Enable mono sound on the Apple iPhone or iPad.

Now you’re able to hear all of the sound equally on both right and left speaker channels.

yo note that this setting may not apply if your rig is connected to certain devices.

iPhone Mono Audio Setting

You would want to search for a seperate mono setting on that car stereo or equipment.

Any accessory should honor the setting that is set on Apple unit.

What exactly is mono?

By default, all sound on iOS devices are played in stereo.

That means different sound will play on the left and right speaker.