Purchase and download some audio editing software such as Adobe Audition or Garage Band. These programs will allow you to open up music tracks and songs and edit them in a variety of ways.
Open the program, then load the song into the program. Click File and Save As and save the song as a .wav file.
Click in the left speaker channel in the program and drag your pointer across the entire left channel, highlighting it. Click Edit and then Copy. Paste the left channel into a blank channel. Repeat this process for the right channel as well.
Highlight the left channel and invert the file by going to the Process menu and choosing Invert.
Open up the Parametric Equalizer menu and adjust the low-frequency shelf down to 200 Hz. Repeat this process for the right channel.
Choose the Create Mixdown option to blend the two channels back into one file, and save it as a .wav or an MP3.