Ultra-small microphone scales new heights

A new, 2.5mm low profile, aerodynamically shaped microphone has been introduced by Bruel & Kjaer to simplify the measurement of true surface dynamic pressure in a number of engineering applications.

A new, 2.5mm low profile, aerodynamically shaped microphone has been introduced by Bruel & Kjaer to simplify the measurement of true surface dynamic pressure (sound pressure) in a number of engineering applications.

The Surface Microphone Type 4949 is 20mm in diameter and 2.5mm in height, including its integrated preamplifier. The acoustic performance (5Hz to 20kHz) and dynamic range (30 to 140dB) of the new pre-polarised device is equivalent to that of traditional, much bulkier flush-mounted microphones.

According to Bruel & Kjaer, the all-titanium microphone can be easily integrated into a flexible mounting pad that eliminates the need to drill holes in the test object and minimises the costs of mounting the microphone. Robust and corrosion-resistant, the surface microphone can withstand harsh environments including wet and oily conditions.

The Type 4949’s profile and flexible, disc-formed mounting pad make it ideal for measurement of dynamic pressure directly on the surface of a aircraft, vehicle or wind power blade or for sound pressure measurements in limited spaces and where flush mounting of conventional microphone/preamplifier combinations would be impossible or may cause undesired side effects.

The microphone is also said to be suitable for a wide range of test and measurement applications including acoustical fatigue testing; aerodynamic noise measurements; noise reduction measurements; transfer path analysis as well as lift and down-force analysis.

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