It’s always important to fully test a device before attempting a repair. If you don’t do this, then you’ll never know if the problem was pre-existing or if it was caused by faulty replacement parts or mistakes in the repair itself. It’s not clear if this is a repair you were asked to do for a customer (or friend/family) or if you are buying/selling used phones. It doesn’t change the problem but it does affect solutions moving forward.
Start by re-installing the original screen to see if the problem is consistent or not. While you’re at it, double check your work by following this guide. Take a close look at all the flexes; you want to see if there are any tears (however small) or damage to the connectors. Also insure that all of the connectors are properly seated because the ear speaker and loudspeaker are on completely different flexes but the connectors are relatively close to each other on the logic board.