A free app for Android, by Sonic Innovations Inc..
Sonic SoundLink 2 is a free, versatile hearing aid app for Android.
You can connect your device to your hearing aids using the built-in Bluetooth or Wi-Fi connection.
You can control the hearing aids using the Android device’s built-in microphone or earpiece. You can choose between different sound settings, including normal, quiet, and loud.
The app allows you to mix your voice with the audio coming from the microphone.
The app can also play a selected sound from the device or the app’s memory.
If you are using a smartphone or tablet, you can also use the app to access the Sonic service on IFTTT.