Guides to the diction of foreign languages have been published for singers.
A Handbook of diction for singers: Italian, German, French. (MT 883 .A29 H36 2008)
International Phonetic Alphabet for Singers. (MT 883 .W21 I58 1989)
Search these and other diction guides in the Library's catalog using this subject heading:
You can also find them shelved under the call numbers MT 883 and MT 872.
The International Phonetic Alphabet
Developed by linquists, the IPA has symbols representing all known sounds of spoken language (distinguishing, for example, between long and short "a").
Singers and actors use the IPA as a diction aid.
Some IPA guides:
International Phonetic Alphabet for singers: a manual for English and foreign language diction. (Call number: MT 872 .W187 1989)