistled speech in those languages is a special register of communication, and doesn’t contrast the same way [p] and [b] contrast in English pat versus bat.