Hearing thresholds were first systematically mapped in the 1930s using two distinct measurement paradigms

Evidence

By the 1930s, a number of scientists had made measurements of auditory thresholds at various frequencies. The data shown in Figure 2–9 are a compilation of these measurements adapted from Sivian and White (1933). These measurements illustrate the minimum detectable sound pressure level in dB SPL of young human listeners as a function of frequency when measured in the free field and over headphones. For the minimum audible field (MAF) measurements, sounds were presented over a loudspeaker (i.e., in the free field) and calibrated at a location 1 m away from the speaker. Note that for these free-field measures, the listeners were able to use both ears. For the minimum audible pressure (MAP) measurements, sounds were presented monaurally (i.e., to a single ear) over headphones, and measurements were based on a calibration reference level at the tympanic membrane. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 243

Categorization

• DEFINE: Defines MAF versus MAP as the two classic absolute-threshold measurement paradigms, distinguished by free-field binaural versus headphone monaural presentation.