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Ideal Microphone for Unpredictable Sound Fields

30 June 2009

New Brüel & Kjær microphone ensures accurate measurements in free, diffuse and multi-field conditions

Brüel & Kjær has launched the world’s first multi-field measuring microphone - a unique ¼” transducer with the same low noise floor as a ½” microphone. The 4961 multi-field microphone is the only ¼” measuring microphone in the world with a 20 dB(A) noise floor and sensitivity exceeding 60 mV/Pa – enabling it to take accurate measurements in free, diffuse or diverse sound fields. With its small design, the 4961 model is relatively insensitive to the angle of sound incidence, so it simplifies the process of making complex sound measurements and saves technicians valuable time during planning, set up and analysis of measurements. With its optimised multi-field response, the 4961 multi-field microphone produces accurate measurements, in a wide range of sound field conditions, making it ideal for situations where the nature of the sound field is unknown - or could change over time. It is also well-suited to complex spaces with non-stationary or multiple sources that need to be measured in one go. In effect, a single multi-field microphone can cover many measuring scenarios that would otherwise require more than one conventional ½” microphone. Typical applications areas include aircraft or vehicle cabins, and near-field measurements such as around engines - in fact, any situation where sound can arrive at the microphone from many different directions. As with all Brüel & Kjær measuring microphones the 4961 models have been assembled in a clean room, which ensures that the microphones maintain their inherent low noise and high stability, even in environments where humidity and temperature are high. With all-titanium construction, which guarantees maximum resistance to corrosion without any risk of interference from magnetic fields, the Type 4961 multi-field microphone is built to the same high levels of quality, robustness and reliability that have become the hallmarks of all microphones from Brüel & Kjær. “Quite often the wrong microphone for a measurement task is picked due to the user’s lack of knowledge or a lack of equipment availability,” said Bruel & Kjaer UK Managing Director, William Egan. “Sound measurements vary greatly depending on the environment in which the tests are performed and the noise sources themselves affect the type of microphones to be used. The engineer would have to gauge the nature of the sound field – is it free field, diffuse or a mixture of both - to determine what type of microphone is most suitable. With a multi field microphone this is no longer necessary.”

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Bruel & Kjaer UK