Poor sound quality from ear speaker after replacing screen assembly.

After dropping my iphone and shattering it's screen, the ear speaker seemed to have been damaged as well, with poor sound quality being the indicator. So I purchased the complete replacement display assembly with front camera (which includes the ear speaker). Following the iFixit guide, the replacement went smoothly, however, after completing the repair, the new ear speaker still produced poor sound quality when tested. Improved, but still not as it should sound. I would describe the voice of the person talking on the other end as low and slightly robotic sounding. I proceeded by opening up the phone again and carefully examining the earpiece's ribbon cable with special, magnified, jewlers glasses, but I did'nt notice any damage, defects or possible obstructions. I also made sure to not overtighten the 4 screws that secure the front panel assembly cable bracket.

Any help or suggestions would be much appreciated.