Mixing the simple present and present continuous in the same sentence

Hi,

The simple past and past continuous have been extensively covered to show how different combinations express different temporal dimensions of the verbs. But this question, focuses on combining the simple present with the present progressive.

Can we mix the simple present with the present progressive in the same sentence? How would that affect the meaning?

1. I relax when I listen to music.

1. I am relaxing when I listen to music.

1. I relax when I am listening to music.

1. I am relaxing when I am listening to music.

Here we have the same set of examples but with different verbs that don’t have any causal relationships between them.

1. I study when he plays.

1. I am studying when he plays.

1. I study when he is playing.

1. I am studying when he is playing.