EMB ERJ 145 ER/LR
Troubleshooting; Situational Awareness; Distraction; Confusion; Communication Breakdown
Aircraft Equipment Problem Less Severe
Flight Crew Took Evasive Action; Flight Crew Overcame Equipment Problem; General Maintenance Action; General Flight Cancelled / Delayed
Aircraft
Just after takeoff we experienced intense static over the interphone.  We didn't isolate the problem to the interphone right away though.  We couldn't speak to each other; hear ATC; or speak with our Flight Attendant.  We tried COM 2; one at a time unplugging our headsets; etc and nothing reduced or eliminated the noise. This was far more than rain static noise.  We briefly entered 7600 in our transponder and then found that our speaker worked with using the hand mic.  We ditched using our headsets and continued to our filed destination because weather was better there and would be less busy than our departure airport.  We returned our transponder code back to our issued code when we used the speaker and hand mic.  ATC could hear us the whole time; we couldn't hear them.    We landed and Contract Maintenance operations checked it [as] good. We didn't feel comfortable with that because nothing was re-racked or fixed.  Hours later we were approval for a test flight and briefly flew it to make sure it was OK.  We later flew back empty with no issues.  There clearly was a mechanical issue with this plane that wasn't solved or addressed.  Intense radio static made headset use impossible; O2 mask use impossible (the static noise was present with the boom mask position out but not with the speaker position out).  Had there been a fire communication would have been impossible or if a cabin emergency arose there would have been no way to speak with our Flight Attendant.
Severe internal static developed in an EMB-145 communications system overwhelming all communications so the crew squawked 7600 and ultimately were able to communicate on speaker only while continuing to the filed destination.