Our brains create different rhythms and patterns constantly. These patterns and activity move up, down, and all around in reaction to what is being heard, thought, and felt. Usually there is one dominant thought or action, with many other active functions at various levels of background. Imagine hearing a complex chord played on an instrument: you may focus in on just one pitch, but you are hearing and processing all of the notes no matter how many are played.
One of the goals of meditation is to quiet and control the brain activity to allow for deep relaxation meditation and higher spiritual consciousness. This is accomplished by training the brain to respond in a predictable way to a consistent stimulus or process. A single tone brain entrainment is like hearing just the one dominant pitch of the chord. But adding dual tonality opens up the meditation training exercises so that the brain can process complex activities in an organized way.
To achieve the most effective level of meditation, theta meditation, it is important to utilize a guided meditation download that includes dual tonality brainwave entrainment. The Successful Living Series title The Spiritual Mind Enhancer provides guided meditation training that is specifically focused on achieving the theta meditative state.