"coreaudio" eating up CPU power

Recently observed a new behavior of some program/routine consuming lots of CPU power. In the cpu monitor app it is identified simply as "coreaudio" or "coreaudiod". It uses 70-95% of CPU power, and this happens when no programs, audio or otherwise, are running. I know the cpu monitor ap is correct because after a short while the fan starts up pretty fast because of the power consumption. Typically the only way to stop this behavior is a restart. Any clue as to what might be causing this?