ACR FLT CREW DSNDS WITHOUT ATC CLRNC; SIMILAR CALL SIGNS.

Narrative

OUR CREW WAS FLYING ACR X FLT FROM LGA TO BTV. WE WERE 40 NM SE OF ALB VOR DIRECT TO BTV IN AN AREA WHERE NUMEROUS ACR'S ARE XING. WE THOUGHT WE HEARD THE ZBW ATC CTLR TELL US TO DSND TO 14000 FT MSL FROM 15000 FT MSL. AS WE WERE LEVELING AT 14000 FT MSL THE CTLR CALLED OUT TFC TO US AT OUR 1 AND 2 O'CLOCK POS; AT 14000 FT MSL. WE SAW AND RPTED THE TFC TO HIM. ATC THEN ASKED US WHAT ALT WE WERE AT. WE RESPONDED '14000 FT.' ATC TOLD US WE SHOULDN'T BE AT 14000 FT; THAT WE TOOK ACR Y'S ALT CLRNC INSTEAD. ATC THEN TOLD US TO CLB BACK TO 15000 FT MSL AND REMAIN CLR OF TFC. OUR TCASII SOUNDED AND WE CLBED IMMEDIATELY. NO CONFLICT OF A SERIOUS NATURE OCCURRED AND TFC WAS AVOIDED. WE DID NOT LISTEN CLRLY TO THE ALT CLRNC TO A SIMILAR SOUNDING CALL SIGN. ATC WAS BUSY WITH NUMEROUS CALLS AND DIDN'T REALIZE WE TOOK SOME OTHER ACFT'S CLRNC UNTIL A POTENTIAL CONFLICT OCCURRED. I APOLOGIZED TO THE CTLR WHEN WE LEVELED OFF AT 15000 FT MSL. NO FEELINGS WERE HURT; NO METAL WAS BENT; AND I LEARNED A VALUABLE LESSON: 'LISTEN UP!'