underwater acoustic intensity probes, underwater acoustic impedance probes, and associated calibration systems, namely, p-u acoustic intensity probes, which are underwater acoustic intensity sensors for measuring acoustic pressure and particle velocity; p-a acoustic intensity probes, which are underwater acoustic intensity sensors for measuring acoustic pressure and particle acceleration; p-u acoustic impedance probes, which are underwater acoustic impedance sensors for measuring acoustic pressure and particle velocity; p-a acoustic impedance probes, which are underwater acoustic impedance sensors for measuring acoustic pressure and particle acceleration; suspension springs for suspending acoustic intensity probes and acoustic impedance probes within a positioning tube; preamplifiers for conditioning the output signals of acoustic intensity probes and acoustic impedance probes; flow shields for reducing flow-induced noise on acoustic intensity probes, acoustic impedance probes, and other underwater acoustic sensors, namely, conventional hydrophones; traveling wave calibrators for calibrating underwater acoustic transducers; standing wave calibrators for calibrating underwater acoustic transducers; u-u intensity probes; p-p intensity probes; acoustic tensor sensors; and acoustic vector sensors