When Interspect Voice is first loaded, it uses your previous settings to select the headset.  If this hardware is not present when you start Interspect Voice, it uses the default devices set on the Audio tab of the Sounds and Audio Devices Properties dialog of the Control Panel.  To fix this problem, perform the following steps:

1. Click on Settings on the main navigation bar.
2. Click on Voice on the left navigation panel.
3. Uncheck the Enable Voice setting at the top of the page.
4. Check the Enable Voice setting at the top of the page.

After performing these steps, you will hear Interspect Voice announce the welcome message using the selected audio playback device set on this page.  Test to ensure the headset is working by clicking on the Mic Training button on this page.