FLC OF A B767 FOUND THAT THEY WERE OFF FREQ FOR 2 MINS DURING THE TIME THEY WOULD RECEIVE DSCNT CLRNC ON START OF STAR ARR. AFTER BEING ALERTED BY COMPANY RADIO; THE CAPT RETUNED THE RADIO TO THE PROPER FREQ AND RECEIVED VECTORS TO CIRCLE IN GETTING DOWN SUFFICIENTLY FOR THE ALT DESIRED AT THE NEXT STAR FIX.

Narrative

ON ARR INTO SLC CLRED BY CTR ALONG SPANE ARR. WE HAD A ZLC CTLR ON FAM RIDE IN COCKPIT JUMP SEAT AND DISCUSSED THE FACT THAT WE WERE GIVEN DSCNT FROM 35000 FT TO 31000 FT LATER THAN USUAL. PRIOR TO ANY DSCNT WE HAD CALLED CABIN TO CHK ON PAX WHEELCHAIR NEEDS IN SLC AND FLT ATTENDANT SAID THEY'D HAVE TO CALL US BACK. AT 31000 FT; HANDED OFF TO SLC APCH. CHKED IN; THEN FLT ATTENDANT CALLED CAPT; TALKED ON INTERPHONE; BRIEFLY. I CONTINUED LISTENING WATCH ON #1 COM WHICH HAD BEEN SLC APCH. CAPT REJOINED ME ON #1 AFTER INTERPHONE. WE TALKED ABOUT NEED TO DSND IF WE WOULD MAKE THE USUAL CLRNC TO CROSS SPANE AT 16000 FT FOR N LNDG. THERE WERE NO XMISSIONS ON #1 RADIO. SELCAL CHIME SOUNDED; CAPT ANSWERED ON #2 RADIO; SAID SOMETHING ABOUT SWITCHING THEN MOVED FREQ SELECTOR ON #1 COM AND CALLED SLC APCH. WE WERE IMMEDIATELY GIVEN TURN; AIRSPD REDUCTION AND DSCNT TO 25000 FT. I ASKED WHAT HAPPENED AND CAPT SAID THAT WHEN GOING TO INTERPHONE HE HAD APPARENTLY MOVED FREQ SELECTOR AND WE HAD BEEN OFF ATC APCH FREQ WHILE THEY TRIED TO REACH US FOR DSCNT. WE WERE GIVEN FURTHER DSCNT VECTORS BY APCH AND AN UNEVENTFUL VISUAL APCH TO RWY 34R WAS MADE. TIMING OF UNNECESSARY COMS SET UP CHAIN OF EVENTS. MUST EXERCISE CARE WHEN MAKING MANY SELECTIONS ON AUDIO PANEL IN SHORT TIME. WE WERE OFF ATC APCH FREQ FOR ABOUT 2 MINS AT A CRUCIAL TIME OF SEQUENCING FOR ATC. QUESTION ATC IMMEDIATELY WHEN 'OUT OF ENVELOPE' SITS BEGIN TO DEVELOP. WATCH FREQ WINDOWS AND SELECT KNOBS VERY CLOSELY DURING PANEL SELECTION TO CATCH INADVERTENT ERRORS. SUPPLEMENTAL INFO FROM ACN 410810: WE WERE NEAR OUR TOP OF DSCNT POINT FOR THE ARR AND WE TRIED TO GET A WORD IN ON THE CTR FREQ; 133.9; BUT HE WAS QUITE BUSY; AND WE THOUGHT HE WOULD GIVE US A LOWER ALT SOON. WE WERE DISTRACTED BY THE FLT ATTENDANT REGARDING IN-RANGE CUSTOMER INFO.