New pressure-field microphone from Brüel & Kjær

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Brüel & Kjær’s latest miniature microphone helps acoustic engineers record accurate  measurements in pressurized-field applications such as with couplers. The 0.25in low-noise microphone is also useful as a general measuring device at different angles of incidence, or for monitoring noise near audio device sound ports. Developing instruments of this kind is essential for the automotive industry because predicting and monitoring sounds and vibrations enables manufacturers to control tire rumble, wind noise in the cabin, and the acoustic properties of in-car infotainment systems.

The all-titanium construction Type 4988-A mic has a laser-welded diaphragm and operates in the frequency range from 20 to 20,000Hz. It has a dynamic range of 29dB(A) to 146dB and is paired with a constant-current line-drive (CCLD) preamplifier. The corrosion-resistant unit is also suitable for acoustic testing in strong magnetic fields. It is said to have excellent stability in temperatures from -20 to 80°C and all humidity levels, plus minimal spread in frequency response between units.

The Type 4988-A is particularly useful for taking measurements in acoustic chambers and test boxes where reflections occur, as well as in unpredictable sound field conditions, in testing systems, and as a reference microphone for tuning larger arrays with active noise-cancelling systems.

Dr Rémi Guastavino, Brüel & Kjær’s acoustic domain specialist, said, “The Type 4988-A is the perfect microphone to be used in the automotive industry. Its small size allows it to fit nearly anywhere in the cabin; the all-titanium construction enables it to be used near electric motors producing strong magnetic fields; and the flatness of its frequency response – all microphones are flat ±1dB – saves the user time because they do not need to make corrections for each individual microphone.”

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Liam is a freelance writer and sub-editor for The Daily Telegraph. He has written 70 books on subjects ranging from the history of Ferrari and Formula 1 to the world’s most famous TV cars. He has edited another 40 books, including the Discarded Science series by Hugo Award-winning author John Grant. He is also the author of eight screenplays, two of which are now in pre-production.

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