Default voice in note 3 does not change automatically

I used to play the voice in whatsapp for example
In note 3
When I touch the top of screen sensor
The voice change from benig loudly to being heared just by the ear and retrun loudly when I do not put it in my ear ot touch the phone above
But now if I put my ear on the sensor above or my hand and move it .. the voice still as if I still puting my hand and never retrun to be loud !
I do not know if u understand me
I am not enabling any motation by the way in my phone