Answer:
the independent variable
Step-by-step explanation:
Independent variable: In a psychological or scientific experiment, the independent variable is referred to as the variable that is being manipulated, controlled, or changed during the process of an experiment.
An independent variable is being manipulated by the researcher to see its effect on the dependent variable, and any manipulation to the independent variable leads to create a change in the dependent variable.
In the question above, the study including the type of room (conversation or silence) would be an independent variable.