Earpiece Speaker Volume booster is a simple, light-weight audio-control app.
In the options, you can enable an experimental feature which switches the phone to
earpiece speaker phone when it's away from the face and then back to speaker phone close up. This only works on devices with a proximity sensor, of course.
Another experimental feature is that you can significantly reduce the volume of the camera sounds on some devices. Ensure your local laws allow you to do this.
Earpiece Speaker Volume booster is free earpiece speaker app
USE Earpiece Speaker Volume booster AT YOUR OWN RISK. Playing audio at high volumes, especially for a prolonged amount of time, can damage earpiece speakers and/or hearing.
Earpiece Speaker test can also be done by this Earpiece Speaker Volume booster app.
Earpiece's audio boost option instead.