The threshold of hearing is the least sound intensity that an average ear can respond to. The threshold of pain is the maximum loudness that an average ear can withstand with physical damage. It is for this reason that loudness is measured on a power of ten scale similar to the Richter scale for measuring earthquakes. The intensity level is the number of factors of 10 that the intensity is greater than the threshold of hearing. It is named the Bel .
All mammals have two ears.
Direction may be determined by comparing the loudness and phase of a sound reaching the two ears. Subjective Tones Subjective tones are virtual tones perceived whenever two or more harmonics of a tone are sounded together. Although these terms are often used interchangeably and the overall effect is the same, they are fundamentally different physical phenomena. This is determined by The number of overtones present that are harmonics, the number of overtones that are inharmonic, and the relative intensities or strengths of the overtones. Analysis and Synthesis of Sounds Analysis is the process of dividing a complex wave into its fundamental frequency and its various overtones and determining the relative strengths of each.