You can use either. The greater the separation between the sounds introduced into each ear, the stronger the Hemi-Sync® effect. We generally recommend using earphones for experiential exercises, because earphones maximize the sound separation and tend to block out exterior noise. Speakers are also fine, and in fact may be preferable when you are playing Metamusic® or other nonverbal titles as background while engaged in another activity. Be in the same room as the speakers. To enhance the separation between the sounds, it is recommended to position yourself between the speakers, when possible.