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Cumulative acoustically-induced phase modulation along the sensing fiber significantly degrades the performance of Optical Frequency Domain Reflectometry (OFDR) systems. Here we present a new method to mitigate this phenomenon using hybrid time-frequency interrogation and analysis. The method, which we term Gated-OFDR (G-OFDR), achieves remarkable results: ultra-sensitive dynamic sensing at z≈101km with 1.4m spatial resolution and acoustical sampling rate of 600Hz. As an example, the system detected and recorded, with high SNR, falls of two ~1g paperclips from height of ~20cm, on two fiber sections, 10m apart, at the end of the 101km fiber, without any crosstalk artifacts.