Differential Pitch Sensitivity of the Ear

Abstract

Differential pitch sensitivity is defined as the minimum percentage change in frequency which can be detected by the ear. The value of this ratio was measured over a frequency range from 32 cycles to 11,600 cycles and from the thershold of audibility to a sensation level of 90 db. in the case of ten normal ears. A number of subsequent observations were made using binaural and bone conductions timuli. In a region above 1,000 cycles and above a 20 db. sensation level the minimum detectable variation Δ/f is approximately constant at a value of .003. Below 1,000 cycles the function Δf is approximately constant for any one sensation level. Binaural and bone conduction stimuli tend to increase the sensitivity of the ear to pitch changes in the general region below 500 cycles but above this region there is very little effect. The errors encountered in this type of measurement are discussed, together with the design and technique necessary to minimize such effects. A series of observations taken with modified apparatus show the effect of several such factors upon the results.