Winnie Madikizela-Mandela said that ailing Mandela was unable to talk because of the tubes that have been put in his mouth to clear fluid from the lungs, but he uses facial expressions to communicate, the BBC reports.
However, the doctors have said that they hope to recover his voice, Madikizela-Mandela said.
His condition is such that he has become very sensitive to any germs, so he has to be kept sterile, and therefore the bedroom has been literally converted into an ICU ward, she added.
The 95-year-old returned home in September after spending nearly three months in a Pretoria hospital with a recurring lung infection.
The government has repeatedly said that his condition is critical, and sometimes unstable.