Understanding the realistic noise reduction potential of acoustic plasterboard helps set appropriate expectations and guides proper specification. Acoustic performance measurement involves several technical parameters that quantify different aspects of sound transmission.
Measurable Acoustic Performance
The acoustic performance of plasterboard solutions is typically quantified using the following metrics:
Weighted Sound Reduction Index (Rw) Expressed in decibels (dB), the Rw value indicates a construction's ability to reduce airborne sound transmission across a range of frequencies. Higher values indicate better performance. While standard plasterboard partitions with single layers on both sides typically achieve Rw values of 34-38dB, equivalent constructions using acoustic plasterboard can reach 40-43dB—a noticeable improvement in practical terms.
When incorporated into more sophisticated systems with optimised stud configurations and appropriate cavity insulation, acoustic plasterboard can contribute to constructions achieving Rw values of 45-60dB, representing excellent sound isolation suitable for most residential and commercial applications.
Spectrum Adaptation Terms (C, Ctr) These correction factors adjust the Rw value to reflect performance against specific noise sources. The C term relates to high and medium-frequency sounds like voices or television, while Ctr addresses low-frequency noise such as traffic or music bass. Acoustic plasterboard typically performs better against high-frequency sounds (improved C values) than low-frequency noise, which requires additional treatment strategies.
Structure-Borne Sound Transmission For impact noise transmitted through building structures, acoustic plasterboard's contribution is measured using the weighted impact sound pressure level (Ln,w). When used in ceiling applications with appropriate floating floor constructions above, acoustic plasterboard can improve impact sound reduction by 5-10dB compared to standard boards.
Real-World Noise Reduction
Translating technical measurements into practical noise reduction expectations helps provide a realistic understanding of acoustic plasterboard's capabilities:
Speech Privacy Improvement For internal partitions within homes or between office spaces, replacing standard plasterboard with acoustic variants typically reduces speech transmission noticeably. While normal conversation might be clearly audible through a standard partition, the same conversation would be audible but unintelligible through a properly constructed acoustic plasterboard partition, providing reasonable privacy for most situations.
Television and Music Sound Reduction For typical domestic noise sources like televisions or moderate music, acoustic plasterboard systems can reduce perceived volume by approximately 40-60%, making a significant difference to neighbouring rooms. However, it's important to note that bass frequencies from subwoofers or amplified music may still transmit noticeably and require more comprehensive treatment.
Impact Noise Attenuation In ceiling applications, acoustic plasterboard combined with appropriate insulation can reduce the transmission of footfall and other impact noises from upper floors by approximately 30-50%, depending on the specific construction and the nature of the flooring above.
Contextual Factors Affecting Performance
Several factors significantly influence the actual noise reduction achieved:
Complete System Design The overall construction system dramatically affects acoustic performance. A single layer of acoustic plasterboard offers modest improvement over standard board, while double-layer systems with staggered seams can improve performance by 8-12dB. Incorporating resilient bars or independent stud frameworks to decouple the plasterboard from the structure can further enhance performance by 10-15dB.
Flanking Transmission Paths Sound often bypasses direct barriers through alternative paths such as ductwork, electrical outlets, or structural connections. Even the best acoustic plasterboard will deliver disappointing results if these flanking paths are not addressed. Comprehensive treatment of all potential sound transmission routes is essential for achieving satisfactory noise reduction.
Installation Quality Acoustic performance is particularly sensitive to installation quality. Research by the Building Research Establishment (BRE) has shown that poor workmanship can degrade acoustic performance by up to 15dB compared to laboratory test results. Proper sealing at perimeters, correct fixing patterns, and appropriate joint treatment are all critical to achieving the potential performance of acoustic plasterboard.
For optimal results, acoustic plasterboard should be viewed as one element in a comprehensive acoustic strategy that addresses all aspects of sound transmission. When properly specified and installed as part of a well-designed system, it can contribute to significant and satisfactory noise reduction for most conventional residential and commercial applications.
