You can create audiences based on conversations, they will be based on monitoring queries.
In step 2: Define your audience of your report creation:
1. Select the Advanced Audience Manager
2. Select Conversations
3. Type in the keywords you'd like to monitor and separate each by either a comma or by hitting enter. This could be the keywords/hashtags, handle mentions (Twitter handles) or URLs.
Note: The search will be limited to 20K tweets and will find matches for the past 30 days.