Don't forget to check the Oxford Dictionaries Online database for full-text online dictionaries of several different languages. These dictionaries include audio pronunciation of many words!
Also, remember to consult the online database IPA Source for IPA transcriptions and literal translations of opera arias and art song texts, plus other cool diction (and voice-related0 aids!
Browse these LC class numbers in the Music Reference Section to find opera libretti wtih IPA transcriptions:
(N.B., many of these volumes are in MUSIC REFERENCE; these are noted below.)