Tobin sells the audiojacks for institutional use with lesson plans and prompts, but it's also available to individual users in mobile app form. There's one free available in each category, and an annual subscription costs $14.99. Lately, he said, he's seen a surge in downloads and mail from users who like listening to them for no other reason than to space out. Consider it an active form of meditation, where you can choose to imagine any visuals you like or none at all.