Hart was blamed for Birmingham's first equaliser in their 2-2 draw with City on Wednesday night which many feel effectively signalled the end of their Premier League title bid. But, while the England number one acknowledges the right of the doubters to have their say, he does not believe they are accurate.
"People are entitled to their opinions and can say what they want," he said. "But when it comes to football, I focus. I don't know what else there is to think about when you are in goal. What else I could be considered to be concentrating on?"
He added: "It is not as if there is a movie going on in the background or you are doing your homework and a fly comes into the room and you go after it. There is a ball. That is it."
City's encounter with West Brom at Eastlands on Saturday will be a sobering occasion following the death of legendary Blue Neil Young.
The 66-year-old had been ill for some time and fans had already paid tribute to the Fallowfield-born forward by wearing the distinctive black and red colours for the recent FA Cup ties with Leicester that Young was wearing when he scored the winner against the same opposition in the Final at Wembley in 1969.
City are still to emulate that success. Indeed, they have not won a trophy of any description since the 1976 League Cup.
But Hart realises immortality awaits for those who can break the depressing drought.
"It is a sad day for the club," said the England goalkeeper. "Neil was part of the history of this club and was held in high regard by everyone.
"He did so many great things, achieving what the club is striving for now. It shows that doing something like that at a great club like Manchester City can put you down as a legend."