The configurable items related to Text-to-Speech (TTS) are the rate of speech and the volume. Both items have a default value of 5 on a scale of 1 to 9. (1 being low volume and very slow speech, and 9 being high volume and very fast rate of speech).
The User Dictionary is configurable only through the Web Console. There is one dictionary file per TTS language, and changes made to a single dictionary file will only be applicable for that language. The user can enter a source word and the replacement word (alternate pronunciation) to be used. There is no limit to the number of entries in the file.
Word replacement is case sensitive. If the source string contains upper case letters then the source string must exactly match a word in the email to be replaced. If the source string has all lower case letters, then the replacement will be case insensitive.
Web Console:
Text Console:
Configure Text-to-Speech