The ear's extremely wide range of sensitivity is one of the most striking aspects of audition. The ear is sensitive to a range of intensities from about 0 dB Sound pressure level (SPL) to roughly 140 dB. While the general relationship between auditory sensitivity and frequency is well established, one should be aware that subsequent experiments have provided detailed estimates of absolute sensitivity in the lower- and upper-frequency ranges. The graph is the conventional audiogram used in audiology. Actually, the term "audiogram" may legitimately be used to describe any graph of auditory sensitivity as a function of frequency. The essential finding of gap detection thresholds (GDT) experiments is that auditory temporal resolution is on the order of 2 to 3 ms. Such GDTs are obtained when the noise signal contains the higher frequencies and when these are presented at levels that are adequately audible.