OBSI System Overview AVEC, Inc. offers an On-Board Sound Intensity (OBSI) system to measure tire-pavement noise. The hardware and software specifications are based on the current AASHTO standard (T 360-16: Standard Method of Test for Measurement of Tire/Pavement Noise Using the On-Board Sound Intensity (OBSI) Method). The software and hardware components can be bought separately to upgrade an existing system or as a turn-key system including: AVEC's OBSI Software with USB remote for easy software control. AVEC's OBSI Fixture (see details below). Two (2) GRAS 1/2" Intensity Probes (4 microphones), IEPE or externally polarized. National Instruments DAQ (USB-9234, 4 channels). GRAS 42AB Sound level calibrator. Semi-rugged Laptop (with software pre-installed). Plastic carrying case for OBSI system. Wind screens and cables for intensity probes. DC/AC converter. Required tools. Other optional items include: Laptop car mount. Standard tire and wheel hub.