Does sound check on the iPhone have album mode
Answer

Yes, I am pleased to tell you that Sound Check respects both the track gain as well as the album gain (album mode).



How to use it

Go to Settings &gt; Music &gt; Playback and enable Sound Check.



Please be aware that Sound Check's Album Gain it only works if you


play an album directly


(Library &gt; Artist &gt; 'Album Title' &gt; Play)

play an album directly


(Library &gt; Artist &gt; 'Album Title')

play all albums by an artist


(Library &gt; Artist &gt; Play)

play all albums by an artist shuffled


(Library &gt; Artist &gt; Shuffle)





This enables Sound Check's Track Gain:


the song appears in a playlist


even if you exclusively add all tracks of an album a play it in the correct order

you play a single song using (Spotlight) Search




Validation

To understand the algorithm in iOS' Music.app I have tested it with an iPhone 6s running iOS 10.3.3 and iOS 11 beta 5 and two albums from the iTunes Music Store (iTMS):


Pink Floyd - The Dark Side of the Moon (1973)
Led Zeppelin - Led Zeppelin (I) (1969)


SC = Sound Check

Examples:

Led Zeppelin's song Communication Breakdown (track 7)


Library &gt; Artist &gt; 'Album Title' &gt; Play SC on: Volume is higher
Library &gt; Artist &gt; 'Album Title' &gt; Shuffle SC on: Volume is higher





Library &gt; Playlist&gt; 'SC test LZ' &gt; Play SC on: Volume is lower
Library &gt; Playlist&gt; 'SC test LZ' &gt; Shuffle SC on: Volume is lower
Library &gt; Playlist&gt; 'Sound Check test' &gt; Play SC on: Volume is lower
Library &gt; Playlist&gt; 'Sound Check test' &gt; Shuffle SC on: Volume is lower






Pink Floyd's song Money (track 5)


Library &gt; Artist &gt; 'Album Title' &gt; Play SC on: Volume is higher
Library &gt; Artist &gt; 'Album Title' &gt; Shuffle SC on: Volume is higher





Library &gt; Playlist&gt; 'SC test LZ' &gt; Play SC on: Volume is lower
Library &gt; Playlist&gt; 'SC test LZ' &gt; Shuffle SC on: Volume is lower
Library &gt; Playlist&gt; 'Sound Check test' &gt; Play SC on: Volume is lower
Library &gt; Playlist&gt; 'Sound Check test' &gt; Shuffle SC on: Volume is lower






Pink Floyd's song Brain Damage (track 8)


Library &gt; Artist &gt; 'Album Title' &gt; Play SC on: Volume is higher
Library &gt; Artist &gt; 'Album Title' &gt; Shuffle SC on: Volume is higher





Library &gt; Playlist&gt; 'SC test LZ' &gt; Play SC on: Volume is higher
Library &gt; Playlist&gt; 'SC test LZ' &gt; Shuffle SC on: Volume is higher
Library &gt; Playlist&gt; 'Sound Check test' &gt; Play SC on: Volume is higher
Library &gt; Playlist&gt; 'Sound Check test' &gt; Shuffle SC on: Volume is higher


Note:


The playlist called 'SC test LZ' only contains Led Zeppelin's 1969 album.
The playlist called 'SC test PF' only contains Pink Floyd's 1973 album.
The playlist called 'Sound Check test' contains Led Zeppelin's and Pink Floyd's album.




Additional resources:


iTunes' behavior with Sound Check turned on explained by Bob Katz (Hydrogenaudio forums)
Apple's documentation for 'Mastered for iTunes' (2012) (PDF)