Airborne
sound insulation test (walls & floors): A controlled
noise is generated by an amplifier and loudspeaker across a broad range of
frequencies. The generated noise is very loud and can be in excess of 100dB.
Initial measurements are taken using a Sound Level Meter within the ‘source
room’ followed by further measurements in the ‘receiver room’ on the other side
of the wall or floor under investigation. The source room speaker position is
then changed and the measurements repeated either side of the partition under
test.
Background noise measurements are made
using a sound level meter in the receiving room and are used to apply
appropriate corrections for external sound such as traffic noise. Similarly the
reverberation time (the time taken for sound to decay by 60dB) is measured within
the receiving room using the sound source and a sound level meter to determine
the corrections that must be applied to account for the characteristics and
absorptiveness of the room.
The difference in the two airborne
noise levels (for walls and floors), corrected for background and reverberation
characteristics determines the airborne sound insulation performance of the
wall, or floor. A greater
airborne noise difference between the source room and the receiver room
determines a higher airborne sound insulation performance.
Impact sound transmission test (floors only): This test is
different, a calibrated ‘tapping machine’ which comprises of five 'hammers'
driven up and down by a cam and electric motor is used to "tap" the
floor surface by applying a known force on the floor structure. The machine is
placed in several pre-determined positions. The resulting noise is measured in
the dwelling below, using a sound level meter.
Background noise measurements are made
using a sound level meter in the receiving room and are used to apply appropriate
corrections for external sound such as traffic noise. Similarly the
reverberation time (the time taken for sound to decay by 60dB) is measured within
the receiving room using the sound source and a sound level meter to determine
the corrections that must be applied to account for the characteristics and
absorptiveness of the room.
The measured noise levels in the
receiving room (for impact floors tests), corrected for background and
reverberation characteristics determines the impact sound insulation
performance of the floor. For the
impact noise the lower the measured level, the better the performance as less
sound is being transmitted into the dwelling below.
