Mysterious Bristol 'hum' in the sky returns

Footage has emerged from Bristol, United Kingdom, where a mysterious low-level hum seems to plague the city.

In the video, reportedly filmed last week, the filmer is working in his loft when suddenly a strange noise comes from outside. He opens his window with the camera still running to show the phenomenon that appears to be coming from the sky.

According to local media, these kind of sounds are not just affecting Bristol but other towns across Britain. There are different theories about the hum and its origin but one suggestion from French scientists is that the noises are the effect of continuous waves causing the ocean floor to vibrate.