Ultrathin low-frequency sound absorbing panels based on coplanar spiral tubes or coplanar Helmholtz resonators

2014 ◽  
Vol 105 (12) ◽  
pp. 121901 ◽  
Author(s):  
Xiaobing Cai ◽  
Qiuquan Guo ◽  
Gengkai Hu ◽  
Jun Yang
Keyword(s):  
Low Frequency ◽  
Frequency Sound ◽  
Helmholtz Resonators

Design of efficient low-frequency sound absorbers using an array of Helmholtz Resonators

2020 ◽  
Vol 148 (4) ◽  
pp. 2798-2799
Author(s):  
Vidhya Rajendran ◽  
Tomás I. Méndez Echenagucia ◽  
Andrew A. Piacsek
Keyword(s):  
Low Frequency ◽  
Frequency Sound ◽  
Helmholtz Resonators

scholarly journals Low-Frequency, Open, Sound-Insulation Barrier by Two Oppositely Oriented Helmholtz Resonators

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1544
Author(s):  
Yi-Jun Guan ◽  
Yong Ge ◽  
Hong-Xiang Sun ◽  
Shou-Qi Yuan ◽  
Xiao-Jun Liu
Keyword(s):  
High Performance ◽  
Low Frequency ◽  
Single Layer ◽  
Sound Insulation ◽  
Architectural Acoustics ◽  
Frequency Sound ◽  
Helmholtz Resonators ◽  
Viscous Loss ◽  
Insulation Effect ◽  
Broadband Sound

In this work, a low-frequency, open, sound-insulation barrier, composed of a single layer of periodic subwavelength units (with a thickness of λ/28), is demonstrated both numerically and experimentally. Each unit was constructed using two identical, oppositely oriented Helmholtz resonators, which were composed of a central square cavity surrounded by a coiled channel. In the design of the open barrier, the distance between two adjacent units was twice the width of the unit, showing high-performance ventilation, and low-frequency sound insulation. A minimum transmittance of 0.06 could be observed around 121.5 Hz, which arose from both sound reflections and absorptions, created by the coupling of symmetric and asymmetric eigenmodes of the unit, and the absorbed sound energy propagating into the central cavity was greatly reduced by the viscous loss in the channel. Additionally, by introducing a multilayer open barrier, a broadband sound insulation was obtained, and the fractional bandwidth could reach approximately 0.19 with four layers. Finally, the application of the multilayer open barrier in designing a ventilated room was further discussed, and the results presented an omnidirectional, broadband, sound-insulation effect. The proposed open, sound-insulation barrier with the advantages of ultrathin thickness; omnidirectional, low-frequency sound insulation; broad bandwidth; and high-performance ventilation has great potential in architectural acoustics and noise control.

scholarly journals A new route to exposed thermal mass: Sound-absorbing poured concrete

2017 ◽  
Vol 38 (4) ◽  
pp. 408-420
Author(s):  
S Lombardo ◽  
JJ Orr ◽  
DA Coley ◽  
MJ Wood
Keyword(s):  
Sound Absorption ◽  
Low Frequency ◽  
Embodied Energy ◽  
Thermal Mass ◽  
Grid System ◽  
Acoustic Environment ◽  
Frequency Sound ◽  
Helmholtz Resonators ◽  
Operational Energy ◽  
Dependent Absorption

This paper investigates the novel possibility of utilising the structural concrete floor slab as a means of providing additional mid- to low-frequency sound absorption through the addition of cavities on the ceiling side, formed using flexible formwork, acting as Helmholtz resonators. Mid- to low-frequency sound absorption in rooms is typically achieved through the use of perforated plasterboard or a suspended tile-in-grid system. Such an approach can separate the room from the thermal mass of the ceiling above, leading to higher peak temperatures or increased cooling load. Suspended ceilings can also increase the embodied energy of the building and limit the potential for stack effect ventilation by reducing room height. In this work, frequency-dependent absorption coefficients of perforated concrete samples were measured using an impedance tube test. The results were found to agree with a theoretical analysis, suggesting that it would be relatively easy to predict the performance of perforations of other depths and diameters including those targeted at absorbing higher frequencies. Practical application: The measurements indicate that such a slab could be used as a practical replacement for perforated plasterboard or a tile-in-grid system. This would allow the slab to be tuned to the building’s acoustic performance and structural requirements. The approach has the potential to: (1) reduce the embodied and operational energy of buildings; (2) improve thermal comfort and (3) create a better acoustic environment in situations where surface robustness or longevity is important, for example public stairwells, pathways under roads and metro stations.

Sign in / Sign up

Export Citation Format

Share Document