A free program for Android, by Kaydev2.

Sound Booster for headphones is an Android audio-boosting app that is designed to increase volume levels of audio output from your device. It offers various presets and audio effects to make your audio output louder. It is also compatible with all Android devices.

The best part is that you don’t need to download any other apps. Simply install this one on your device, and you are good to go!

The sound will be boosted in both volume and bass. You will also get an option to set a higher volume level for all apps, so you can still listen to all of your favorite music, movies, and podcasts.