Passive acoustic surveys conducted between 2008 and 2020 in pond, lake, stream, and river habitats in the New England region of the USA found the soundscape of tidal rivers to be dominated by an unidentified fish sound. The sound, designated rumbles, can be grouped into three types: rumble-groans, rumble-rattles, and rattles based on the occurrence of broadband knocks, and are characterized by a peak frequency of 256 Hz, 90% bandwidth of 541 Hz, and 90% duration of 1.6 s. The sounds have been observed from late April through July with chorusing occurring after sunset. The spatial and temporal distribution of the rumbles closely matches that of the white catfish, Ameiurus catus, and the Atlantic and shortnose sturgeons, Acipenser oxyrinchus and A. brevirostrum. Although the white catfish cannot be completely ruled out, all ictalurid catfish are thought to only produce stridulation sounds, leaving sturgeon as the most likely source of the rumbles. If further research confirms rumbles are produced by sturgeon, that would suggest that PAM can be a powerful tool to document the spatial and temporal patterns of sturgeon spawning throughout their range.