A receiver for receiving both GPS signals and GLONASS signals is provided. The first and second surfaces of the sheet are simultaneously irradiated with monopolar ion clouds substantially opposite to each other in polarity generated from the ion-generating means. Also disclosed is a method for evaluating or treating a patient for hypernasality or nasal air emission during speech using the above device. The sum of the focusing error signals relating to the main beam and first sub beams is a final focusing error signal.