An A321 flight crew declared an emergency and diverted to an enroute airport upon the failure of the right engine.

Narrative

After about an hour into the flight we got a vibration indication on the RIGHT engine in the N2 section. We started to look it up in the QRH and it went away; there were NO indications of vibration; smell; or smoke. We finished up with the QRH and monitored engine closely. Approximately an hour later the RIGHT engine started a muffled popping noise and vibration on N1 was 9.2 and N2 was 5.4; still there was no noticeable vibration but the Flight Attendant's and some passengers could here the noise. We returned to the QRH for vibration guidance; the engine started to spool down so we declared an emergency reporting we were unable to continue to maintain FL330 and requested lower but before we could get the book open we got the ENG 2 FAIL ECAM.I assigned the First Officer to fly the Aircraft; and I ran the ECAM securing the Right engine. We chose a diversion airport factoring weather; runway length and information in the data base. [We] completed supplementary follow up checklist items and check landing data for landing distance and over weight landing. Sent an ACARS message to Dispatch of the diversion; told the flight attendants and explained briefly what was going on to the passengers.The First Officer continued to fly the aircraft to ILS 14R into our diversion airport. The landing was smooth with a vertical speed descent less than 150 FPM. Ground emergency crews followed the aircraft to remote parking. Dispatch was able to arrange portable stairs; so when we arrived the passengers did not have to wait too long before they were in the terminal.