The Information of Elementary Auditory Displays

Whereas the ear's sensitivity for detecting a difference in frequency between two tones is remarkably acute, the ability of listeners to identify (and name) tones presented in isolation is relatively poor. When the frequency of a single tone (in the frequency range 100–8000 cps) is varied in equal logarithmic steps (and when the sound level is arbitrarily varied to reduce loudness cues), the amount of information transferred is about 2.3 bits. (The equivalent proficiency of response for an informational transfer of 2.3 bits is perfect identification among only 5 tones.) The amount of information that can be transferred is, within rather wide limits, independent of the number of tones and the range of frequencies employed.