Binaural means that both ears are addressed. Slightly different frequencies are played on both ears via headphones. As early as 1839, the German physicist Heinrich Wilhelm Dove discovered that this creates certain vibrations in the human brain. Depending on the frequency range, such oscillations influence a person's mood. Thus, a distinction is made between delta (dreamless sleep), theta (light sleep, deep relaxation), alpha (relaxedness, relaxation, memory, imagination), beta (waking consciousness, perception, thinking, logic, everyday life) and gamma frequencies (meditation, focus, concentration, creativity, learning). In hypnosis, such binaural frequencies can also be played, for example, to deepen relaxation and thus better enter the trance.