Brüel & Kjær Sound & Vibration Measurement A/S


Bruel & Kjaer (B&K) introduces new, state-of-the-art models in its range of measuring microphones and related equipment for the measurement of sound in the latest version of its Microphones & Conditioning Product Catalogue.

In response to customer requests, the 2007 catalogue includes connection charts for the extended ranges of microphones (diffuse-field, pressure-field, low-noise), amplifiers, cables and power-supplies. It also includes information about acoustical, regulatory and related standards, plus a glossary of acoustical terms.

New to this version are articles about different branches of acoustical measurement and selecting the right microphone for individual applications. It outlines the operating principles of current microphone technologies, signal conditioning equipment, power supplies and calibration equipment.

As both a long-time pioneer and continuing innovator of sound measurement Bruel & Kjaer includes modern equivalents to old or discontinued models as well as new models such as the Type 4955 low-noise microphone in the new catalogue.

The catalogue also provides information about the services Bruel & Kjaer provides to maintain end-users' equipment and to ensure acoustical measurement integrity through the entire lifetime of the products.

Type 2699 A-weighted Deltatron pre-amplifier has two engraved rings
The Type 2699 combines a Deltatron preamplifier and an A-weighting filter in one unit. This is useful for in-car measurements in the presence of large low-frequency components. The fact that A-weighting is applied is contained in the Type 2699’s Transducer Electronic Datasheet (TEDS) and the two rings engraved on its shell visibly differentiate the Type 2699 from other pre-amplifiers without A-weighting to eliminate testing errors.

New free-field microphones
Free-field microphones are particularly suitable for making measurements away from reflecting surfaces, for example, when making outdoor measurements with a sound level meter, or in an anechoic chamber or other acoustically well-damped indoor environments.

Three new free-field microphones are being introduced:
Type 4955 1/2' low-noise microphone & pre-amplifier is a 1/2' all titanium TEDS microphone with a guaranteed noise-floor less than 6.5 dB(A). It is optimised for sound power measurements to ISO 3745 and for characterising the noise floor of anechoic chambers.

Type 4950 1/2' pre-polarised free-field for 2250 light conforms to standards IEC 61672 Class 1 and ANSI S1.4 Type 1. Its optimised frequency response (±2dB) is 4 to 16 kHz, and its dynamic range (with pre-amplifier type 2669) is 14 to 142 dB(A).

Types 4954 & 4954A 1/4' pre-polarised free-field microphones conform to standards IEC 61094 - 4 WS3F. Its optimised frequency response (±2dB) is 4 to 80 kHz, and its dynamic range (with pre-amplifier type 2670) is 40 to 164 dB(A). Type 4954A has an integral Deltatron preamplifier and is identical to type 4954 in all other respects.

New Array microphone and cable
Array applications are gaining popularity for noise source identification. Types 4957 and 4958 are high sensitivity array microphones and feature an integral DeltaTron pre-amplifier. Each microphone ‘s amplitude and phase corrections are individually measured and stored in the Transducer Electronic Datasheet (TEDS). When used with a measurement system that supports amplitude and phase correction, noise source identification can be made with greater precision.

4957 1/4' Array microphone 17mV/Pa 50 to 10kHz: The 4957 1/4' Array microphone: Nominal sensitivity 17mV/Pa, optimised frequency response (±2dB) 50 to 10kHz.

Type 4958 1/4' Array microphone 17mV/Pa 20 to 20kHz: The specification of the 4958 is identical that of the 4957, but has a different optimised frequency response (±2dB) 20 to 20kHz.

Free web seminars
Bruel & Kjaer offers free sound and vibration online training. Forthcoming topics include: News In Automotive Testing, Calibration Of Microphones, Accelerometers and Sound-Level Meters, Checking NHV Variability Of Production Vehicles Using 2250 Hand-Held Analyser, Fundamentals Of Measuring Sound, and Accelerometer Mounting Techniques. For further information about free web seminars visit

For further information please contact Heather Wilkins, Marketing Coordinator, Bruel & Kjaer UK Limited, Bedford House, Rutherford Close, Stevenage, Herts SG1 2ND. Telephone: 01438 739000. Fax: 01438 739099. Email: Web site:

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