Allied International Corporation, specializing in acoustic attenuation, has been serving customers in the United States, Europe, and the Far East for over 50 years.

The Acoustic Division offers a complete line of acoustic products and services to help our customers solve the most demanding noise problems.

Shipping / Naval
High Speed Rail
Locomotive
Trucking
Automobile
Motorcycle
All Terrain Vehicle
Construction Equipment
Mining Equipment

• Measurement and analysis of noise source
• Isolation and identification of sources
• Treatment recommendations based on requirements of noise spectra,
operating environment, weight, material costs, etc.
• Design and production of prototypes
• Production of completed assemblies and subassemblies
• Installation of materials
• Testing and consulting

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ALLIED INTERNATIONAL ADVANTAGES

The Marketing and Engineering staff at Allied International has over 100 years of combined experience designing, manufacturing, and selling acoustic materials and assemblies.

We offer a full complement of acoustic products and services, and strive to supply highly effective solutions at the lowest possible cost.

We specialize in difficult applications where heat, corrosion, size, and weight are primary concerns.

Using Allied International as your noise control solution provider offers the following advantages:

Metal fiber silencers all use the same treatment concept. The duct walls are made of porous metal that is supported by a spacing arrangement from a solid wall. The duct cross sectional dimensions, the fiber metal, and the depth of this spacing arrangement constitute a tuned system that is broadly effective in a desired frequency band. The overall effectiveness of the treatment depends on this tuning and the surface area of the duct that is treated. The treatment may be varied in different areas of the duct to broaden the overall tuning.

In tuning the duct liner, fiber metal is particularly effective for those frequencies that have standing wavelengths () that match the duct cross sectional dimensions. The fiber metal is placed at the position of the maximum particle velocity of the standing wave. Friction from the movement of molecules through the porous material will convert sound energy to heat thereby reducing sound intensity. This reduction is highest if the porous material is placed where the air molecular movement is at a maximum.

The absorption of sound by fiber metal is greatest when its acoustical impedance (flow resistance) matches the impedance of air in the duct. If the impedance is too high, the material reflects the sound wave, as would a solid wall. If it is too low the sound wave freely travels through the material. In either case the sound attenuation is lower than maximum. When properly specified, the normal incidence absorption coefficient for fiber metal acoustic media is typically in the range of 0.80 to 0.95, with 1.00 being an ideal absorber.