Study of the compatibility between sound insulation performance and ventilation performance in gaps by installing nonwoven fabrics

• Thin nonwoven fabrics are installed in the gaps of windows and doors.
• The relations between the sound insulation and air ventilation are discussed.
• An improvement in the sound insulation performance is obtained.
• The thin nonwoven fabrics have low flow resistivities.
• The sound insulation effects are obtained with thin nonwoven fabrics.

Gaps, slits, and openings for natural ventilation that occur around doors and windows cause sound leakage and decrease sound insulation performance. However, if airtight materials are used to close these gaps, as is typical, the ventilation performance is lost. In the gaps, the particle velocities become large, and this phenomenon is reported as the “gap effect.” Furthermore, it is suggested that the sound insulation performance is improved by suppressing the particle velocities in the gaps with breathable sound-absorbing materials. Therefore, a balance between the suppression of sound leakage and maintaining the air ventilation is obtainable by considering the balance between the total equivalent clearance and the flow resistivities of the breathable sound-absorbing materials. In this study, for the installation of thin nonwoven fabrics as a breathable material in the gaps, improvements in the sound insulation performance and the amount of ventilation as the total equivalent clearance area are verified. Additionally, the relations between the sound insulation performance and the air ventilation performance using these nonwoven fabrics in the gaps are discussed. As a result, an improvement in the sound insulation performance is obtained while maintaining the air ventilation performance by installing thin nonwoven fabrics that have low flow resistivities because the large particle velocities are effectively suppressed in the gaps.