Anechoic Chambers

During World War II Oliver C. Eckel worked with Leo Beranek at Harvard University on the construction of the first anechoic chamber built in the United States.

Since that development an evolution has taken place in the design and construction of acoustic test facilities.

Today Eckel provides the most advanced design and highest performance anechoic chambers, hemi anechoic chambers, reverberation rooms and SuperSoft free field test chambers.

Test Chamber Products

Reverberation Rooms

Eckel Reverberation rooms are designed for the determination of noise output of sound sources, transmission loss of partitions, insertion loss of silencers, response characteristics of microphones, and random incidence absorption coefficients of materials.

Eckel reverberation rooms exceed reverberant test requirements and surpass specific interior sound levels and  environmental requirements necessary for proper test measurements.

 

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Wedge and Chamber Construction

Attenuating Structures

In order to obtain a suitable sound environment, the anechoic lining is installed in a proper noise isolating structure. This enclosure may be one of several types of construction built on an isolated floor, or floated on springs or other vibration isolation material.

Masonry

A masonry enclosure is typically used in new construction, or when the anechoic facility is planned as an integral part of a new building. An 8" or 12" masonry block usually provides adequate noise reduction. The addition of an inner panel room will provide increased noise reduction when required. Walls should be constructed on an isolated reinforced floor separated from the building floor or in a pit to allow the working floor in a chamber to be flush with the host room floor.

 

 

 

 

 

Panelized Rooms

Eckel Industries, Inc. provides enclosures built from Eckoustic panels with solid faces on both sides. Eckoustic panel rooms are completely pre-fabricated in the factory and can be quickly erected in an existing facility. These modular enclosures allow for flexible arrangements of doors and utilities. Doors are structurally and acoustically compatible with the wall construction. Hard spots or internal framing are provided for attachment of hardware. Penetrations for lights, power, instrumentation wiring, and ventilation are incorporated into the panel construction. Click here to find out more about our panel rooms

 

 

Working Floors (Cable or Grating)

Since Anechoic Wedges are not designed to support heavy loads, a working floor must be provided over the top of the floor wedge points. Eckel Industries recommends two types for general use: spring tension cable floors and grating floors (expanded and subway grating). Spring tensioned cable floors are best from an acoustical standpoint, whereas floor gratings are desirable where concentrated loads must be supported. Floor gratings are provided in sections so they can be removed during testing.

Spring tensioned cable floors are best from an acoustical standpoint, whereas floor gratings are desirable where concentrated loads must be supported. Floor gratings are provided in sections so they can be removed during testing.

Entrance Doors

The Anechoic Chambers entrance sound attenuating doors can be fabricated in a variety of designs, including swing-in or swing-out hinged type, sliding-wall type, or track-riding type. Also offered is the space-saving interlocking wedge door. Here, anechoic wedges are mounted directly onto the door. When the door is swung open into the chamber, the wedge points interlock with those on the adjacent wall, minimizing the amount of lost space in the chamber.

 

 

Ventilation Design

The ventilation system in Eckel anechoic chambers is designed to maintain a uniform temperature, provide fresh air for humans and/or animals and facilitate proper combustion in air-consuming equipment. Ten to twelve air changes per hour of the free field volume will generally maintain uniform temperature and provide ample fresh air for humans or animals, while removing normal heat from lights, body radiation, and instrumentation.

Installation Procedure

Eckel anechoic linings are constructed according to a strictly supervised installation protocol. Chamber linings are installed on roll formed wedge tracks attached to wall and ceiling surfaces by means of a "Z" bar mounting system. As wedges are erected, the space between the wedges is filled with light density compressible fiberglass or melamine foam.

Instrumentation Hangers

Eckel installs all hangers and brackets required to support instrumentation and test specimens. This includes a network of all necessary cables or wires. Eckel provides engineering or design data pertinent to the support of any type of equipment within an anechoic chamber upon request of the purchasers, their consultants or engineers.

Penetration Sleeves

Electrical power, wiring, and other services are introduced into the anechoic chamber by pipe sleeves that pass through the basic structure and wedges. Eckel Industries designs pipe penetrations so that they enter the chamber through the valleys of the wedges and not the joints between the wedges.

Lighting, Electrical

Electric services are always installed in compliance with local or UL-approved regulations. Electric light, conduits, and outlets usually penetrate the structure through the wedge valleys and terminate at that point with the appropriate outlet or fixture.

Vibration Isolation

Anechoic Chambers shall be isolated from structural vibration by one of the following systems.

SuperSoft Test Chambers

Free Field Test Chambers

Picture_128Picture_121The SuperSoft compact panel chamber lining offers a practical and economic alternative for many hemi anechoic testing applications,  such as in automotive appliance components. Supersoft high performance perforated metallic modular absorber panels are installed using a track and batten system.The “V” ridged panel facings help maximize the panels performance.

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<span title=' (1) The process of dissipating sound energy. (2) The property possessed by materials, objects and structures such as rooms of absorbing sound energy. (3) A: [L2]; metric sabin---in a specified frequency band, the measure of the magnitude of the absorptive property of a material, an object, or a structure such as a room.' class='definition'>Sound Absorption</span> Report

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Super Soft Compact Panel Lining

Treatment 10 to 18 Inches

Portable Anechoic Chambers

portodudeEckel Portable Anechoic Chambers (PACs) provide the essential environment for conducting a wide variety of acoustical studies.

