In a surround headphone output signal generator for generating multichannel sound signals from digital audio data, and combining the sound signals for the respective channels to generate two-channel surround headphone output signals for outputting to headphones, a DIR 10 detects from the digital audio data a sampling frequency included in the digital audio data concerned. The filter batting is then passed through a manufacturing device, which slices the batting in the vertical as to create two continuous filter batts from the parent filter batt. The electric line or lines extend through the spaces and extend along the surface of the route in andor about the travelling direction of vehicles.