Provided is a Push-to-Talk terminal having a user interface that makes it possible to immediately verify by sound who has acquired the right to speak at the time of PTT communication. In the step of establishing ohmic contact, a surface of the first electrode is irradiated with laser beams such that arithmetic mean roughness of a surface of the second electrode is not greater than 0. The stimuli are generated at at least partly different times. The value of the coins and the number of coins within each denomination are displayed as the coins are counted. The adjustment portion is adapted for selectively adjusting the receiver in accordance with stored historic observation data. The optical disc with the data protection function has address data different from that used by an optical disc drive system without the erroneous readwrite and erase protection function.