This shrill sound captured in the video continues to disrupt people in Writtle overnight.
The piercing alarm-like noise, which is thought to emanate from a nearby farm, has confused and frustrated homeowners in equal measure.
People nearby came forward to the Essex Chronicle Facebook page with their own theories, and reader Andrew Clugston sent in his own evidence.
Do you know what it is or where its from? Email the newsroom on newsdesk@essexchronicle.co.uk
