We here at District Remix not only love music, but sound design. There are so many layers to make the magic that happened in A Star Is Born's set with the sound.
First, you have to capture and control all the audio that you get from the concerts they recorded at. Oh yeah, they got to spend a few minutes in between acts to film the concert scenes. They filmed at the Stagecoach, Glastonbury, and Coachella festivals.
Bradley Cooper and Lady Gaga both sang live while filming, versus lip-syncing to a audio track. This allowed for much more real and convincing performances, but also made some challenges as the backing instrumental tracks had to be matched up to them.
Next, the sound mixers have to take everything, from the dialogue and singing, plus the sounds from the backstage, on the stage and crowd, and blend it together seamlessly so that you can understand every word the actors say, but not losing the background. Certain sounds that can't be captured on set, such as footsteps and extra crowd noise are added in later.
And then all of this is mixed in Dolby Atmos, the latest in immersive sound design for film. Instead of just having certain sounds come from the front and others the side, Dolby can now take individual sounds and place them anywhere in a theatre to create a truly engulfing sound that reflects what is on screen.
The end effect in the theatre is incredible! Make sure to watch A Star Is Born!