System windows usually soundproof well for several reasons. Quality profiles: mostly thermal-break aluminium whose multi-chamber structure blocks sound and which itself insulates better than ordinary aluminium. High-performance glass: double/multi-layer insulating, sometimes laminated; the air or inert-gas layer in insulating glass attenuates sound, and the laminated interlayer absorbs and blocks sound, especially high frequencies. Good sealing: multiple gasket lines block sound from entering through gaps, and well-designed/installed hardware forms an integral sealed space when closed. Professional design and installation: sized and configured per building need, and a professional team seals frame-wall gaps precisely. However, effect is also influenced by quality, workmanship and surroundings; poor quality or installation gaps hurt performance, and low-frequency noise (engine rumble) is relatively harder to block. Overall, system windows play an important role in improving the indoor acoustic environment and reducing external noise.