My tool is local: it measures the time from when JS says "send this to the speaker" until JS receives that audio back from the mic. It's the client-side round-

My tool is local: it measures the time from when JS says "send this to the speaker" until JS receives that audio back from the mic. It's the client-side round-trip latency. (As far as I know, there is no way to get the browser to tell you this latency, and you have to measure it.)