Brian self-records the Philosophers Notes. The +1 and 101 classes that Brian records in the studio are converted into audio format, so that's his voice too.
There might also be some miscellaneous content from Team Optimize that has been converted into audio as well, namely Alexandra's meditations, or Michaels coaching content!
Lastly, for curious souls, the man behind the Philosopher's Notes intros such as "You're listening to the Philosophers Note on..." is named Seth! He's been supporting our PN production for MANY years!!
Additional questions? Reach out!