A B737-400 LOST CABIN PRESSURIZATION DURING DSCNT. AN EMER WAS DECLARED AS THE CABIN ALT WARNING HORN SOUNDED; BUT THE MASKS DID NOT DEPLOY.

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SHORTLY AFTER WE STARTED OUR DSCNT; IT WAS NOTICED THAT THE CABIN WAS CLBING AT 1000 FT PER MIN. I SET THE CABIN PRESSURIZATION CTL TO STANDBY IN AN ATTEMPT TO REGAIN CTL OF THE CABIN. WE ENSURED THERE WERE TWO PACKS ON; TWO BLEED AIR VALVES OPEN AND THE OUTFLOW VALVE CLOSED; BUT IT KEPT CLBING AT 1000 FT PER MIN. WE THEN WENT TO MANUAL ON THE OUTFLOW VALVE TO ENSURE THAT IT WAS CLOSED. THE ALT WARNING HORN SOUNDED AS I WAS ARRANGING A RAPID/EMER DSCNT WITH ATC. WE THEN STARTED THE EMER CHKLIST WITH 'RAPID DEPRESSURIZATION/CABIN ALT WARNING HORN' FOLLOWED BY THE EMER DSCNT CHKLIST. AN EMER WAS DECLARED WITH ATC AT FIRST CONTACT FOR THE DSCNT AND AGAIN WITH APCH. WE DSNDED TO 10000 FT INITIALLY AND WITHOUT ALLOWING THE CABIN TO CLB ABOVE 10500 TO 11000 FT; I BELIEVE. THE EMER OXYGEN MASKS WERE NOT DEPLOYED IN THE CABIN AS THE CABIN ALT DID NOT REACH 14000 FT. THE ACFT BRIEFLY EXCEEDED V1 IN THE EMER DSCNT. AT 7000 FT; APCH ASKED IF WE WANTED TO TERMINATE THE EMER AND IF WE STILL NEEDED EMER EQUIP. I ELECTED TO TERMINATE THE EMER AFTER CHKING WITH THE FLT ATTENDANTS FOR ANY INJURIES OR PROBS. EVERYTHING IN THE CABIN WAS ALL RIGHT AND THE PAX WERE UNAWARE OF THE PRESSURIZATION PROB. AN UNEVENTFUL LNDG WAS MADE. CLOSE MONITORING OF THE SYSTEM IN QUESTION ALLOWED US TO MITIGATE THE EFFECTS OF THE MALFUNCTION. TRYING TO CONTACT ALL THE NECESSARY PARTIES ADDED TO THE TASK SATURATION PROB.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT ON A FOLLOWUP WITH MAINT; HE LEARNED THE L ENG PRESSURE REGULATOR WAS MALFUNCTIONING AND THE R AIR CYCLE MACHINE WAS MALFUNCTIONING. RPTR ALSO STATED THAT ALTHOUGH HE GUESSED THE CABIN ALT WARNING HORN WOULD SOUND; THE CREW HAD A DIFFICULT TIME LOCATING THE HORN SILENCING BUTTON.