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  2. Anechoic chamber - Wikipedia

    en.wikipedia.org/wiki/Anechoic_chamber

    In general, the interior of an anechoic chamber can be very quiet, with typical noise levels in the 10–20 dBA range. In 2005, the best anechoic chamber measured at −9.4 dBA. [2] In 2015, an anechoic chamber on the campus of Microsoft broke the world record with a measurement of −20.6 dBA. [3]

  3. Loudspeaker measurement - Wikipedia

    en.wikipedia.org/wiki/Loudspeaker_measurement

    A tetrahedral test chamber. A tetrahedral chamber is capable of measuring the low frequency limit of the driver without the large footprint required by an anechoic chamber. This compact measurement system for loudspeaker drivers is defined in IEC 60268-21:2018, [1] IEC 60268-22:2020 [2] and AES73id-2019. [3]

  4. Antenna measurement - Wikipedia

    en.wikipedia.org/wiki/Antenna_measurement

    The size of the range that is required can be much less than the size required for a full-size far-field anechoic chamber, although the cost of fabrication of the specially-designed CATR reflector can be expensive due to the need to ensure precision of the reflecting surface (typically less than ⁠ 1 / 100 ⁠ λ RMS surface accuracy) and to ...

  5. Radiation-absorbent material - Wikipedia

    en.wikipedia.org/wiki/Radiation-absorbent_material

    For low-frequency damping in military applications, this distance is often 60 cm (24 in), while high-frequency panels are as short as 7.5 to 10 cm (3 to 4 in). An example of a high-frequency application would be the police radar (speed-measuring radar K and Ka band), the pyramids would have a dimension around 10 cm (4 in) long and a 5 cm × 5 ...

  6. Absorption (acoustics) - Wikipedia

    en.wikipedia.org/wiki/Absorption_(acoustics)

    An acoustic anechoic chamber is a room designed to absorb as much sound as possible. The walls consist of a number of baffles with highly absorptive material arranged in such a way that the fraction of sound they do reflect is directed towards another baffle instead of back into the room.

  7. Plane wave tube - Wikipedia

    en.wikipedia.org/wiki/Plane_wave_tube

    Anechoic chambers are typically subject to a low frequency limit, governed by the length of the sound absorbing wedges employed to prevent reflections within the chamber. Test and measurement microphone calibration services are often required to be undertaken at frequencies where anechoic chambers cannot be used effectively. In this case, a ...

  8. Reference antenna - Wikipedia

    en.wikipedia.org/wiki/Reference_antenna

    In a common usage scenario a reference antenna would be used as a transfer standard. First the reference antenna's performance is measured using high accuracy measurement facility. This test may be done using an electromagnetic anechoic chamber or another type of antenna test range (see Antenna measurements). The antenna is then measured using ...

  9. Loudspeaker acoustics - Wikipedia

    en.wikipedia.org/wiki/Loudspeaker_acoustics

    Listening to sound in an anechoic "dead" room is quite different from listening in a conventional room, and, while revealing about loudspeaker behaviour it has an unnatural sonic character that some listeners find uncomfortable. Conventional stereo reproduction is more natural if the listening environment has some acoustically reflective surfaces.