Answer:
the levels of use of voice recognition software
Step-by-step explanation:
Independent variable: In a scientific or psychological experiment, the term independent variable is defined as the variable that is being manipulated, controlled, or changed in an experiment. The independent variable affects directly the dependent variable, any change in the independent variable will cause or hamper the dependent variable.
Example: Time and age, etc.
In the question above, the independent variable is the levels of use of voice recognition software.