hearing one own sound louder is known as Autophony .
This occurs because of fluid filling in middle part of ear behind the drum.
There is a tube connecting middle part of ear and back of nose which prevents this happening.
this could be because of some allergy.
you can take----
Tab. Mucinac 600 once daily
nose drops 2 drops both nostril 2 times a day for 5 days only
Physiomer normal saline nasal spray
2 puffs both nostril 2 times a day
follow up after 5 days.