Hello guys

,
I got a sony ericsson w810i. The problem is ...if i get a call and answer it on my phone(without the headphones) the sound volume is very very low

. If i am travelling or in a noisy place i cant hear a thing. But if i put on my headphones the sound is proper. I had earlier used changed my acoustics....forgot which one i added. Could this problem be because of the acoustics? Is they any way to increase my earpeice volume?.
Thank You.