Since its establishment in 1994, GRAS has been totally dedicated to the development and manufacture of high-quality measurement microphones and related acoustic equipment.  It was founded by the Danish acoustics pioneer, Gunnar Rasmussen, who has been a major contributor to the world of sound and vibration with his unique ideas and designs.  From the first reproducible 1” condenser measurement microphone that enabled quality measurements and instrumentation for acoustic calibration, Gunnar’s ingenuity and foresight led to the world’s most popular acoustic sensor:  the ½” measurement microphone.  The ¼” and 1/8” microphones followed with outstanding dynamic and high-frequency capability that brought higher definition and transparency into impulse noise diagnostics.  Many variants have been made available for the years; all based on Gunnar’s original 1” pressure microphone design.



GRAS NA, Inc. was established in May 2002. As a subsidiary of GRAS Sound & Vibration A/S in Denmark, our main goal is to provide excellent customer service and support as well as grow the GRAS experiences in the United States.

Ed Okorn

Ed Okorn

General Manager NA



Robert K. O’Neil

Applications Engineer



Bob joined GRAS Sound & Vibration in 2013 as a general Field Applications Engineer.

Bob has many years of experience in Ultrasonics, working with polycrystalline piezo ceramic and single crystal PMN-PT materials. Bob has degrees in both Physics and Electrical Engineering with many graduate classes such as MEM's, Finite Element Analysis, Optics, Acoustics, Continuum Mechanics, and Transducers from several fields of study. His primary interest is in transducers, their performance and how they solve the customers’ challenges/application.

His focus is to support our Industry Managers, Sales Partners and customers in any application. Bob spends a lot of time with telephone support, testing and calibration in our in-house calibration lab and visiting customer with local sales partners.



When our R&D team develops a measurement microphone, it must undergo the most demanding tests to prove that it deserves to bear the GRAS name. Using a series of “Highly Accelerated Life Tests” we ensure that our microphones live up to the high quality and precision that our customers have come to expect and trust. Our HALT tests actively accelerate the lifetime of a microphone by simulating the handling and use it is exposed to in real life situations.

We bake it, we humidify it, we shake it and we even try to break it, just to make sure that you get the very best measurement results every time. Learn more about our microphone HALT testing here.

All our microphones are solely produced in stainless steel and in a quality that allows for a 5 year warranty. Should you by mistake damage the diaphragm on a GRAS microphone, our special technique enables repair at very reasonable price.

GRAS is ISO 9001:2015 and ISO 17025:2015


GRAS is represented worldwide in more than 40 countries by subsidiaries and distributors. Whether you are searching for a multi-channel solution or just a replacement microphone for your sound level meter GRAS will help solve your needs.