Every phone has an EQ (equalizer) setting which allows you to adjust the sound quality of the music.
If you are using the iPhone music app:
- From the iPhone’s home screen, tap Settings.
- From the sidebar, tap Music. The screen shown below appears.
- Tap EQ. The screen shown below appears.
- Tap a preset, such as Rock. The key is to select a preset that matches the type of music you normally listen to. Keep tapping presets until you find one that gives you the best audio.
If you are using an app such as Spotify or Pandora you will have to go to the settings of that app and adjust them until you find a preset that gives you the best audio.