What is involved in making a measurement of sound transmission loss in a building?
A loudspeaker and amplifier are used to generate loud random noise in a room on one side of the partition under test. For at least 16 frequencies, starting at 125 Hz and ending at 4000 Hz, the average sound pressure level is measured in this source room and the room on the other side of the partition. The difference between these two sets of numbers is called the noise reduction. The larger the area of the partition separating the two rooms, the more sound energy will pass through it. The more absorptive the receiving room, the lower the sound pressure level in that room will be. The noise reduction values are therefore adjusted to compensate for these two factors to give the sound transmission loss; this is a measure of the sound power transmitted per unit area and is independent of the area of the partition and the receiving room properties. The transmission losses are used to calculate the sound transmission class. ASTM E597 describes a quicker procedure, which gives a number very c
