Essentially, vocal languages are one-dimensional, thus easy to solve. Filter out disturbances, background noise, and train the machine to adapt to dialects, and

Essentially, vocal languages are one-dimensional, thus easy to solve. Filter out disturbances, background noise, and train the machine to adapt to dialects, and you're halfway home. Sign language is at least three-dimensional, it can embed more information. The ASL signs for "forget" and "because" differ only in how you mouth them - easy enough, but sometimes you even skip mouthing them because there is sufficient context. What's worse is the location of the hands can vary depending on how lazy the signer is feeling, so "forget" is supposed to be signed from the forehead but it can also be signed from some empty point in front of your shoulder, off a "phantom person"'s imaginary forehead. You rely on the listener to understand that you intend for there to be a phantom person there. Parsing sign language means you have to turn a 2D recording into a 3D model - even humans can have difficulty with this, parsing signs over Zoom - and you need to solve parsing facial expressions, reading lips and more. And you need the machine to be smart enough to detect the assignment of phantom persons to various locations around the signer. That's my impression as a deaf person anyway.