The default setting on the calendar is to allow Speakers Bureaus access to the speaker's calendar to place holds. What they see when they search the speaker's schedule is that the speaker will be "speaking in Dallas, Texas on July 24th at 7:00 PM". They don't see any of the other data related to the event (e.g. who the client is, etc.).
If you decide you still don't want to allow Directory Publishers to place holds on the speaker's calendar, follow the steps below to turn this setting off.
This will hide the speaker's calendar from the Directory Management reps, not allow them to place holds, and hide your schedule on any directory where your profile is published.