Sometimes people ask if they should be measuring both the visual and aural carriers when they run this test. It certainly doesn't hurt and it provides additional information. However, the rules only require that the visual carriers be measured.
This is the only test that is required during specific time frames. It needs to be
conducted during the months of either January or February and again in either July or August. There should be no
more than 7 months between tests.
4 tests are to be performed in intervals of no less than 5 nor more than 7 hours over a 24 hour period.