GB/T 19889.3-2005 "Acoustics - Measurement of sound insulation in buildings and of building elements - Part 3: Laboratory measurements of airborne sound insulation of building elements" specifies the method for measuring the airborne sound insulation performance of building elements such as walls, floors, doors, and windows (excluding small-sized elements) under standard laboratory conditions. This method requires a specialized sound insulation laboratory that can suppress sound wave transmission through flanking paths, thereby accurately measuring the sound insulation capability of the element itself. The measurement results provide sound insulation values that vary with frequency, which can be used for designing high-performance sound insulation elements, comparing the performance of different elements, or classifying them. It should be noted that due to differences between laboratory conditions and on-site environments, the data measured according to this standard cannot be directly used to predict sound insulation performance in actual buildings.