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Ultrasound IEC Definition, acoustic oscillation whose frequency is above the high-frequency limit of audible sound (about 16 kHz)
Uncoupled Mode IEC Definition, normal mode oscillating independently of other modes
Undamped Natural Frequency IEC Definition, frequency of free oscillation resulting from only elastic and inertial forces of the system
Undamped Natural Frequency the natural frequency of a structure.
Under-range the input to the Sound Level Meter is too low for the current measurement range. Change the range.
Under-range % percentage of time an under range occurred
Units : SI Units