Custom pronunciation in MS Office text-to-speech (TTS)

Hello,

Is there a way to define custom pronunciation or change existing pronunciation for specific words in MS Office (2010 & 2013) text-to-speech (TTS)?

With the exception of Excel, MS Office (2010 & 2013) apps come with a built-in TTS function. It can be activated by first adding the "Speak selected text" shortcut icon to the Quick Access Toolbar (QAT) and then, after selecting the text to be spoken, clicking that icon.

I have found that it works pretty well — certainly well enough for a listener to understand the basic gist or content contained in whatever selected text is being read. However, when confronted with certain specific words or phrases  — particularly those which are probably not in its original vocabulary — TTS offers its best guess at the correct pronunciation but, not infrequently, gets it wrong.

Is there any way to access the MS Office TTS vocabulary (either through a user-interface settings box somewhere or by the use of VBA) in order to define correct pronunciation for words which it currently mispronounces?

Thanks