Brüel & Kjær Launches Type 4988-A 1/4" Pressure-Field Measurement Microphone

November 15 2019, 00:20
Bruel & Kjaer has a new miniature microphone ideal for high-precision acoustic measurements tests within confined spaces – Type 4988-A. A mini, yet mighty microphone, this new 1/4" low noise, prepolarized, all titanium microphone from Brüel & Kjær was designed to help engineers and acousticians achieve accurate measurements in everyday tasks. The new Type 4988-A is flat from 20Hz to 20KHz (±1 dB) and can be used close to hard reflective surfaces, or very close to sound ports of an audio device (near field).

Type 4988-A’s all-titanium design is highly resistant to corrosion and suitable for a range of acoustic tests, even in the presence of magnetic fields. It’s practically immune to temperature and humidity changes; this extreme stability, combined to a minimal spread in frequency response between individuals make it ideal for integration in a production line or for general audio measurements. 

The 1/4" low noise (29 dB A inherent noise) microphone is optimized for use in pressure-field applications such as use with couplers, measuring close to audio device sound ports or flush-mounting. The microphone also works as a general measurement device when the operator makes use of the inclusive electronics corrections; these include response at different angles of incidence in a free field, corrections in a diffuse field or grid influence.

The microphone has a laser welded diaphragm and is paired to a 1/4" Constant Currant Line Drive (CCLD) preamplifier. This connects to CCLD input conditioning, ensuring all measurements meet the industry standard IEEEP1451.4 V1.0. Recommended applications include measurements requiring an EN/IEC 61326 EMC compliant product, measurements in small acoustic chambers and test boxes where reflections occur, measurements in unpredictable sound field conditions, and use as a reference microphone for tuning of microphone arrays and active noise-cancelling systems.

More information about Type 4988-A microphone is available on Brüel & Kjær’s website:

Brüel & Kjær is currently promoting a trade-in campaign for old microphones, regardless of what condition they are in – even for non-functioning microphones. The trade-in offer is not even limited to Brüel & Kjær microphones. Any standard measurement microphone can be traded in.

Since January 1st, 2019, Brüel & Kjær merged with Hottinger and are now HBK (Hottinger, Brüel & Kjær,) a subsidiary of UK-based Spectris plc. Brüel & Kjær focuses on sound and vibration solutions and develops advanced technology for measuring and managing sound and vibration. -
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