How Sound Check Works in iTunes
Every digital music file includes ID3 tags that contain metadata attached to each song and provide additional information about it. These tags contain things such as the name of the song and artist, album art, star ratings, and certain audio data. The most important ID3 tag for the Sound Check feature is called normalization information. It controls the volume at which the song plays. This is a variable setting that allows the song to play quieter or louder than its default volume. Sound Check works by scanning the playback volume of all the songs in your iTunes library and determining the average playback volume of the songs. iTunes then automatically adjusts the normalization information ID3 tag for each song to adjust the volume to closely match the average of all the songs. Then, all songs play at close to the same volume.
How to Enable Sound Check in iTunes
Here’s how to turn on Sound Check in iTunes on a computer:
How to Use Sound Check With iPhone and iPod touch
If you use a mobile device like the iPhone or iPod touch to listen to music, Sound Check works on iPhone, iPod touch, and iPad, although you don’t set it up through iTunes.
Sound Check-Compatible File Types
Not every digital music file is compatible with Sound Check. iTunes can play some file types that can’t be controlled by Sound Check, which could lead to confusion. However, the most common music file types are compatible, so you can use the feature with your music. Sound Check works with the following digital music file types:
AAC (the default format for the iTunes Store and Apple Music) AIFF MP3 WAV
As long as your songs are in these file types, Sound Check works with songs ripped from a CD, bought from online music stores, or streamed via Apple Music.
Does Sound Check Change My Music Files?
Sound Check doesn’t change the volume of your audio files. Every song has a default volume—the volume at which the song was recorded and released. iTunes doesn’t change that. Instead, the normalization information ID3 tag acts like a filter applied to the volume. The filter controls the volume temporarily during playback, but it doesn’t change the underlying file. When you turn off Sound Check, your music returns to its original volume, with no permanent changes.
Other Ways to Adjust Music Playback in iTunes
Sound Check isn’t the only way to adjust the playback of music in iTunes. You can adjust how all songs sound with the iTunes Equalizer or adjust individual songs by editing the ID3 tags. The Equalizer adjusts how songs sound when played by boosting the bass or changing the treble. This feature is best used by people who understand audio, but the tool offers some presets. These are designed to make specific genres of music—Hip Hop, Classical, and so on—sound better. To access the Equalizer, click the Window menu in the iTunes menu bar on a computer and then select Equalizer. You can also adjust the volume levels of individual songs. Just as with Sound Check, this changes the ID3 tag for the song’s volume, not the file. If you prefer only a few changes, rather than changing your entire library, try this:
