PNC 6
PNC 6 :
An abbreviation for preferred noise criterion, a unit used in engineering to measure the level of background noise in rooms or other enclosed spaces. Introduced in 1971, the unit is similar to the older noise criterion (NC), but a PNC rating requires lower levels of high and low frequencies than the corresponding NC rating. PNC ratings below 40 are generally required for residential or classroom spaces. PNC ratings are typically 10-15% lower than raw measurements of the sound level in decibels
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