LGT FLC FORGETS TO RESET ALTIMETER DSNDING BELOW FL180.

Narrative

I WAS OFF THE ATC RADIO PICKING UP THE ATIS INFO WHEN THE CAPT BEGAN DSCNT. WHEN I RETURNED; THE CAPT BRIEFED ME ON THE CURRENT DIRECTIONS OF HDG; ALT AND AIRSPD. THE CTLR WAS VERY BUSY AND IT SEEMED THAT NEARLY EVERY OTHER INSTRUCTION WAS FOR US -- ALMOST CONSTANT CHANGES IN ALT; AIRSPD AND/OR HDG WITH A FINAL REQUEST TO 'EXPEDITE DSCNT TO 11000 FT.' AS WE LEVELED FROM A RAPID DSCNT THE CTLR QUESTIONED OUR ALT AND ALTIMETER SETTING. WE THEN NOTICED THAT WE HAD NEGLECTED TO RESET THE ALTIMETERS AND HAD LEVELED APPROX 400 FT LOW. IT TOOK LONGER THAN NORMAL TO COPY THE ATIS BECAUSE IT CHANGED WHILE I WAS COPYING IT AND IT TOOK SOME TIME FOR THE NEW ONE TO COME UP. ATC RADIO WAS TALKING CONSTANTLY WITH AN EXCEPTIONAL NUMBER OF CHANGES FOR US SPECIFICALLY. 2-MAN COCKPITS ARE BUSY EVEN DURING A NORMAL DSCNT AND APCH. I'M NOT SURPRISED WE FORGOT SOMETHING; BUT WILL TRY TO DO BETTER IN THE FUTURE. MEANWHILE; ANYTHING THAT CAN BE DONE TO REDUCE RADIO CHATTER; REDUCE VECTORING; AND GIVE PLTS MORE ADVANCE NOTICE ABOUT WHERE THEY ARE GOING IN HIGH DENSITY TFC AREAS WILL BE HELPFUL.