You must use the text-to-speech (TTS) engine setting tool to make playback adjustments to each of the languages that the Email-by-Phone feature supports.
System Utilities › TTS Engine Settings
In the Voice settings Text-To-Speech window select from the Language Engine drop-down list, the language for which you want to adjust the playback settings.
Select a convenient duration for the silence periods between sentences from the Silence between sentences drop-down list. The available silence duration options range from 0 msec through 1800 msec.
Adjust the pitch of the sound of the user-defined speaker using the Pitch slider.
Adjust the speed at which the message is read using the Rate slider.
Adjust the volume of the user-defined speaker
as desired using the Volume slider.
Note: The Minimum confidence for language detection setting is not
used at this time. Nortel Networks software performs the language detection.