There is no sound in the video of copying Xiaomi camera.

Check whether the sound on the phone is low enough to mute.

Check whether Mijia APP has the right to use the microphone (recording) of the mobile phone. If not, please open the relevant permissions in the phone settings.

There is no sound in the Yuntai version of Xiaomi camera, which may be because the horn button on the right side of Mijia camera interface is turned off. If not, it is recommended to try downloading the APP again.

This should be because your application settings are incorrect. Find the settings again and set them as message reminders.