As an AV installer (not Comcast), I can tell you that the first place to try any "strange" or unusual issues is to reboot the cable box. When in doubt, reboot! With that said, this is not a box issue - it's a Comcast-NESN issue. If need be, for now, you can turn up the sound on the TV itself as that stereo signal seems to get through (that's what you hear coming very quietly through the main speakers).
I'm guessing that letters to NECN would be the most effective strategy. I couldn't watch a replay of the Rolling Rally because of it, so they lost a viewer....
Don't hold your breath for an answer from Comcast. I posted the original problem over a year ago. I never recieved an answer from them. I eventually replaced my reciever with one that decodes the audio via the HDMI port. I haven't had a problem since then. I'm guessing it is a decoding problem between your reciever and the cable box.
I have a similiar problem as everyone else. In-game sound is fine (Dolby Digital 5.1 I presume) but commercals and pre- and post-game shows are all greatly attenuated. I have an Onkyo receiver so problem is not limited to Sony. It's unfortunate that Comcast never provided an update on this issue.
I finally called Comcast. They had me unplug the cable box and then replug/reboot. That restored the sound for about 30min, then it went back to the same old problem. A couple of days ago I tried the same thing again, and it restored the sound during the normal broadcast, but now the sound cuts out during commercials. It must be some problem between the cable box and NESN. I can live without the sound during commercials, so I guess I will leave it alone for now. Again, all other stations are fine.
The sound on NESN HD is very low (only a rumble from the woofer speaker). It is fine on SD. The sound on all other HD channels is fine. I use an HDMI cable to my Sony Home Theatre video, and an optical cable for audio, since my Sony doesn't decode sound from the HDMI input. I am pretty sure it is some kind of a decoding problem, but why would it only happen on NESN HD? I have talked to several people who have the same issue. Any ideas? I haven't called Comcast because they will just say it is my Sony, or that they will "look into it".