Hi @EllenA,
Welcome to your first post in the Roku Community!
Thanks for letting us know about this concern of yours. The Roku Smart Home app requires permission to send and receive audio to use the two-way audio feature. You can check the settings of the Roku Smart Home App on your Android mobile phone to enable the microphone.
For more information about the two-way audio microphone feature, kindly refer to this support article.: How to use two-way audio to speak to visitors with your Roku Smart Home camera or video doorbell
Let us know what you find out.
All the best,
Kash
Takashi O.
Roku Community Moderator