Acoustic chamber – how does it work and where to use it?

In the world of sound engineering and acoustic design, the term “acoustic chamber” often sparks curiosity. These specialized spaces are pivotal in analyzing sound waves’ behaviour, optimizing noise levels, or enhancing sound quality of products. But what exactly is an acoustic chamber, and how does it function? Understanding its purpose and practical applications is essential for anyone delving into the realm of audio technology or seeking to optimize sound environments. Join us as we explore the intricacies of acoustic chambers, and uncovering the diverse scenarios where they prove indispensable.

What is an acoustic chamber and what is it used for?

Acoustic chambers serve as essential tools in acoustics, offering a controlled environment for experiments conducted in “free field” conditions. Here, sound waves encounter minimal interference, ensuring accurate assessments. Such chambers come in several variants. They are anechoic and then offer "free field conditions", or not fully anechoic (semi-anechoic) and then "free field over reflecting plane" conditions, or reverberant – then they offer “diffuse field conditions”.

The principle of functionality of the acoustic chamber

Upon entering entering anechoic or semi-anechoic chamber, one encounters a landscape full of long triangular foam wedges covering surfaces. These meticulously designed wedges serve as a proof against sound reverberation, preventing unwanted reflections and maintaining clear acoustic conditions within the chamber.

Reverberation chambers on the other hand, are covered with a smooth surface, most often made of concrete, which ensures efficient reflection of sound in all directions.

Key structural elements of the acoustic chamber

Regardless of chamber type, certain design principles must be upheld to ensure optimal functionality. Mechanical, electrical, acoustical, and aerodynamic considerations govern the chamber’s dimensions, internal measurements, ambient noise levels, ventilation, and surface treatments.

Usually, anechoic chamber comes with the following standard features:

• Anechoic wedges, made of foam and fabric,
• Double or single wall and ceiling acoustic panel construction,
• Ventilation system meeting the acoustical backgrund noise requiremnts for the dedicated measurements,
• Acoustically non reflective interior lighting,
• Interior non-reflective cable floor system,
• Wedge acoustic door.

Types of acoustic chambers and their specific applications

One type of an acoustic chamber is the anechoic chamber. This type of space is commonly used in acoustics to conduct experiments in “free field” conditions, free-field meaning that there are no reflected waves. These acoustic chambers are constructed with the interior surfaces lined with anechoic wedges providing up to 100% absorption of the incident sound energy, making them echo-free.
Another type of an acoustic chamber is a reverberation room. It is designed so that the walls, floor and ceiling reflect almost all the sound back into the room. It is the opposite of an anechoic chamber and is used for different types of acoustical testing.

How to use an acoustic chamber in scientific research?

Acoustic chambers find extensive utility in scientific research, enabling the characterization of noise sources and acoustic properties of products and materials. These chambers facilitate acoustical experiments demanding clear free-field conditions Access to various chambers enables comprehensive acoustic research. Scientific units often do not have access to many types of chambers at the same time. If they have specific research and needs to perform, or if a given manufacturer needs to examine the product comprehensively, they establish cooperation with other organizations. An example of an organization that can support both scientific units and companies is KFB’s ARIC, which is ideal for this purpose because it has a set of experimental and research stations for conducting acoustic tests.

We use acoustic chambers to measure, assess and optimize acoustical properties of machines and devices, mainly:

• The noise of construction machinery
• The noise of the ventilation components
• Sound design
• Acoustic and vibroacoustic properties of materials, products and components
• Virtual prototyping
• Vibration tests
• Psychoacoustics

Reverberation chambers, on the other hands are used mostly for building acoustics, namely:

• Acoustic properties of materials and products
• Building acoustics
• Interior acoustics
• Virtual prototyping
• Psychoacoustics in construction

Practical use of the acoustic chamber in various industries

Industries reliant on precise acoustic testing and analysis benefit immensely from acoustic chambers. Facilities equipped with acoustic chambers can conduct a product development in the field of acoustics. It is an ideal environment for predicting and designing the sound output of various types of products, such as household appliances, ventilation installations and most importantly, all devices whose operation is based on rotary elements.

Automotive manufacturers leverage these chambers to scrutinize vehicle components’ noise levels and acoustic performances, ensuring compliance with rigorous standards before market release. Likewise, entities involved in noise control product manufacturing and regulatory compliance rely on acoustic chambers to uphold stringent acoustic standards.

Another industry, where understanding acoustic plays crucial role for its functionality is construction. Attenuating the external noise caused by the ever-increasing number of sources, like traffic or industry noise in urban areas, requires understanding of the behavior of sound in the room in order to adapt its structure accordingly and select proper building elements. Determining the Airborne Sound Insulation of building elements (windows, doors, walls, boards, façades, etc.) and between rooms is of primary importance for the manufacturers in the industry, as it offers an objective evaluation of the acoustic performance of their products.

Acoustic chamber in audio product design

Acoustic chambers emerge as indispensable assets in audio product design endeavors. Audio product design refers to the design of audio equipment – e.g. speakers, microphones. Such elements are tested in chambers, e.g. before being released on the market – an anechoic chamber is then used. Measurements in the chamber enable, for example, the determination of some parameters mentioned in the technical specifications of speakers or microphones. Facilitating sound quality assessments, noise reduction testing, and reverberation analyses, these chambers allow engineers to craft high-fidelity audio solutions tailored to consumers’
discerning preferences.

The role of the acoustic chamber in testing insulating materials

The role of acoustic chambers extends to evaluating the efficacy of insulating materials in attenuating sound transmission. Through sound transmission loss testing, frequency-specific analyses, and standardized procedures, engineers discern the insulating materials’ performance across diverse applications, ranging from building construction to automotive interiors.

In essence, acoustic chambers stand as testing grounds for sound experimentation, offering invaluable insights into acoustic phenomena and facilitating innovations across diverse industries.

Why is an acoustic chamber necessary in acoustics?

Acoustic chambers stand as indispensable tools in various fields of acousticsacoustics due to their ability to provide controlled environments for precise sound experimentation. By offering echo-free spaces and enabling accurate assessments of sound properties, these chambers facilitate rigorous testing, research, and product development across various industries. From evaluating sound insulation materials to fine-tuning audio equipment, acoustic chambers serve as pillars of innovation, driving advancements in acoustical science and engineering.

Acoustic chamber – where can one find it?

Acoustic chambers are integral components of research institutions, universities, engineering firms, and specialized testing facilities worldwide. These chambers are commonly housed within acoustics laboratories, audio engineering departments, and industries requiring precise acoustic testing capabilities. Additionally, automotive manufacturers, aerospace companies, and organizations focused on noise control and product development often feature dedicated
acoustic chambers within their facilities. The perfect example of a testing facility developed by an engineering company is ARIC (Acoustic Research and Innovation Center) in Wrocław. The facility, established by KFB Acoustics develops opportunities for acoustic technologies in industry and environment.