Acoustics - Measurement of sound absorption properties of road surfaces in situ

Conventional polyurethane foam has non-tunable sound absorption properties. Here, a magneto-induced foam, called magnetorheological (MR) foam, was fabricated with the feature of being able to tune sound absorption properties, primarily from the middle- to higher-frequency ranges. Three different samples of MR foams were fabricated in situ by varying the concentration of Carbonyl Iron Particles (CIPs) (0, 35, and 75 wt.%). The magnetization properties and tunable sound absorption characteristics were evaluated. From the magnetic saturation properties, the results showed very narrow and small coercivity of hysteresis loops relative to the soft magnetic properties of the CIPs. MR foam with 75 wt.% CIPs showed a higher magnetic saturation at 91.350 emu/g compared to MR foam with 35 wt.% CIPs at 63.896 emu/g. For tunable sound absorption testing, the effect of ‘shifting’ to higher frequency was also observed when the magnetic field was applied, which was ~10 Hz for MR foam with 35 wt.% CIPs and ~130 Hz for MR foam with 75 wt.% CIPs. As the latest evolution of semi-active noise control materials, the results from this study are valuable guidance for the advancement of MR-based devices.

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Investigation of Acoustic Properties of Different Types of Low-Noise Road Surfacers under In Situ and Laboratory Conditions

Materials ◽

10.3390/ma15020480 ◽

2022 ◽

Vol 15 (2) ◽

pp. 480

Author(s):

Janusz Bohatkiewicz ◽

Maciej Hałucha ◽

Marcin Kamil Dębiński ◽

Michał Jukowski ◽

Zbigniew Tabor

Keyword(s):

Sound Absorption ◽

Low Noise ◽

Operating Conditions ◽

Acoustic Properties ◽

Road Noise ◽

In Situ Conditions ◽

Study Results ◽

Road Surfaces ◽

Impedance Tube Method

Current literature on the performance characteristics of road surfaces is primarily focused on evenness, roughness and technical durability. However, other important surface properties require analysis, including noisiness, which is an important feature of the environmental impact of vehicular traffic around roads. This can be studied using various methods by which road noise phenomena are investigated. The method used to measure the noise performance of road surfaces herein is the Statistical Pass-By (SPB) method, as described in ISO 11819-1:1997. The impedance tube method was used for sound absorption testing, as described in ISO 13472-2:2010. These tests were performed under a variety of conditions: in situ and in laboratory. The existence of relationships between them can be helpful in selecting surfaces for noise reduction. Preliminary surface noise tests can be performed in the laboratory with samples consisting of various compounds. This is less expensive and faster than doing so on purpose-built surfaces. The paper presents study results for sound absorption coefficients of various types of low-noise surfaces in in situ conditions (on an experimental section and on operated road sections) and in the laboratory setting. The results of the tests performed on the operational sections were compared to the results of the surface impact on road noise using the SPB method. The correlations between the test results help confirm the feasibility of road surface pre-testing in the laboratory and the relation to tests performed using the SPB method under typical operating conditions.

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Preparation of natural bio-based Eucommia ulmoides gum/styrene-butadiene rubber composites and the evaluation of their damping and sound absorption properties

Polymer ◽

10.1016/j.polymer.2020.123292 ◽

2021 ◽

Vol 213 ◽

pp. 123292

Author(s):

Renwei Cao ◽

Linhui Deng ◽

Zhibo Feng ◽

Xiuying Zhao ◽

Xiaolin Li ◽

...

Keyword(s):

Sound Absorption ◽

Styrene Butadiene Rubber ◽

Eucommia Ulmoides ◽

Butadiene Rubber ◽

Rubber Composites ◽

Absorption Properties ◽

Eucommia Ulmoides Gum ◽

Styrene Butadiene

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Acoustic Panels Made of Paper Sludge and Clay Composites

Sustainability ◽

10.3390/su13020637 ◽

2021 ◽

Vol 13 (2) ◽

pp. 637

Author(s):

Tomas Astrauskas ◽

Tomas Januševičius ◽

Raimondas Grubliauskas

Keyword(s):

Absorption Coefficient ◽

Sound Absorption ◽

Composite Panel ◽

Sound Absorption Coefficient ◽

Core Material ◽

Paper Sludge ◽

Frequency Range ◽

Absorption Properties ◽

Air Gaps ◽

The Core

Studies on recycled materials emerged during recent years. This paper investigates samples’ sound absorption properties for panels fabricated of a mixture of paper sludge (PS) and clay mixture. PS was the core material. The sound absorption was measured. We also consider the influence of an air gap between panels and rigid backing. Different air gaps (50, 100, 150, 200 mm) simulate existing acoustic panel systems. Finally, the PS and clay composite panel sound absorption coefficients are compared to those for a typical commercial absorptive ceiling panel. The average sound absorption coefficient of PS-clay composite panels (αavg. in the frequency range from 250 to 1600 Hz) was up to 0.55. The resulting average sound absorption coefficient of panels made of recycled (but unfinished) materials is even somewhat higher than for the finished commercial (finished) acoustic panel (αavg. = 0.51).

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