The first time you use "voice mode" with Ima, you will see this:
To listen to the other options, tap on an arrow to move in that direction as shown below:
To change Ima's voice later, tap on the little circle in the upper right corner as shown below (NOTE: The circle will show your initials.)
In the settings window, tap on "Speech" and then tap on the little arrow to see the voice options, as shown below: