A method of determining recommended positions for sets of electrode elements on a person's head, the method comprising: simulating affixation of a first set of electrode elements to one, right side of the person's head at a first plurality of positions; simulating affixation of a second set of electrode elements to the other, left side of the person's head at a second plurality of positions; simulating application of an alternating voltage between the first set of electrode elements and the second set of electrode elements at each of the first plurality of positions and each of the second plurality of positions, respectively; determining, based on the step of simulating application of an alternating voltage between the first and second sets of electrode elements (41,42), an alternating electric field in the person's brain for each of the first plurality of positions and the second plurality of positions; and outputting, based on the step of determining results from the first and second pluralities of positions, a recommended position for the first set of electrode elements and a recommended position for the second set of electrode elements, wherein the recommended positions for the first and second sets of electrode elements (41, 42) are output as a display or printout; characterized in that: the first set of electrode elements have a first, upper section for positioning above the external opening of the ear canal in the one side with an orientation that is predominantly horizontal, and a second, rear section for positioning behind the external opening of the ear canal in the one side with an orientation that is predominantly vertical; the second set of electrode elements have a first, upper section for positioning above the external opening of the ear canal in the other side with an orientation that is predominantly horizontal, and a second, rear section for positioning behind the external opening of the ear canal in the other side with an orientation that is predominantly vertical; and the step of determining results from the first and second pluralities of positions determines which of the first and second pluralities of positions results in an alternating electric field in the person's brain with high uniformity.! simulating affixation of a first set of electrode elements to one, right side of the person's head at a first plurality of positions; simulating affixation of a second set of electrode elements to the other, left side of the person's head at a second plurality of positions; simulating application of an alternating voltage between the first set of electrode elements and the second set of electrode elements at each of the first plurality of positions and each of the second plurality of positions, respectively; determining, based on the step of simulating application of an alternating voltage between the first and second sets of electrode elements (41,42), an alternating electric field in the person's brain for each of the first plurality of positions and the second plurality of positions; and outputting, based on the step of determining results from the first and second pluralities of positions, a recommended position for the first set of electrode elements and a recommended position for the second set of electrode elements, wherein the recommended positions for the first and second sets of electrode elements (41, 42) are output as a display or printout; characterized in that: the first set of electrode elements have a first, upper section for positioning above the external opening of the ear canal in the one side with an orientation that is predominantly horizontal, and a second, rear section for positioning behind the external opening of the ear canal in the one side with an orientation that is predominantly vertical; the second set of electrode elements have a first, upper section for positioning above the external opening of the ear canal in the other side with an orientation that is predominantly horizontal, and a second, rear section for positioning behind the external opening of the ear canal in the other side with an orientation that is predominantly vertical; and the step of determining results from the first and second pluralities of positions determines which of the first and second pluralities of positions results in an alternating electric field in the person's brain with high uniformity.! the first set of electrode elements have a first, upper section for positioning above the external opening of the ear canal in the one side with an orientation that is predominantly horizontal, and a second, rear section for positioning behind the external opening of the ear canal in the one side with an orientation that is predominantly vertical; the second set of electrode elements have a first, upper section for positioning above the external opening of the ear canal in the other side with an orientation that is predominantly horizontal, and a second, rear section for positioning behind the external opening of the ear canal in the other side with an orientation that is predominantly vertical; and the step of determining results from the first and second pluralities of positions determines which of the first and second pluralities of positions results in an alternating electric field in the person's brain with high uniformity.!