Doing voice processing is much much more computationally expensive than scanning text, and has a much higher error rate, so it would make little sense for Googl

Doing voice processing is much much more computationally expensive than scanning text, and has a much higher error rate, so it would make little sense for Google to do that. More likely explanations could be: - Your topic is a common/popular one, so it's statistically likely that Youtube mentions it. - Other people that (text-)search the same things as you tend to watch these videos (i.e. you have been put is some category or other). - You did not search for it, but your phone correspondant did, and Youtube/Google tries the same suggestions on you because you're linked (see: there are other and less costly ways for Google to be creepy!).