[briansm]

Reminds me of the old IBM 'RECOVC' codec from around 2000 where they compressed Mel-bank speech.

https://ieeexplore.ieee.org/document/7075313

All the patents around that are long-dead so good time to do an updated version I guess.

If you wanted to do something similar but with way lower bitrates (e.g. 300bps), then look at the NRV codec:

https://www.researchgate.net/publication/224209493_300_bps_n...

[briansm]

Addendum, playing with it at the 'low quality' end, it generates recognizable speech even down to 200bps and in some cases 100bps. crazy.