Anechoic & Hemi-Anechoic Chambers

Noise control rooms and chambers used for acoustic testing of components and manufactured systems.

An Anechoic Chamber is a specialized room designed to minimize or eliminate sound reflections. It is constructed with materials that absorb sound waves and minimize any interference or reverberation, creating an environment with extremely low levels of sound wave reflection.

Here are a few considerations regarding Anechoic Chambers:

Sound Absorption: Anechoic chambers are lined with sound-absorbing materials on the walls, ceiling, and floor. These materials typically consist of wedges, foam, or fiberglass elements that absorb sound waves and minimize their reflection back into the chamber.

Isolation: Anechoic chambers are built to provide isolation from external noise and vibrations. The walls are often constructed using multiple layers of materials with high sound isolation properties to block out
Floating Floor: A floating floor system is commonly used in anechoic chambers to further isolate the chamber from external vibrations. This helps minimize any unwanted vibrations that could interfere with precise measurements or experiments.

Echo-Free Design: The internal design of an anechoic chamber is carefully engineered to minimize any internal reflections. Special attention is given to avoiding parallel surfaces, which can cause unwanted sound reflections and create standing waves.

Testing and Research: Anechoic chambers are primarily used for acoustic or electromagnetic testing and research. They provide a controlled environment with minimal external interference, allowing for precise measurements and analysis of sound or electromagnetic properties.

Reverberation Time: A well-designed anechoic chamber aims to achieve a very low reverberation time. In an ideal anechoic chamber, the reverberation time is extremely short, typically in the order of milliseconds.
Anechoic chambers are commonly used in various fields such as acoustics, audio engineering, telecommunications and product development.

A Hemi-Anechoic chamber is a specialized testing environment that combines elements of both an anechoic chamber and a normal room. It incorporates sound-absorbing materials on the walls, and ceiling to minimize sound reflections. The goal is to create a highly absorbent environment to minimize reflections and echoes at less cost and complexity than a fully Anechoic Chamber.

Unlike an anechoic chamber, a hemi-anechoic chamber includes a reflective floor or ground plane. Therefore, no acoustic treatment is usually required on the floor. While still providing a good acoustic test environment, it eliminates the need for a ‘floating floor’, and simplifies access to the device under test and any necessary instrumentation. Sound reflections from the floor can be accounted for in the testing process.

Noise Test Booths or “Acoustic Test Rooms” are typically far less expensive than Anechoic or Hemi-Anechoic facilities, and are intended for non-laboratory testing of sound levels, typically in a production environment where precision measurements are not required. They can provide excellent attenuation of background noise and still be used (within limited frequency ranges) for product qualification or end-of-line noise tests.

MEMTECH has extensive experience in the evaluation, design and construction of anechoic, hemi-anechoic and acoustic isolation booths used for testing of components and manufactured systems. We also perform baseline evaluations of current acoustic test facilities to evaluate performance, and to make necessary improvements to meet ever-changing specifications and noise criteria.

We offer a variety of technical and support services to support your acoustic testing needs, including optimizing reverberation times and sound transmission loss. We can also engineer cost-effective solutions to reduce coupled-floor or other structural vibration sources, or to eliminate noise “leakage” into the room. Whether it’s an NVH cell, Anechoic/Hemi-Anechoic Test Chamber, or Noise Containment Enclosures, Memtech Acoustical will work with our customers from the initial noise study through the final construction and validation.