The usage of external lapel microphones could improve accuracy and ease-of-use, since it's no longer necessary to hold the smartphone in the hand while speaking.
If you are interested in a recommendation from our side, we have successfully tested the Movo PM10 Deluxe Lavalier microphone, which costs approximately $15,-. We have tested it with iOS and Android.
It's also possible to use Bluetooth microphones with Ava. You can find instructions on how to connect a Bluetooth microphone with Ava, here.