Loudness is measured either by rating magnitude or by matching equal loudness

Evidence

Measuring loudness has been approached from two different directions: rating the relative loudness of sounds and matching the level of one sound to be equally loud as another sound. Because these approaches have been used to address somewhat different questions in the loudness literature, we discuss the different procedures in the context of their experimental questions. Rating methods have been typically used to measure how loudness changes with intensity, whereas matching has been used to measure how loudness changes with frequency. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 708

Categorization

• DEFINE: Establishes the two foundational experimental approaches to loudness measurement and which question each answers.