The present invention relates to the use of a hydrophilic membrane to provide by the process of pervaporation through the membrane water suitable for agricultural irrigation, industrial use, hydrating or rehydrating of food or agricultural or pharmaceutical compositions. The apparatus further includes a main stage configured to obtain the plurality of output audio signals and further to obtain, as a virtual position for each output audio signal, the loudspeaker positions, and to generate the number of loudspeaker signals for the loudspeaker array such that the loudspeaker positions are replicated as a virtual sources by the loudspeaker array. A diameter d in micrometers of an exposed contact pad area of the second contact pads satisfies d\u2267x+142 \u03bcm, where x is a pitch of the second contact pads in micrometers.