Determination on sound transmission loss of sound insulation material / Nurul Asyikin Abu Bakar

This study has three major purposes which are to design an acoustic box, to
determine the measurement error of the acoustic box based on a standard sample
and to determine the sound transmission loss of selected sound insulation
material. Generally, the sound transmission loss is a measure of sound insulating
material's properties by transferring the sound energy through a barrier from one
medium to another. Sound transmission loss in investigated based on selected
sound insulation materials which are medium density fiberboard, polyurethane
foam, and gypsum board. In addition, these materials are selected based on their
availability in the market. In the first part, the acoustic box is designed by using
the medium density fiberboard and polyurethane foam is used to insulate the box.
Then, sound intensity formula is applied to determine the value of sound
transmission loss obtained from the recorded sound decibels by using sound
decibel meter. The measurement of sound transmission loss is based on three
different frequencies range at 2000 Hz, 3000 Hz and 4000 Hz which selected due
to the sensitivity on human ears where thickness of selected sound insulation
materials is uniform. In the second part, the polyurethane foam is used as a
standard sample by using the impedance tube as a reference value of sound
transmission loss. The measurement error of the acoustic box is determined by the
correction factor for the sound transmission loss of standard sample to determine
the corrected value of sound transmission loss of each selected material that
should be obtained from the acoustic box. In conclusion, polyurethane foam has a
very poor performance of sound transmission loss compared to medium density
fiberboard and gypsum board respectively. For recommendation, the acoustic box
can be enhanced by using the partition and the sample can be tested by using
different thicknesses.