Participant counts increase whenever new users sign into the Audience Web App or when users enter any interactive session. Generally, each participant count should correspond to a single user. However, it is not uncommon for users to use multiple devices when accessing Pigeonhole Live, thus inflating these numbers.
But if a user on a device enters a Q&A session, then exits and enters again, the participant count for this Q&A session will only register an increase of 1.
In addition, the participant count as an aggregate for the whole Pigeonhole, shown at the top of the main Insights page, will always be higher than the individual interactive session participant count.
This is because there will always be drop-offs from the main Agenda page to each individual interactive session page. In other words, participant counts for each session is a representation of a subset of users who first signed into the Pigeonhole, then entered that particular session.