Using your built-in Android eQualizer, Volume Booster Pro adjusts the frequencies of your device and simply makes it louder.
Devices with Android 4.4 Kit-Kat and above can take advantage from the new loudness module running behind the Boost button.
Simply play the demo song and tap on the boost button if available.
Older version should use the slider only.
For maximum results use external speakers or headsets.