PACs assist in :

Improving product performance

Establishing Quality control of components and systems

Designing products with reduced noise output

Applications of these chambers include:

  • Acoustical testing and analysis of small electronic, electrical, and mechanical devices 
  • Calibration of microphones
  • Free field response testing of loudspeakers
  • Determination of hearing aid characteristics
  • Animal behavioral studies

 

Our high performance chambers are available in a broad range of sizes, with low frequency cuttoffs from 150 Hz. We offer a complete line of standardized models with various optional equipment available.

 

Features

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Outstanding Acoustic Performance

The sound attenuating enclosure is lined with pre-tested anechoic wedges, as is the access door. In addition, the floor system is non-reflective. This makes for an easily maintainable sound absorption level of between 99% and 100% inside the chamber.

Easy Installation

Standard Models are prefabricated in sections that are lined and fitted with accessories. These sections pass through a regular door, and require only bolting for final assembly and use. Units can be quickly and safely moved to any area where they are needed.

Economical

The chambers are engineered for long term operation. Acoustic and structural integrity is kept over the years.

Flexibility

Provision for external electrical connections is standard.

Construction

  • The cabinet is fabricated of 3/4" waterproof plywood reinforced with 2" x 4" external framing and 14 GA. corner steel angles for the models through 666-250-3. The larger models in the 888 series are constructed with an outside cabinet of Eckel's patented acoustic modular panels. Corners at section joints are further reinforced with steel gussets. To prevent acoustic leaks, section joints are splined.
  • Portanechoic Anechoic wedges are mounted on the interior surface of the cabinet. Wedges in low frequency cutoffs of 150, 200, and 250 Hz are available. They are constructed of fibrous glass with metal bases and have individual point protection. The wedge covering depends upon the model selected.
  • Standard doors are 25" wide by the heights of the free field, and feature heavy-duty hardware, neoprene gaskets, and hinges for 180 degrees of swing. Wedges are mounted directly on the door and swing completely clear of the opening when the door is swung through a 180 degree arc.
  • Two 1" IPS sleeves are furnished, as well as a light fixture.
  • Exterior surfaces are primed and painted with off-white enamel on wood cabinet models; metal panel cabinets.
  • The sound attenuating enclosure is lined with pre-tested anechoic wedges, as is the access door. In addition the floor system is non-reflective. This makes for an easily maintainable sound absorption level of between 99% and 100% inside the chamber. 

Wedge and Chamber Performance

Wedge Performance

A Production sample from every 100 units is tested to verify design, materials, and cut-off frequency. The test is conducted in accordance with the Impedance Tube Method- ASTM-C 384-90a. Wedges or sound absorbing elements shall have a low frequency cut-off in Hertz (Hz). Above this frequency, they shall have a coefficient of absorption value of 0.99, or a ratio of reflected sound pressure to incedent sound pressure of 10% or less.

Chamber Performance

 

 

After the full installation of the Chamer is complete, a test shall be conducted to guarantee chamber performance.

The test is conducted in accordance with ISO 3745: Inverse Square Law, ANSI 12.35 1990 (R1996). Wedges or sound absorbing elements shall have a low frequency cut-off in Hertz (Hz).

Above this frequency, they shall have a coefficient of absorption value of 0.99, or a ratio of reflected sound pressure to incedent sound pressure of 10% or less.

 

 

 

Noise Reduction, Attenuating Structures

Single Wall Panel Room

Double Wall Room

Anechoic Chamber Wedges

Eckel Anechoic Chamber linings represent the most advanced technical thinking in design and construction.

Currently we offer fiberglass, foam, and perforated metallic EMW types of sound absorbing wedges, as well as new E-Element concept and SuperSoft panels to accomodate the widest range of testing requirements.

EW Standard Wedge


The EW Standard Wedge is the classic design based on the original geometry established by Beranek and Sleeper at Harvard during World War II. Current E.W. Wedges incorporate the latest materials and design modifications for a wedge treatment with maximum broadband performance.

EMW Perforated Metalic

The Eckoustic Metallic Wedge represents the execution of the classic design with a perforated metal cover versus the original wire hardware cloth. Utilizing high transparancy 22 ga. perforated steel or aluminum, the metal cover is virtually acoustically transparent.

E-Element Anechoic Absorbing Unit

Utilizing a unique geometry, the E-Element offers a new dimension in anechoic chamber construction differing from the conventional wedge design. The E-Element is constructed of multiple parallel surfaces with tapered leading edges that alternate 90 degrees out of phase with one another. This creates a sound absorbing array which achieves cut-off with less depth of treatment than conventional "wedge" designs.
[ US Patent #5.780.785 ]

 

Acoustic Foam Wedge Unit

Acoustic Foams, (polyurethane and melamine) offer acceptable acoustical characteristics in many applications and may be more economical than traditional treatments. Polyeurathane foam chambers must incorporate a sprinkler system because they are hazardous if combusted. Properly designed foam chambers work well in many applications.


Supersoft Panel Lining

SuperSoft panel linings for acoustic test facilities were developed to fill a niche in situations where a full anechoic chamber is not required. An existing or new structure can be lined with an extremely high performance acoustic panel to yield a test environment satisfactory for general product testing and noise emission.

 




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Phone: 613.543.2967
FAX: 613.543.4173

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Phone: 617.491.3221
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