Design and performance of a micro-probe microphone

• Published in: The Journal of the Acoustical Society of America 2004-10, Vol.116 (4_Supplement), p.2618-2618
• Main Authors: Daigle, Gilles A., Stinson, Michael R.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4785440

It is often necessary to measure sound fields in confined spaces where minimum disturbance of the sound field is important. The B&K 4170 is a horn-coupled probe microphone for which a 1.25-mm-i.d. probe is attached to the narrow end of the horn and a 1/2-inch microphone is connected to the wide end. In applications where the confinement of the space is extreme, this probe is too large. The probe section of the B&K 4170 has been redesigned using smaller diameter probes. Simulations were made for probes having outside diameters ranging from 1.25 mm down to 0.2 mm. It was found that acceptable sensitivities could be expected from a probe with 0.2 mm o.d. (0.1 mm i.d.) if the length is less than 1 cm. The micro-probe is connected to a larger cylindrical tube with the correct o.d. for mounting on the B&K 4170 casing. Viscous resistance due to the small diameter provides an almost flat response. Several micro-probes were constructed and their performance measured and compared to the simulated results.