A vehicle for transporting a payload over a surface that may be irregular and may include stairs. The sound source used is a highly directional parametric loudspeaker. A flexible plate is mounted in planar contact at the side of the upper cavity apertures on the microtitration filter plate. The resistive loads are arranged to minimize thermal noise, while the regulated cascode circuit is arranged to increase the output impedance of a current mirror The increased output impedance results in higher DC gain in the operational amplifier. A synthesis unit 60 generates a second control voltage Vdrv* obtained by adding to the feedback voltage Vfb a voltage according to a sum of the feedback current Ifb and the feed forward current Iff. The subsea connector comprises a first portion and a second portion, means for connecting the first portion and the second portion, and means for rotationally aligning the first portion and the second portion.