Where to adjust playbooks so it does not sound as a site visitor navigates?

If you're not looking to have your visitors be "pinged" every time they receive a message from either your bot or your teammates, Drift does have a setting that allows you to toggle this on and off!

You can find this nested in Settings - App Settings - Drift Widget - Advanced Settings. About halfway down, you'll see a toggle for "Play sounds for new messages"

Toggling this off will prevent that sound from pinging your visitors while they click around your site and interact with your bot. The only thing to note is that because this is a universal setting, it will affect all playbooks and conversations. For more information, you can check out this help doc as well!