Speaker Problem Coolpad Quattro

the in call speaker has stopped functioning.   THe recipeient of my calls can hear me speaking but i cannot hear them.   All other sounds on the phone are functioning properly.  Also,  When I tried putting the phone in speakerphone mode, It was the same scenario, meaning  I still could not hear the person on the other end of the call while they still could hear me.   I am somewhat puzzled why this is the case and if there is some solution