Is it 6 decibels? The effect of pressure doubling on exterior to interior transmission loss values.

Abstract

When calculating sound levels inside a building due to external sources, should some value be added to the expected sound level? ATSM E966 recommends adding 6 dB to this level. It has been theorized that this is due to pressure doubling. The effect of pressure doubling on the calculated exterior to interior sound transmission in the direct field is, however, often misunderstood. Most texts on the subject simply list a 5- or 6-dB correction factor that is applied to the transmission loss value. The reasoning of this particular number is neither expounded upon nor explained. This paper investigates and explains this correction factor.