Absolute threshold of hearing (최소 가청값, 최소 가청치)

Absolute threshold of hearing 

(auditory threshold, 최소 가청값, 최소 가청치)

최소 가청값은 평균적인 귀로 들을 수 있는 가장 작은 음압 레벨이며, 

공기중에서는 일반적으로 20 µ Pa (micropascals) = 2×10−5 pascal (Pa)이다.

(대략적으로, 3m 떨어진 곳에서 모기가 날아다니는 소리의 크기.)

0 dB(SPL) = 20 * log10( 20µPa / 20µPa)

94 dB(SPL) = 20 * log10( 1Pa / 20µPa)

(출처: http://en.wikipedia.org/wiki/Absolute_threshold_of_hearing)

The absolute threshold of hearing (ATH) is the minimum sound level of a pure tone that an average ear with normal hearing can hear with no other sound present. The absolute threshold relates to the soundthat can just be heard by the organism. The absolute threshold is not a discrete point, and is therefore classed as the point at which a response is elicited a specified percentage of the time. This is also known as the auditory threshold.

The threshold of hearing is generally reported as the RMS sound pressure of 20 micropascals, or 0.98 pW/m² at 1 atmosphere and 25 °C. It is approximately the quietest sound a young human with undamaged hearing can detect at 1,000 Hz. The threshold of hearing is frequency dependent and it has been shown that the ear's sensitivity is best at frequencies between 1 kHz and 5 kHz.