Examination tools take a variety of forms, from the simple physical tools used to measure a speaker angle to the complex audio analyzer. An inclinometer uses gravity to measure vertical angle. The laser distance or range finder sends a beam and reads its reflection. Humidity can also be worth monitoring with a hygrometer for the same reasons because it affects HF air loss. The polarity tester, also known as the "phase popper", is a combination pulse generator and receiver. SPL meters integrate level over frequency and time into a single dB SPL reading. The standard frequency and phase responses of modern analyzers appear as single lines but are actually derived from the computations of around sixteen FFT analyzer modules. Single-channel measurements, referred to here as spectrum, require a single unknown: the output response. The wraparound provides context to the radial angle. Coherence is a statistical value, derived from the deviations between the amplitude and phase values in the averager.