Sound fields have historically been defined in microphone standards as pressure, free field, or random incidence. Multifield microphones can accurately measure in any field or in any combination of the defined fields. According to GRAS, in all situations, sound fields, and angles of incidence, the new 46BC is compliant with IEC 61672 Limits. The design of this microphone takes advantage of the microphone's small dimensions and slightly enhances the high-frequency content, which results in a perfect microphone for in-cabin measurements or any scenarios where measuring in a random incidence environment is needed.
The new GRAS 46BC CCP 1/4" Multifield Microphone Set, High Sensitivity is a microphone with a specific set of skills, ideal for automotive acoustic assessments, from in-cabin speech transmission index to electric vehicle (EV) inverter switching frequency noise. The microphone is designed with all the benefits of small microphones, but also benefits from the low-noise capabilities of its much larger 1/2" models.
The primary reason that 1/4" microphones had not been used for in-cabin measurements in the past was their noise floor. It was much higher and would miss noise contributors such as road and brake noise, or even the higher frequency contributions that could not be measured by a microphone with a 40 dB(A) noise floor. The high-sensitivity 46BC eliminates this issue. With a noise floor of 24 dB(A), it outperforms all other 1/4" microphones and removes the need for using a variety of 1/2" microphones to only come close to the same data quality.
As a 1/4" microphone, its effect on the environment is reduced, and the effect of the angle of incidence from the sound source is minimal. These are challenges for 1/2" microphones. They have substantial pressure build-ups in front of the diaphragm, which causes additional challenges in a mix of pressure- and free-field environments and can give under-represented data as the angle of incidence increases. In particular, the 46BC benefits from unique tuning of its response curve to be a truly multifield microphone.
Unlike other 1/4" microphones, the 46BC is optimized for use with the protection grid. This feature ensures protection during in-cabin measurements. The microphone requires a constant current input module that can deliver 3.5mA and 24V unloaded CCP voltage supply. The microphone set is terminated with a 10/32 Microdot female connector. Ready-to-use coax cable assemblies of various types and lengths are available in standard as well as customized lengths. The 46BC is IEEE 1451.4 TEDS v. 1.0 compliant.
The combination of small-size benefits, multifield tuning, and the lower noise floor of the new GRAS 46BC essentially provide a microphone that is the best of two worlds for automotive acoustic testing.
GRAS Sound & Vibration is represented through subsidiaries and distributors in more than 40 countries and is part of Axiometrix Solutions, including Audio Precision, and imc test and measurement.
www.GRASacoustics.com
