Results 211 to 220 of about 22,575 (260)
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Mechanisms for Anomalous Low-Frequency Absorption of Sound in Seawater
The Journal of the Acoustical Society of America, 1971Various processes of a chemical nature contributing to the anomalous absorption of seawater are reviewed. The contributions of most of these processes to the absorption coefficient can be predicted quantitatively on the basis of various physical-chemical data obtained from both acoustical and other relaxation measurements.
Ernest Yeager, Fred Fisher
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A double porosity material for low frequency sound absorption
Composite Structures, 2020Abstract This work designs a double porosity material (DPM) composed of two types of pores, i.e., the micro-pore from the porous layer and the meso-pore made by the labyrinthine channel. The both loss mechanisms of two different pores are combined to explore the low frequency sound absorption.
Honggang Zhao +6 more
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Adaptive metamaterials for broadband sound absorption at low frequencies
Smart Materials and Structures, 2018Abstract We propose and design a new adaptive sound absorption metamaterial targeting broadband airborne noise at extremely low frequencies. The metamaterial consists of two piezoelectric smart elements: a circular aluminum membrane with surface-bonded piezoelectric films controlled by shunting circuits enclosed with an air cavity for
Yunhong Liao +3 more
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Helmholtz resonator array for low-frequency sound absorption
The Journal of the Acoustical Society of America, 2006An array of Helmholtz resonators is often used for reducing low-frequency noise because of the high performance at its resonance frequency. One of the very attractive characteristics of the resonator array is that its effective frequency band is much wider than what can be obtained by a single resonator.
SangRyul Kim, Yang-Hann Kim
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A microstructure material design for low frequency sound absorption
Applied Acoustics, 2018Abstract The acoustic properties of an air-saturated porous material depend on its microstructure and the thickness of the sample. Thick samples of conventional acoustic materials are required to achieve good absorption at low frequencies. This study suggests a new micro-structure for the design of low-frequency resonant acoustic absorbers.
Dupont, Thomas +3 more
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Low frequency sound absorption by decorated membrane resonators
2021For over a decade, spongy and fibrillar materials have dominated the sound absorption market. These materials, however, fail to tackle noise below 500Hz, and low frequency sound absorption remains one of the most challenging topics in the field of acoustics.
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Maximum Sound Absorption by a Monopole in a Room at Low Frequencies
Acoustical Physics, 2020The article considers the problem of sound absorption by a monopole in a room with perfectly hard walls. The radiation impedance of a monopole in the form of a piston built into one of the walls was found. The impedance of the monopole is calculated that ensures the maximum damping constant of the room first natural resonance.
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Sound Absorption at Low Frequencies: Room Contents as Obstacles
Building Acoustics, 2007A description is given of sound absorption in small-furnished rooms at low frequencies. The objective of the work was to characterise room absorption due to contents such as furniture and to develop a model of absorption appropriate for a modal description of contained sound fields at low frequencies. In this paper, a preliminary study of the influence
Gustavo da S. V. de Melo +2 more
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Low-frequency sound absorption of a tunable multilayer composite structure
Journal of Vibration and Control, 2021Our work investigates a tunable multilayer composite structure for applications in the area of low-frequency absorption. This acoustic device is comprised of three layers, Helmholtz cavity layer, microperforated panel layer, and the porous material layer. For the simulation and experiment in our research, the absorber can fulfill a twofold requirement:
Hanbo Shao +4 more
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Low-frequency sound absorption in Pacific Ocean water
The Journal of the Acoustical Society of America, 1975Using the 200-liter resonator, measurements of Pacific Ocean water (S=33.5%) taken from the Scripps Pier indicate agreement with Thorp that sound absorption below 1 kHz is about ten times greater than predicted considering only MgSO4 absorption. The low-frequency absorption which is primarily due to a multistate dissociation of boric acid is affected ...
V. P. Simmons, F. H. Fisher
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