Fully Anechoic Chambers

The IAC Acoustics fully anechoic room is designed for the research physicist or engineer who must make precise sound measurements in a free-field acoustic environment. rooms provide high sound transmission loss (TL) characteristics and have a completely anechoic wedge lined interior to meet these requirements.

For maximum sound isolation, our rooms are designed as a room within a room featuring certified IAC Noise-lock® and Moduline™ components. The inner room is set on a vibration isolation system created for the specific weight and frequency cut-off of the room.

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 (foam, fibreglass or IAC Metadyne®) with the required low-frequency cut-offs
  • Double or single wall and ceiling acoustic panel construction
  • IAC Acoustics standard ventilation system coupled to the building supply
  • Lighting (interior) minimally acoustically reflective
  • 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 pose a challenge when people need to enter the facility in order to place items under test. IAC Acoustics has developed a range of floor solutions to minimize reflective sound. Typical installations ultilize a grid-based system to maximize the absorption of the floor wedges. We also use a range of cable floors to support people and heavy test objects. For some very high specification facilities, we have even developed a range of retractable floors which completely remove any reflective surfaces when in use to achieve the most accurate 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

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

Acoustic Science

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

Hearing Research

  • Free-field audiometry
  • Cochlear implant testing

Sensory Deprivation Testing

  • Used for military and educational research

Speaker Research & Development

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

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

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

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