Anechoic chamber

When testing microphones (and speakers), precise control of the acoustic environment is essential to obtain accurate and reliable measurement data. Uncontrolled reflections from surfaces and ambient noise can interfere with the measurements, leading to erroneous conclusions.

In an anechoic chamber, the walls, floor, and ceiling are lined with acoustic wedges designed to absorb soundwaves and eliminate reflections that would otherwise distort the test results. This ensures that the microphone captures only the direct sound produced by the speaker. Any imperfections in the speaker’s linearity are corrected using a calibrated reference microphone, positioned adjacent to the microphone under test, providing a comparative baseline for the measurements.

Additionally, the ambient SPL (background noise) within the test chamber should be lower than the microphone’s self-noise level to achieve accurate noise floor measurements. Milab’s chamber is exceptionally quiet; in fact, the ambient SPL is below the threshold of human hearing across the entire audible frequency range (see chart).

Note that the ambient SPL for frequency ranges 31.5 HZ – 50 Hz, 125 Hz – 250 Hz and 800 Hz – 12.5 kHz were equal to the noise floor of the measurement system, and therefore, for these frequencies, the ambient SPL is likely even lower than reported here.

At Milab, we have utilized anechoic chambers for decades, but when constructing our new facility in Helsingborg, we commissioned IAC Acoustics to design and build a state-of-the-art chamber specifically tailored to meet all of our requirements. IAC is a highly respected supplier of anechoic chambers, with clients that include BBC, Dolby, NASA, and many others.

The chamber is equipped with an NTI FX100 Audio Analyzer, providing comprehensive testing capabilities for audio measurements.

Click here for an immersive 360° look inside the chamber.

When not in use, we may offer the chamber for rental to external parties requiring precise acoustic testing. For more information, or to inquire about availability, please contact us. More detailed technical documentation on the performance and specifications of the chamber and test system is available upon request.