Q: voice issue iphone 6 plus ios    8.1.2

I have an voice issue with my new iphone 6+ which i bought 2 days back . Sound is not clear and not able to hear voice from other side correctly . Voice is not loudly and not able to increase it .  And if i put the call in loud speaker , incomming voice is clear to me , but other side they are feeling like my voice from a long distance  . I think this issue came after i updated to OS 8.1.2

Any help for this .