Acoustical material

Laborelec is the Belgian laboratory for the electricity industry. It deals with measuring and studying problems arising with the production, transport and distribution of electricity to industrial and private customers. It has developed very diverse domains of expertise, such as acoustics, material characteristics, technical audits to telecommunications, vibrations monitoring, etc... 

The sound-absorbing properties of acoustical materials also are influenced by the manner in which the materials are mounted. Standard mounting methods for use in laboratory testing are specified in ASTM E795-92 (2). Unless noted otherwise, pubflshed data for acoustic ceiling materials are for Mounting Type E-400, for which the material being tested is suspended 400 mm below a hard surface. 

Because the reverberation room test method approximates many real-world conditions, it is used to derive sound-absorption coefficients for evaluating the effect of most actual appHcations of sound-absorbing treatments. Sound-absorption coefficients pubflshed in acoustical textbooks and by manufacturers of acoustical materials are almost exclusively from reverberation room tests, and this may be assumed unless specified otherwise. 

Test Methodfor Impedance and Absorption of Acoustical Materials by the Impedance Tube Method, ASTM C384-90a, ASTM, Philadelphia, Pa., 1990. 

Method for Impedance and Absorption of Acoustical Materials Usinga Tube, Two Microphones, andaDigitalErequeny Analysis System, ASTME1050-90,... 

Deteriorating, damaged, or disturbed insulation, fireproofing, acoustical materials, and floor tiles... 

Most louver systems have a pitch between 30 mm and 100 mm. Where noise control is required, louvers can be supplied either in the form of acoustic louver with a pitch of 300 mm and acoustic material in the louver blade or as standard louver with an attenuator section behind it. A bird or insect guard (as applicable) is normally mounted behind the louver. 

Asbestos from draperies, filters, stove mats, floor tUes, spackling compounds, older furnaces, roofing, gaskets, insulation, acoustical material, pipes, etc. ... 

Cox, B. N. and Addison, R. C. (1984). Modelling the acoustic material signature in the presence of a surface-breaking crack. In Review of progress in quantitative nondestructive evaluation (ed. D. O. Thompson and D. E. Chimenti), pp. 1173-84. Plenum Press, New York. [271]... 

Weglein, R. D. (1979a). A model for predicting acoustic materials signatures. Appl. 

Wi.h the increase in knowledge in the field of acoustics and the awareness of the need for the control of sound, various acoustical products have appeared for employment by the public. This paper covers architectural acoustical materials only. The architectural acoustical products now on the market can be divided into two general classes, the inorganic and the organic type of product. 

Figure 8. Master Curves of PYC Acoustical Material Multiplex DMA Data RepresentecJ on Reciuced Frequency Nomograph. Enlargement of Area A in Figure 7. "Universal" WLF Equation.

Table 2 shows the effect that changing the form of the WLF equation has on the calculated peak temperature values for 1000 Hz. In addition, it compares those values calculated from the different WLF constants with the corresponding values calculated from the Arrhenius equation. All data are for the PVC acoustical material. 

ASTM C 384 is another method used for acoustical materials. This method is an impedance-tube method. In the test a flexible-foam specimen is placed in a cavity over a vacuum chamber. A specified constant-air-pressure differential is then created. The air-flow value is the rate of flow of air required to maintain this pressure differential. The test is carried out 1) with air flow parallel to foam rise, and 2) with air flow perpendicular to foam rise. Air-flow values are proportional to porosity in flexible foams. 

ASTM C 522-87 Standard Test Method for Airflow Resistance Of Acoustical Materials, 5 pp (Comm E-33)... 

The Acoustical Materials Associations of New York collects monthly sales data on acoustical materials for its membership. 

Data on acoustical materials sales, monthly annual technical publications. 

Sound transmission loss ratio of the sound energy emitted by an acoustical material or structure to the energy incident upon the opposite side. 

Safari A, Akdogan EK. Piezoelectric and acoustic materials for transducer applications. Springer Science and Business Media. Springer US 2008. http //link.springer.com/book/ 10.1007%2F978-0-387-76540-2. 

When sound waves come in contact with a boundary obstacle, such as a wall or door, a portion of the sound wave energy is reflected, a portion is transmitted through the obstacle, and the rest is absorbed by the obstacle. One of the standard methods of measuring the effective sound absorption coefficient of an acoustical material is by finding its effect on the reverberation time, or decay rate, of the sound pressure level in the sound chamber. The total sound absorption in the receiving room is required to determine the noise reduction of the specimen being tested. The key here is to rule out the absorption of sound waves within the chamber that may be attributed to the door being tested. 

Acoustical material n. Any material considered in terms of its acoustical properties. Commonly and especially, a material designed to absorb sound. 

Acoustical tile n. An acoustical material in board form, usually having unit dimensions of 24 in. X 24 in. (approx. 61cm X 61 cm) or less. Usually used on ceilings but also may be applied to sidewalls. Harris CM (2005) Dictionary of architecture and construction. McGraw-Hill Co., New York. 

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