system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If both people are on speakerphone during a video/phone call, how does the technology prevent each person from hearing their own voice being broadcasted from the other person's device?
gpt
it's called *echo cancellation* and one such method is to employ cross-correlation filtering.  This is where you take two (or more) streams of audio and apply a correlation filter (basically seeing where they match) and subtracting out what is filtered (e.g. subtract out the echo coming back).