If you have ever listened to a playlist on your iPhone while wearing headphones, you have likely experienced the jarring shock of a quiet acoustic song finishing, only for a heavy metal track to instantly blast at a significantly louder volume. This happens because individual audio files are mastered at drastically different decibel levels during the recording process.
Instead of frantically adjusting the volume buttons on the side of your phone after every single song, you can enable a hidden audio equalization feature built directly into iOS called “Sound Check.”
How to Enable Sound Check
This setting is specifically designed for the Apple Music app and audio files synced locally to your device via a computer.
- Open the Settings app on your iPhone.
- Scroll down through the list of default Apple applications until you find Music. Tap it.
- Look under the “Audio” section.
- Locate the toggle switch labeled Sound Check.
- Toggle this switch to the On (green) position.
How the Feature Works
When you enable this toggle, your iPhone performs a rapid mathematical analysis of every song in your library. It identifies the peak volume of the loudest song and the baseline volume of the quietest song.
It then actively applies a dynamic software filter in real-time. If a song is mathematically determined to be too loud, iOS will quietly reduce its gain. If a song is too quiet, it will boost it. The end result is that every single song you listen to will play at an identical, normalized volume level, completely eliminating audio whiplash when transitioning between different albums or artists.
Note: If you use third-party applications like Spotify or YouTube Music, this iOS setting will not affect them. You will need to dig into the individual settings menu of those specific apps and look for their proprietary “Audio Normalization” toggles.