If you have access to SSH you can reduce the fan speed but I think for latest innosilicon firmware are all SSH disabled so you can't reduce the fan speed.
I heard that some miners use an adapter called NA-FC1 to reduce the amp flow from the PSU to reduce the speed of the fan but it seems it won't work according to some response from
other thread .
Try to access the SSH with this passwords below
Innosilicon root innot1t2
Innosilicon root t1t2t3a5
Innosilicon root blacksheepwall
Use this command to manually set the fan speed.
"fanspeed":"80"
"automatic":"manual"
The "80" is the percentage of your fan speed. but if the SSH password above doesn't work better to move on because reducing fan speed will increase temp that can damaged chips as philipma1957 said.