PSYCH 3A03 Lecture Notes - Audiology, Pressure Measurement, Particle Displacement
5 Nov 2013
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Px absolute pressure of incident sound. When pref is 20 pa, we refer to this measure as db spl (spl sound pressure level; 20 pa implied) For a 1khz sinusoid at the threshold of human hearing (0db spl), air particle displacement is ca. 7. 68 x 10-8m (only very slightly being displaced), also implies that you have 20 pa as an incidence pressure. 1 angstrom ( ) = the diameter of a hydrogen atom, . :at threshold of hearing air particles are displaced ~ca 768 . The ratio of sound pressure that causes permanent damage from short exposure to the limit (threshold) that undamaged human ears can detect is more than one million (>106) Because power is proportional to the square of the pressure, the ratio of the maximum power that causes permanent hearing damage to the minimum power that is just audible is more than one trillion (>1012)
