Being able to silently communicate has a number of benefits, both for dealing with the extremely rare profoundly deaf non-lip-reader-who-doesn't-read-and-also-doesn't-have-an-interpreter, but also just for talking with people when you're supposed to be quiet.
I've seen rudimentary sign-like languages develop with carnival game buskers, who can't shout to each-other during low-business times due to distance. I'm sure other industries might have the same.
The military has a few hand signals for when silence is necessary.
Also factory workers, because of ambient noise. Sometimes even screaming at the top of your lungs doesn't help you be heard.
And interacting with non-humans, where consistent gestures can aid with understanding of speech on their part (not to mention understanding their body language back at you.)
Being able to silently communicate has a number of benefits, both for dealing with the extremely rare profoundly deaf non-lip-reader-who-doesn't-read-and-also-doesn't-have-an-interpreter, but also just for talking with people when you're supposed to be quiet.
I've seen rudimentary sign-like languages develop with carnival game buskers, who can't shout to each-other during low-business times due to distance. I'm sure other industries might have the same.
The military has a few hand signals for when silence is necessary.
Also factory workers, because of ambient noise. Sometimes even screaming at the top of your lungs doesn't help you be heard.
And interacting with non-humans, where consistent gestures can aid with understanding of speech on their part (not to mention understanding their body language back at you.)