A method for a surface treatment of a substrate comprises providing a protective layer having a solubility parameter different from that of an adhesive by 1 or less on an bonding surface of a substrate before bonding the substrate with the adhesive. A method includes delivering audio to an ear canal, measuring a residual background noise level within the ear canal, and adjusting the audio based on characteristics of the residual background noise level to maintain a natural audio level. A second seating sensor is disposed at a peripheral portion of the seating region and can detect a second seating position of the occupant. Two hinges is formed on one end of the connecting member. The third balance weight is positioned on the opposite side of the longitudinal axis from the first and the second balance weights.