Anything over 40ms will be noticeable. Just to give you an idea how sensitive our ears are - there’s a max distance certain instruments can sit away from each other in an orchestra booth or they start falling out of sync due to speed of sound delay
Speed of sounds is roughly 343 meters per second. Which means translates we can sense the delay difference of about 4-8 meters or so.
Which 100% corresponds with what you are saying. 20 meters is a 58ms-ish delay.
A 200ms is about 70 meters. Which would be like having conversation between people using one of those accidental sound projection features that sometimes happens with large open buildings like sports stadiums.
people talk in a cadence of around 100-200 words per minute. I guess we could say that is 300-600 syllables per minute. So that is about 200-100ms per syllable.
It all kinda lines up.