What was found
CABIN ALT HIGH WARNING ON EICAS WHILE DESCENDING. CABIN ALT REACHED 11,500 RAN THE ASSOCIATED CHECKLIST, CONTINUED DESCENT NO OTHER EICAS PRESSURE MESSAGE APPEARED. FA 1 REPORTED HISSING SOUND FROM L1 DOOR BEFORE WE ADVISED THE FAS OF THE CABIN HI ALT. EMERGENCY DECLARED PERFORMED CABIN DEPRESSURIZATION PER FIM TASK 21-31-00-810-818-A. DID THE PRESSURIZATION PER THE AMM TASK 21-31-00-720-802-A. FCV FOR PACK 1 AND PACK 2 WAS NOT OPENING. PERFORMED VISUAL INSPECTION OF THE LH AND RH PACK PER AMM 21-51-21. FOUND RH PACK DUCT TEAR. REMOVED AND REPLACED PACK 2 OUTLET DUCT IAW AMM 21-51-21AND PACKS OPERATIONAL CHECK GOOD IAW AMM 27-51-00-710-801.