Update: this problem was resolved late on the evening of Sat 2/23/13.
We are aware of the technical problems currently affecting KQED World and KQED Life both Over the Air (DT9.3 & DT54.3) and via Comcast Cable (channels 189 & 190). Engineers are working on the problem, but unfortunately we do not expect to be able to resolve it quickly. We apologize for any inconvenience.
We are aware of the lack of sound on current transmission of “Nature: Cold Warriors”. Engineers are working to solve the problem.