A device for determining and controlling a bale length on a pick-up baler for agricultural harvested material has a pick-up device, a feed channel connected to the pick-up device, and a pressing channel with pressing piston connected to the feed channel. The provided electrets transducer includes a solar power supply device, an amplifier circuit having a first input terminal coupled to the solar power supply device and a second input terminal coupled to an audio signal input terminal, and an electret loudspeaker coupled to an output terminal of the amplifier circuit. The conductive paste comprises main components including a metal powder, a glass frit, and an organic vehicle. Left and right sidewalls defining each groove are provided, at their leading ends, with temporary locking parts restricting slipping of the wire harness out of the wiring groove. The data input circuit may include a first delay unit for delaying the data in order to match setup-hold time, a second delay unit for performing delay for adjusting the data outputted from the latch unit, and a third delay unit for performing delay for adjusting the write strobe signal outputted from the latch unit. In one embodiment, information about the changing shape of the human oral cavity may provide information useful in determining the nature of a person’s vocalizations for speech recognition purposes.