Ilyas Ashar, 83, and wife Tallat, 66, regularly beat the girl – dragging her by the hair if she was too slow and slapping her if the food was too hot or spicy.
Peter Cadwallader, prosecuting, said the girl had been brought from her home in Pakistan in 2000 after being told her parents had died.
Profoundly deaf and unable to speak, she went to live with the Ashars at their Victorian house in Eccles, near Manchester.
'She was brought to this country and exploited,’ said Mr Cadwallader. ‘She was a victim of threats and violence throughout her life from being a little girl.
'She was the subject of forced labour in that she was made to work for Ilyas and Tallat Ashar as a domestic servant and do other work for them.
illyas (left) and Tallat (right) Ahsar deny charges of false imprisonment, human trafficking,violence
and benefit fraud
'She was made to cook, clean and do the washing and ironing. She was also made to clean houses and business premises for friends and relations of Mr and Mrs Ashar.
'She also washed cars in the drive of the house – in essence she lived in a state of servitude.’
'At night the door at the top of the stairs down to the cellar was locked and bolted so she could not get out during the night.
'During the day, presumably when she displeased Tallat Ashar, she was pushed into the cellar, pushed down the stairs and the door locked. She would sit there for hours crying and locked in.’
Police called at the house in 2009 and found the girl – now aged around 19 – sleeping in the cellar.
It is alleged that the 10-year-old girl was kept in a cellar at the family's home (pictured)
The Ashars, who ran a market stall and sold cars, both deny two counts of human trafficking for exploitation and a single count of false imprisonment.