crwdns2933897:0crwdne2933897:0

What's the third pin for iPhone 13 loudspeaker for?

I'm doing a DIY project that will use iphone 13 pro speaker module, but it has 3 pins. and assuming from the sound i got with just a left and right cable, third is "middle speaker" wire? Or what's the third smaller pin on top for?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2853045:0crwdne2853045:0 crwdns2853046:0crwdne2853046:0
crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0