January 20, 2016An inexplicable and infamous humming sound that once tormented residents of Bristol, England has seemingly resurfaced in recent weeks.The incessant low-pitched noise was first reported in the 1970's, when denizens of the city began complaining to authorities about the sound that would eventually become known as the 'Bristol hum.'Despite a myriad of theories for the sound's source as well as reports of similar noises in other parts of the UK, the mystery fell by the wayside after the noise apparently ceased for no reason.However, recent reports from Bristol indicated that the city's notorious hum may have returned with a vengeance as numerous people have taken to social media to report hearing it once again.Some experts have suggested that the hum is caused by waves vibrating the ocean floor while other theorize that people hearing the hum are actually afflicted with tinnitus.For those in Bristol suffering through the hum's resurgence, any explanation for its source will likely suffice so long as it stops soon.Source: BBC News