The noise detection algorithm for voice and video calls in Google Hangouts has been improved so instead of muting you altogether when typing, it will just filter out that noise and keep you on the line.
Traditionally, voice and video calls on Google Hangouts would mute you altogether if typing was detected, forcing you to hop back into the Hangout in order to unmute yourself. This can be a huge hassle if you're taking notes or working on the side while on a call, but still need to jump into the conversation every once in awhile.
Keep in mind that this update is only for Google Hangouts on the web. It wouldn't make much sense for a mobile improvement, because who even takes a Hangout call on their phone but types on the computer, but can't open a browser tab? In any case, pound away on those keys, angry typists. Google Hangouts has your back.
Source: Google for Work