Hi Pradeep,
I have over 30yrs in policing, but new to flying - but radio communications in both fields are similar. When I first went on the road I couldn't understand what was being said. For the first few weeks I think I drove my then senior "buddy" mad with saying "What did they say?"
I think part of the problem is the way radio changes the voice tonal range slightly and adds other backgound noise/static, etc, in. After a while your ear (brain) will become tuned to this and you'll understand it much better. I found I did after a few weeks.
One thing may help to tune your ear in - if you have access to a radio scanner - tune it to the local airport and listen to the communication chatter. You'll find that within a short time you will start to better understand what is being said.
Using the scanner lets you listen in when you are relaxing at home (hearing this type of communication more often), rather then just when you are in the aircraft and concentrating on other things - like flying.
Hope this may help?:thumb_up:
Regards,
Paul