A B737-300 FLC PERFORMED A RAPID DSCNT FOLLOWING DELAYED RECOGNITION OF A SLOW CABIN PRESSURIZATION LOSS INDICATED BY A DUAL PURPOSE AURAL WARNING HORN.

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THE FIRST INDICATION OF A PROB WAS WHEN THE AUTOTHROTTLE DISENGAGED AND WOULD NOT RE-ENGAGE. WE SENT COMPANY MAINT A MESSAGE AND THEN DIDNT THINK TOO MUCH OF IT. SHORTLY THEREAFTER; ATC RPTED THAT THEY WERE NOT RECEIVING OUR TRANSPONDER. WE SWITCHED TO THE 'R' TRANSPONDER AND ATC RPTED THEY WERE NOW RECEIVING IT OK. THE CAPT BEGAN THINKING THAT THE AUTOTHROTTLE AND TRANSPONDER ISSUES WERE RELATED SOMEHOW AND MIGHT HAVE TO DO WITH AN AIR-GROUND SENSING PROB. BOTH THE CAPT AND FO GOT OUT THEIR FLT MANUALS TO START RESEARCHING THE POWER SOURCES FOR THESE TWO ITEMS. THE NEXT THING THE CREW HEARD WAS AN INTERMITTENT HORN SOUNDING IN THE COCKPIT WHICH WE INTERPRETED TO BE THE TKOF WARNING HORN. IN OUR MINDS WE WERE DEALING WITH AN AIR/GROUND SENSING PROB AND THE TKOF WARNING HORN SOUNDING WOULD NOT HAVE BEEN AN UNUSUAL THING TO HAPPEN IN THAT SIT. AFTER APPROX A FEW MINUTES THE FO REMEMBERED THAT THE TKOF WARNING HORN ALSO DOUBLES AS THE CABIN ALT WARNING HORN. HE CHECKED THE CABIN ALTIMETER AND SAW THAT IT WAS ABOVE 10000 FT. THIS IS WHEN WE REALIZED THE CABIN WAS SLOWLY LOSING PRESSURE. WE DONNED OUR OXYGEN MASKS AND ESTABLISHED CREW COMS AND COMPLETED THE APPROPRIATE QRC. CLRNC WAS RECEIVED FROM ATC TO DSND FROM FL370 TO 10000 FT AND A RAPID DSCNT WAS INITIATED. THE CABIN ALT NEVER REACHED 14000 FT; SO THE PAX OXYGEN MASKS WERE NOT DEPLOYED EITHER MANUALLY OR AUTOMATICALLY. UPON REACHING 10000 FT WE LEVELED AND COMPLETED THE REFERENCE ACTIONS FOR THE CHKLIST. THE CAPT CONTACTED DISPATCH AND MAINT TO RPT THE SIT. CAPT'S EMER AUTHORITY WAS USED TO PULL AND RESET CIRCUIT BREAKERS PER INSTRUCTIONS FROM MAINT. UPON RESETTING THE LANDING GEAR AIR/GROUND RELAY CIRCUIT BREAKER; ALL SYSTEMS RETURNED TO NORMAL. AFTER CONSULTATION WITH DISPATCH; MAINT; THE FLT DUTY OFFICER; AND THE FO; AND CAPT MADE THE DECISION TO DIVERT THE FLT AND LAND IN ZZZ DUE TO A LACK OF FUEL TO SAFELY CONTINUE TO OUR ORIGINAL DEST. THE FLT ATTENDANTS AND PAX WERE BRIEFED ON THE SIT AND A NORMAL; UNEVENTFUL LNDG WAS ACCOMPLISHED IN ZZZ. A SAFETY ISSUE I WOULD LIKE TO RAISE AWARENESS ABOUT BASED ON MY EXPERIENCE; IS THE LACK OF WISDOM IN HAVING THE TKOF WARNING HORN DOUBLE AS THE ALT WARNING HORN. BECAUSE THE CABIN WAS LOSING PRESSURE SLOWLY; WE DID NOT FEEL ANY PRESSURE CHANGES IN OUR EARS THAT WOULD HAVE NORMALLY SERVED TO ALERT US TO A PRESSURIZATION PROB. IF THE FO HAD NOT HAPPENED TO REMEMBER THAT THE HORN ALSO SERVES AS A CABIN ALT WARNING HORN; WE MAY HAVE CONTINUED TRYING TO TROUBLESHOOT THE AIR/GROUND PROB UNTIL PASSING OUT FROM LACK OF OXYGEN. FLT CREWS ARE NOT ACCUSTOMED TO ASSOCIATING AN INTERMITTENT HORN WITH THE CABIN ALT WARNING SYSTEM. DURING THE CAPT'S COCKPIT SETUP THE INTERMITTENT HORN IS TESTED BY ADVANCING A THROTTLE TO CHECK THE TKOF WARNING SYSTEM. LIKE PAVLOV'S DOGS; THIS FORMS THE HABIT PATTERN OF ONLY ASSOCIATING THAT SOUND WITH THAT SYSTEM. THERE IS NO TEST PERFORMED ON THE CABIN ALT WARNING SYSTEM AND AS A RESULT THERE IS NO PARTICULAR SOUND FLT CREWS ARE TRAINED TO ASSOCIATE WITH THAT SYSTEM. HEARING THE INTERMITTENT HORN ONLY SERVED TO REINFORCE IN OUR MINDS THAT WE ARE DEALING WITH AN AIR/GROUND SENSING; TKOF WARNING HORN PROB AND DISTRACTED US FROM THE MORE SERIOUS PROB OF LOSING CABIN PRESSURE. SOMETHING AS IMPORTANT AS THE CABIN ALT SHOULD HAVE A WARNING SYSTEM WITH ITS OWN UNIQUE SOUND THAT CANNOT BE ASSOCIATED WITH ANY OTHER PROB. I WOULD SUGGEST A VOICE THAT SAYS 'CABIN ALT.' PLTS CAN BE TRAINED THAT HEARING THAT SOUND ONLY MEANS ONE THING; 'PUT YOUR MASK ON NOW!' CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CAPT STATED AGAIN THAT THE 'PAVLOV EFFECT' CAUSED BOTH CREW MEMBERS TO FOCUS IN THE WRONG AREA FOR A HORN CAUSE. THE FO HAPPENED TO REMEMBER ABOUT THE CABIN ALT WARNING. THIS CREW MEMBER STATED THAT FROM HIS PERSPECTIVE A VERBAL ALERT SUCH AS 'CABIN ALT' WOULD BE PREFERENTIAL. THERE ARE TOO MANY AURAL SOUNDS NOW AND MANY OF THEM DO HAVE UNIQUE CAUSES.