A free program for Android, by FeniKsenia.
The Speaker Booster app lets you increase the volume of audio that comes out of your device’s speakers. It can be used with all kinds of devices and can boost the sound of audio files, video clips, movies, music, and more.
If you have a smartphone or a tablet, you can download this app for free. It works on Android 5.0 and above.
The app is very easy to use and works as easy as a volume button. Just select the audio file or the video clip that you want to boost, adjust the volume and boost, and it’s done.