Prentke Romich Company
http://www.prentrom.com/support/article/1795

Adding a Pause to a Message when Using Acapela Voices

To create a pause in a message you can insert the following macro: \Pau=number\

This inserts, in the speech, a pause of the specified number of milliseconds.

Example: "I am \Pau=2000\ ready." A pause of 2 seconds is introduced after the word "am".

NOTE:  The maximum pause time is limited to 10 seconds