The fact that you say “table” in the presence of a table and “chair” in the presence of a chair illustrates the tact relationship rather than audience control, although the presence of an audience may determine to a large extent whether or not the response is ever emitted.
A type of controlling variable with the following features:
The audience is usually a listener in the presence of whom verbal behavior is typically reinforced
It controls a group of response forms
Whether or not the listener provides reinforcement for the current response
The size or specific nature of the response forms controlled