If you've been to Seattle recently and wondered what that odd "humming" sound was, and why you could hear it all over the western part of town, researchers believe they've found an answer: It's the fish.

West Seattle's bizarre buzzing sound has been so loud as to wake residents up in the middle of the night, reports KING5. "It gets high and lower, and goes away, then comes back," said Julie Schickling, one West Seattle resident, describing the noise to the station. (listen to an audio clip of the phenomenon on YouTube -- humming starts 30 seconds in).

And this isn't the first time the noise has appeared, either. "After a few years of it only coming up once in a while, a few days ago, over the Labor Day weekend, it came up with a vengeance,” said Tracy Record, the editor of the West Seattle Blog, to KPLU.

Now, researchers at the University of Washington's Marine Biology program have developed their own theory. They believe the Midshipman fish, a species found in the Pacific Northwest, could be the cause. Part of the fish's mating call (listen to a version here) involves an extended hum. That hum, produced by male Midshipman fish attempting to lure a mate, can last for hours, as males attempt to out-hum potential rivals.

Scientists told KING5 that the hum from the fish may be reverberating off the hulls of boats and buildings, which then amplify it for miles around.

West Seattle Blog notes that, when a similar situation occurred in 2009, the city tried in vain to pinpoint the source of the hum.