The GRAS 40PO series consists of 1/2-inch pre-polarized standard acoustic measurement microphones, offered in two variants: low-sensitivity 40PO-L and high-sensitivity 40PO-H. It is widely applied in high-precision noise & vibration testing including industrial NVH, automotive noise, home appliance acoustics, environmental noise monitoring and acoustic laboratory research.

Following the universal 1/2-inch form factor defined by IEC 61094, it is compatible with most multi-channel noise data acquisition systems. The pre-polarized design eliminates external polarization power supply, and works directly with 24V constant-current signal conditioners. When matched with dedicated preamplifiers, it forms a complete acoustic front-end, accurately capturing full-range sound pressure signals from faint background noise to loud abnormal equipment noise. It is extensively used for sound power testing, order tracking noise analysis, transient impact sound capture and quantitative sound quality evaluation.