Loudness is the perceptual strength of a sound, most often associated with physical amplitude (Florentine, 2011). Equal loudness contours (or equal loundness functions) illustrate the SPLs of tones across the frequency range of hearing that are perceived as equally loud by listeners across different frequencies, and are a tool for investigating the frequency-dependence of hearing. ELoC experiments are conducted to test what level of a comparison tone is required by a listener for the comparison tone’s perceptual loudness to equal that of a different, standard tone. This test is repeated across a range of frequencies. The level of the comparison tone (in dB) is then plotted as a function of frequency to create an ELoC. ELoCs are used to inform the creation of auditory weighting functions and are a valuable aspect of assessing potential negative impacts of sound on an auditory system.