Catalogue expands microphone coverage

Edited by the Engineeringtalk editorial team Apr 16, 2007

Microphones and conditioning product catalogue includes information about acoustical, regulatory and related standards, plus a glossary of acoustical terms.

Bruel and Kjaer (B and K) has included new, state-of-the-art measuring microphones and related equipment for the measurement of sound in the latest version of its Microphones and 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 and 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 and Kjaer provides to maintain end-users' equipment and to ensure acoustical measurement integrity through the entire lifetime of the products.

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.

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 0.5in low-noise microphone and pre-amplifier is a 0.5in all titanium TEDS microphone with a guaranteed noise-floor less than 6.5dB(A).

It is optimised for sound power measurements to ISO3745 and for characterising the noise floor of anechoic chambers.

Type 4950 0.5in 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 16kHz, and its dynamic range (with pre-amplifier type 2669) is 14 to 142dB(A).

Types 4954 and 4954A 0.25in prepolarised free-field microphones conform to standards IEC61094-4 WS3F.

Its optimised frequency response (+/-2dB) is 4 to 80kHz, and its dynamic range (with pre-amplifier type 2670) is 40 to 164dB(A).

Type 4954A has an integral Deltatron preamplifier and is identical to type 4954 in all other respects.

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.

Bruel and 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 handheld analyser, fundamentals of measuring sound, and accelerometer mounting techniques.