Can I listen to instrumental music for relaxation?

I know music is haraam. I am working with Arabs around me. I happened to come across one of my senior colleague and he was watching a picture slide shows of gardens, sea water, landscape beautiful pictures and there was light background music going on. My other friend objected and said you are listening to a music which is haraam. But he replied, not all music is haraam, light music which gives you relaxation to your mind is not haraam. He further replied that he is not watching any lady dancing, nor I am dancing. It just relax my mind. Hence it is not haraam. Please advice a background music soft one with a instrument like flute, violin or any soft equipment likewise which appears to give relaxation to mind is allowed or not. Here we are not talking about our inner soul. As relaxation to inner soul is only by zikr and nothing else.