Editing Absolute threshold of hearing (section)

== Temporal summation ==

Temporal summation is the relationship between stimulus duration and intensity when the presentation time is less than 1 second. Auditory sensitivity changes when the duration of a sound becomes less than 1 second. The threshold intensity decreases by about 10&nbsp;dB when the duration of a tone burst is increased from 20 to 200 ms.

For example, suppose that the quietest sound a subject can hear is 16&nbsp;dB SPL if the sound is presented at a duration of 200 ms. If the same sound is then presented for a duration of only 20 ms, the quietest sound that can now be heard by the subject goes up to 26&nbsp;dB SPL. In other words, if a signal is shortened by a factor of 10 then the level of that signal must be increased by as much as 10&nbsp;dB to be heard by the subject.

The ear operates as an [[energy]] detector that samples the amount of energy present within a certain time frame. A certain amount of energy is needed within a time frame to reach the threshold. This can be done by using a higher intensity for less time or by using a lower intensity for more time. Sensitivity to sound improves as the signal duration increases up to about 200 to 300 ms, after that the threshold remains constant.<ref name="Gelfand 2004"/>

The timpani of the ear operates more as a sound pressure sensor. Also a microphone works the same way and is not sensitive to sound intensity.