Although it had been heard multiple times throughout the summer, there has been a spate of music during the past couple of weeks, NJ.com reported at the end of last month.
"It was like a sickening, pulsing heartbeat. We turned up our television but could not overpower the throb," Monica Morris Lind, who lives off the Delaware River, told the media outlet.
"It's just a severe bass thumping," Bruce Hampton, a resident of Pennsville, told CBS Philly earlier this month.
"Anytime between 3 a.m. and 5 a.m., it could be any kind of music, usually it's like a loud beat," he added.
Pennsville Police Chief Allen Cummings, as well as police in nearby towns, have not not been able to locate the source of the music, even though they have received at least 60 complaints since the summer.
"I think it's a group of individuals that have custom speaker systems in their cars, and they're meeting at certain places and times, and they could be competing to see who has the best speaker system," Cummings told NJ.com.
The Pennsville Police Department did not immediately respond to Sputnik's request for comment.
Master Corporal Michael Austin of the Delaware State Police also told NJ.com that the music could be coming from a barge in the river connected to dredging operations carried out by the Delaware Department of Natural Resources. However, this has not yet been confirmed.
This past summer, loud booming music pulsating across the Delaware River from South Philadelphia turned out to be a showcasing of trucks, cars and SUVs with custom sound systems, ABC News reported in July.