On the most recent release of the Safari web browser, Apple has disabled the auto-play of sounds and video, including the audible notifications for the Olark chat widget. You can fix this by following the steps below.

  1. In Safari, navigate to chat.olark.com.
  2. Open the Safari Preferences and then click on the websites tab.
  3. Click on “Auto-Play” in the General section.
  4. Change it from “Stop Media with Sound,” to “Allow all auto play.”

Here is a handy gif showing this process in action:

safari preferences gif