The performance of fire alarm audible notification in a wide open space can be analyzed using a condition called free-field condition, where the sound pressure level (SPL) decreases roughly by a specific decibel value every time the distance from the source is doubled. Which of the following choices is the specific decibel value attributed to the free-field condition?
The free-field condition describes how sound propagates in an open space without significant reflections or obstructions. In such conditions, the sound pressure level (SPL) decreases by 6 decibels (dB) every time the distance from the sound source is doubled. This is a well-established acoustics principle known as the inverse square law.
the answer is D check the handbook 14-30
ANS: D 6dB. FPH 14-30
6dB Rule.
Correct answer is C : 6dB rule