I wonder how many bits of information could be packed into a single (nonsensical) syllable, without being too prone to misinterpretation.

https://en.wikipedia.org/wiki/English_phonology#Phonotactics

I think this is getting a little beyond my linguistics skills...

Edit: I suppose which syllables are easily corruptable depends on the medium: written hashes would require a different set of graphemes than spoken hashes would phonemes, for example, while memorised hashes would likely be different again. I wonder if there's been any research or anything into this.