Enhancing the low frequency sound absorption of a perforated panel by parallel-arranged extended tubes. Experiment study on the sound absorption characteristic of perforated panel with ladder tube bundles. The perforated panel resonator with flexible tube bundles and its Appliations. Lu Y, Tang H, Wang Q, Tian J, Qu Y, Qiu B. Micro-perforated absorbers with incompletely partitioned cavities.

Enhancing micro-perforated panel attenuation by partitioning the adjoining cavity.

Sound transmission through a microperforated-panel structure with subdivided air cavities. In12th International Congress on Sound and Vibration 2005. Acoustical properties of microperforated panel absorbers with various configurations of the back cavity. Yairi M, Sakagami K, Morimoto M, Minemura A. Design guide of single layer micro perforated panel absorber with uniform air gap. Optimization of multiple-layer microperforated panels by simulated annealing. Pilot study on wideband sound absorber obtained by combination of two different microperforated (MPP) absorbers. Sakagami K, Nagayama Y, Morimoto M, Yairi M. Increasing of the frequency band of sound absorption for flat multi-layered absorbers consist of porous material, perforated panel and air-gap. Optimization of flat multi-layer sound absorber by using multi-objective genetic algorithm for application in anechoic chamber. Enhancing low frequency sound absorption of microperforated panel absorbers by using mechanical impedance plates. Double resonant porous structure backed by air cavity for low frequency sound absorption improvement. Effects of carbon nanotube loading on cellular structures and sound absorption of polyurethane foams. Low loading of carbon nanotubes to enhance acoustical properties of poly(ether)urethane foams. Providing an optimal porous absorbent pattern to reduce mid to low-frequency sounds. Effects of noise on mental performance and annoyance considering task difficulty level and tone components of noise. Jafari MJ, Sadeghian M, Khavanin A, Khodakarim S, Jafarpisheh AS. Modelling and evaluation of light railway system’s noise using neural predictors. Designing, constructing and testing of a new generation of sound barriers. Use of municipal, agricultural, industrial, construction and demolition waste in thermal and sound building insulation materials: a review article. Massoudinejad M, Amanidaz N, Santos RM, Bakhshoodeh R. The characteristics of pollution in the big industrial cities of Kazakhstan by the example of Almaty. Results show that the Fibonacci sequence is an optimum candidate to design a resonator-based sound absorber in low-frequency noise.Īiman N, Gulnaz S, Alena M. Analytical solutions based on the modified equivalent electrical circuit theory is used to calculate the sound absorption coefficient of the proposed panel with numerical experiments in MAPLE and COMSOL Multiphysics softwares to validate the proposed overall approach. In this paper, Fibonacci sequence is utilized to investigate Helmholtz resonator arrangement to increase both the amount of sound absorption coefficient and frequency bandwidth of absorption without changing the total volume of resonator array with equal size units. In addition, Fibonacci sequence is a famous mathematical model which describes the shape/ratio of different phenomena which exist in nature. On the other hand, it seems that engineering science can be developed by nature inspiration. Hence, the consideration of suitable sizes for each resonator in an array panel consisting of unequal size units is a key point to widen the frequency range of sound absorption. Therefore, a resonator array panel with equal size units has insufficient performance in a wide frequency range. In this regard, Helmholtz resonator array is a well-known structure but the maximum performance of each resonator unit in an array panel can only be achieved at resonance frequency that is dependent on its size. It is more attractive if it is possible to produce sound absorbing structures that perform well for a wide frequency range, especially in low-frequencies. Sound absorbing elements commonly used to make quieter spaces are very desirable for high-frequency noise control.

Natural fibonacci sequences