scott suggs , 28 , and brandy kangas , 36 , locked three children in room .
room was ` sparsely furnished ' and stained with human urine and feces .
girls , three and four , and 17-month-old boy were fed meals through gate .
couple were arrested after police received anonymous tip about abuse .
both given six-year suspended sentences after admitting child neglect .
victims , who lacked social skills when found by police , are now in care .