In 2014, Toyota introduced Easy Speak. Easy Speak is a feature in Toyotas like the Sienna and Highlander. The purpose of Easy Speak is to use the audio system's microphone to pick up sound from the front of the car and play it back in the speaker system so that it's easier for the rear passengers to hear. So when it's on, the people in the rear of the car should be able to hear the driver talk through the speakers. The volume is adjustable in Menu > Setup > Audio > Driver Easy Speak. It looks like that's also where you turn it on and off, although the manual says you can add an on/off to the Home Screen as well.
In Toyota's words "Driver Easy Speak utilizes the vehicle's built-in microphone to amplify the driver's voice through the rear speakers. This feature can be controlled via the touch-screen audio system. There are 4 volume settings. This feature automatically turns off when any door (including the liftgate) is opened. It must be turned on every time you enter the vehicle."
This feature can show up on the home screen of the 3.0 Toyota radios we sell. Cx may complain that Easy Speak is on their home screen and can't get rid of it. Unfortunately the only way to get rid of it is to add the navigation module to the radio upgrade. We still haven't figured that part out. Once or if we do figure the navigation module part of this radio upgrade then the Cx could put the GPS maps on the home screen instead of Easy Speak. Easy Speak can't be removed from the radio. Only turned off and on in the settings.