Editing Absolute threshold of hearing (section)

== Minimal audible field vs minimal audible pressure ==

Two methods can be used to measure the minimal audible stimulus<ref name="Gelfand 2004"/> and therefore the absolute threshold of hearing.
Minimal audible field involves the subject sitting in a sound field and stimulus being presented via a loudspeaker.<ref name="Gelfand 2004"/><ref name="Kidd 2002">Kidd G. 2002.  ''Psychoacoustics'' IN ''Handbook of Clinical Audiology''. Fifth Edition.</ref> The sound level is then measured at the position of the subject's head with the subject not in the sound field.<ref name="Gelfand 2004"/>
Minimal audible pressure involves presenting stimuli via headphones<ref name="Gelfand 2004"/> or earphones<ref name="Durrant & Lovrinic 1984"/><ref name="Kidd 2002"/> and measuring sound pressure in the subject's [[ear canal]] using a very small probe microphone.<ref name="Gelfand 2004"/>
The two different methods produce different thresholds<ref name="Durrant & Lovrinic 1984"/><ref name="Gelfand 2004"/> and minimal audible field thresholds are often 6 to 10&nbsp;dB better than minimal audible pressure thresholds.<ref name="Gelfand 2004"/> It is thought that this difference is due to:
* monaural vs [[binaural (disambiguation)|binaural]]<!--link to disambiguation page appears to be the best choice for now--> hearing. With minimal audible field both ears are able to detect the stimuli but with minimal audible pressure only one ear is able to detect the stimuli. Binaural hearing is more sensitive than monaural hearing/<ref name="Durrant & Lovrinic 1984"/>
* physiological noises heard when ear is occluded by an earphone during minimal audible pressure measurements.<ref name="Gelfand 2004"/> When the ear is covered the subject hears body noises, such as heart beat, and these may have a masking effect.
Minimal audible field and minimal audible pressure are important when considering [[calibration]] issues and they also illustrate that the human hearing is most sensitive in the 2–5&nbsp;kHz range.<ref name="Gelfand 2004"/>