Ultra-broadband acoustic ventilation barrier with multiple mechanisms

We report the realization of a type of ultra-broadband acoustic ventilation barrier. The designed ventilation barrier consists of dual-layer periodic unit cells that can reduce sound transmittance by over 10[Formula: see text]dB in both the ranges of 540–1430 and 1740–2090[Formula: see text]Hz. The origin of sound insulation arises from the reflection and absorption of sound, which are caused by the bandgap and dissipative eigenmodes of the unit cell, respectively. The design of multiple mechanisms makes the ventilation ratio of the barrier reach 28.8%. In addition, the working bandwidth of the ventilation barrier can be further optimized by increasing the layer number and tuning the interlayer distance. As an example, an optimized ventilation barrier composed of 4 layers of periodic unit cells with different interlayer distances is observed to exhibit sound insulation in the whole range of 520–2120[Formula: see text]Hz, where the fractional bandwidth (the ratio of the bandwidth to the center frequency) has reached 121.2%. The simulation and experimental results match well with each other. The designed ventilation barrier shows both advantages of ultra-broadband sound insulation and ventilation, which may have a great potential in environmental protection and architectural acoustics.