Audio Problems on Certain Channels

Quincy, MA - Audio on Channels 2 (WGBH) and 16 (WGBX) intermittently lose audio two or three times a minute, and sometimes lose audio entirely.  You have to change the channel and change it back to restore audio, or rewind if you're watching these channels from the DVR.  And now Channel 942 (METV) is garbled with static.  It's not equipment related, it's only on these channels.