Fully Anechoic Chamber

The Fully Anechoic Room is designed to meet the needs of physicists and engineers who require precise sound measurements in a free-field acoustic environment. This type of room provides high sound transmission loss (TL) performance and is fully lined with anechoic wedges to ensure complete sound absorption and compliance with acoustic standards.

For maximum sound isolation, the room is constructed in a room within a room configuration, utilizing certified components and mounted on a vibration isolation system specifically designed according to the rooms weight and frequency cut-off requirements.

These chambers are designed for applications and locations where the noise reduction characteristics for a single wall and ceiling construction provide adequate noise isolation.

The single wall construction results in smaller overall outside dimensions and is particularly suited to placement in less noisy areas. In every other respect, they are similar to the Hemi-anechoic chambers with the same standard features and options available.

Standard Features

Fully Anechoic rooms come with the following standard features:

• Anechoic wedges made from foam or fiberglass, designed to achieve the required low-frequency cut-off.
• Single or double wall and ceiling construction using acoustic panels.
• Standard ventilation system connected to the buildings air supply.
• Circular cable ports
• Interior non-reflective cable floor system above the floor wedges with a nylon catch net below
• IAC Acousti-flote floor system with vibration isolators
• One IAC Noise-lock® wedge acoustic door

Options

Floor grating for chambers which will house heavy items Additional or larger Noise-lock® acoustic doors Access panels for equipment and test openings Double Acousti-flote floor for anechoic rooms Air mounts, springs or other types of vibration isolators Independent ventilation system

Floors

Anechoic chambers present a design challenge when personnel need to enter the facility to place test objects or equipment while maintaining minimal sound reflection.

Various floor solutions have been developed to minimize reflective sound, with typical installations utilizing a grid-based floor system to enhance the absorption efficiency of the floor wedges. Additionally, cable floor systems are used to safely support personnel and heavy test equipment within the chamber.

For facilities requiring the highest level of precision, retractable floor systems are available. These systems can completely remove any reflective surfaces during operation, ensuring the most accurate and reliable acoustic measurements.

Cable Floors

Fully Anechoic chambers are typically provided with a tensioned cable floor, situated approximately four inches above the tips of the floor wedges. Beneath this cable floor we fit an acoustically transparent nylon catch net to prevent debris and small objects falling out of reach.

The cable floor consists of stainless steel cable interwoven in a criss-cross matrix of 50mm separation. Each cable is tensioned from an acoustically lagged steel ring beam by turnbuckles at one end and a coil spring at the other. This ensures that the floor is strong with even deformation and spring characteristics.

Typical uses of high precision anechoic and hemi-anechoic chambers include

Microphone Calibration

• Primary calibration, free-field reciprocity method
• Secondary calibration by the substitution method
• Frequency response and directivity Sound Level Meter Calibration
• Pattern evaluation
• Frequency response
• Directivity

Speaker Research & Development

• Sound power output measurements
• Physical speaker design
• Distortion and frequency response

Acoustic Science

• PhD projects
• Ultrasound scanning research
• Virtual acoustics generating auralisations of concert halls, city streets and other spaces

CE Marking / Certification

• All machines are required to have a sound power output test carried out prior to being released for sale
• Testing of toys to ensure suitability for hearing in children
• Items such as hearing protectors are required to be tested in an anechoic chamber to measure their effectiveness

Hearing Research

• Free-field audiometry
• Cochlear implant testing

Psycho-acoustic Testing

• Sound perception testing is typically used for research and development of products
• An example of research carried out was by Stable Micro Systems Ltd at NPL in the UK where tests were carried out on the crispiness of biscuits and their effects of peoples perceptions of taste