Air carrier flight crew report communications difficulties with MDT Ground after landing and critical conflict with EMB110 during taxi to gate.

Narrative

We executed a flaps 35 degree landing; and cleared the runway at taxiway E. MDT Tower instructed us to switch to Ground Control. I contacted Ground and stated; 'flight XXX clear of Runway 31 at taxiway E for taxi to the gate.' Reception of Ground Control transmissions was weak at best; but we were instructed to taxi to the gate; and I read back the clearance. I informed Ground that they were 'Weak; and not very clear;' and they responded by stating; 'It's because you're using noise canceling headsets.' All radio transmissions on other frequencies up till this point were loud and clear; and in the 3 previous legs in this aircraft we had noted no problems. As the Captain began to taxi the aircraft; I commenced the after landing flow and then checklist. After several seconds of taxi; with my head down reviewing the checklist; I heard an exclamation from the Captain; and felt our aircraft brake to a stop rapidly. I looked up to see an EMB110 aircraft coming directly at us from our right on taxiway G; oblivious to our presence and closing on us. The EMB110 made a quick turn onto the cargo ramp; missing us by a short distance; possibly 40 FT. I am unsure if the EMB110 crew ever saw us. We waited until the intruding aircraft was out of the way; and taxied to the gate normally. Another aircraft seemed to be disoriented on the airport surface; and ended up in close proximity to us. Communications with Ground Control were hampered by radio problems static -- weak transmissions on the Tower's Ground Control radio. Even if Ground Control had been giving the EMB110 crew more detailed taxi instructions; it seemed doubtful that they would have understood the transmissions due to the quiet; staticy qualities of the Ground frequency that night. Ensure that Ground Control frequency is working properly; and don't allow Controllers to blame communication problems on 'noise canceling headsets;' which are obviously not the problem and have no bearing on the near miss situation. As for the EMB110 crew; I'm not sure what they saw which caused them to approach our aircraft in such a manner. Supplemental information from ACN 821006: I think that the main cause was Ground Control's poor radio quality and the Controller's cavalier attitude; as evidenced by his comment about noise canceling headsets. The First Officer had a noise canceling headset; but that feature was turned off. My headset is not noise canceling and I couldn't hear his transmissions either. If he had switched radios; we probably would not have had the communication problems and would have heard about the other aircraft earlier and been able to avoid such a close encounter. We had no problems hearing the Tower's transmissions.