Apparatus, systems, articles of manufacture, and methods for viewer authentication are disclosed. An example system includes a comparator to access audio metering data received from a user device and determine a level of exposure of a user of the user device to a program based on the audio metering data. The example system also includes a calculator to determine a weighting score based on the level of exposure. In addition, the example system includes a tallier to access voting data received from the user device for a ballot presented in the program and scale the voting data based on the weighting score.