The auditory system: perceptual aspects of hearing: intensity and loudness. 20-20000 hz being the range of hearing among humans. operception of intensity is related to the frequency of sound within this range. oother factors that have bearing on loudness perception. Have subject listen to sounds present to both ears through headphones. After gathering data from a number of trials using either methods a psychometric function can be plotted showing relationship between detection performance and intensity. Sound intensity hat produces 50% detection level is chosen for criterion threshold. Lowest detection threshold (highest hearing sensitivities) 2000 hz to 4000 hz. Sounds below optimal range display progressively higher detection thresholds: lowest frequency that can be heard lies between 10 hz and 20 hz. Sound frequencies higher than middle range also display progressively higher threshold values: anatomical and physiological determinants of minimal audibility curve ofactors responsible for u shaped profile of minimal audibility curve.