NEWLY INST RATED PVT PLT OF A C172 TURNED INBOUND ON THE LOC BEFORE BEING CLRED BY APCH CTL DUE TO TEMPORARY LOSS OF COM WITH THE TWR CAUSED BY THE PLT ACCIDENTALLY TURNING OFF THE MASTER AUDIO SWITCH.

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I WAS THE PF ON MY FIRST IFR XCOUNTRY (IFR FLT PLAN) SINCE RECEIVING MY INST RATING 2 WKS PREVIOUS. I WAS BEING VECTORED TO INTERCEPT THE ILS RWY 33 AT BDL. IN THE C172 AUDIO PANEL IS A SERIES OF SWITCHES. DURING BEING VECTORED I WAS TOLD TO EXPECT ILS RWY 33 AT BDL. AT SOME POINT DURING CHKING ALL THE NAVAID IDENTS ON THE AUDIO PANEL; I ACCIDENTALLY TURNED OFF THE MASTER AUDIO FOR OUR HEADSETS; AND WAS NOT AWARE OF THIS. AT THIS POINT I WAS ON A RADAR VECTOR FOR THE LOC; ABOUT 300 DEG HDG. IT WAS UNUSUAL THAT I WASN'T HEARING ANYTHING ON THE RADIOS; BUT THAT'S HAPPENED BEFORE WHILE OUT FLYING. THE NEEDLE FOR THE LOC BEGAN TO COME ALIVE AND SWING IN. MY PAX HAD ASKED IF I WAS CLRED FOR THE APCH. I THOUGHT THAT I WAS AND INSTINCTIVELY TURNED TO INTERCEPT ILS RWY 33. NOT HEARING ANY ATC CALLS; MY PAX SUGGESTED TO CALL ATC. I DID -- NO ANSWER. THE PROB WITH THE RADIO SWITCHES WAS FOUND; AND I CALLED ATC. (THERE WAS ONLY 1 PUSH-TO-TALK XMIT BUTTON IN THE AIRPLANE.) ATC QUERIED ME WHY I TURNED FOR THE APCH. BEING VERY EMBARRASSED; I TOLD ATC I HAD A RADIO PROB; BUT WAS NOW RECTIFIED. I APOLOGIZED FOR THE MISUNDERSTANDING; AND I WAS CLRED FOR THE APCH ILS RWY 33 BDL. THE REST OF THE FLT WENT UNEVENTFULLY. SUPPLEMENTAL INFO FROM ACN 420070: THIS AUDIO PANEL CONFIGN IS CONDUCIVE TO THESE TYPES OF ERRORS IN THAT THE PLT TENDS TO RELY ON THE MASTER IN AUTO AS OPPOSED TO EACH SWITCH (RECEIVER) BEING SELECTED ON. WITH THE MASTER OFF; ALL INCOMING COM IS SHUT OFF.