30 seconds/recording: presumed average recording length
1,000,000 seconds: a bit higher than the total number of seconds of audio recorded
8 months: Amount of time service was around
1,000,000 seconds / 30 seconds/recording = 33,333 recordings
33,333 recordings / 8 months = 4,166 recordings/month = 138 recordings/day.
Edit: for some reason, Josh Constine at TechCrunch decided to reference my arithmetic. I just want to make sure it's clear that I'm happy for Arda and Alexander for finding an exit, and that startups are hard. I'm not trying to be snarky.
on the other hand, presumably they didn't decide to fuck over a bunch of grannies for fun (even if they did go to palantir). so it was an acquihire. so maybe some part of the description was more positive than the unvarnished truth?