Plymouth residents have been hearing strange sounds for years. Image Credit: CC BY-SA 2.0 Derek Harper
Plymouth resident Joao Caetano managed to make a recording of the eerie sound on his mobile phone
The city, which is situated on the southern coast of England, is certainly no stranger to unusual noises thanks to what is known as the 'Plymouth Hum' - a mysterious low droning sound that authorities have been struggling to explain for years.
Hundreds of people claim to have heard the hum with some maintaining that it has even prevented them from sleeping at night. One theory suggests that the humming noise may be caused by waves vibrating on the sea floor - something that only a small percentage of people can hear.
This new sound however, which you can listen to below, seems to be something else entirely.