Complex sentence: The enclosure or driver must have a small leak so internal and external pressures can equalise over time, to compensate for barometric pressure or altitude-the porous nature of paper cones or an imperfectly sealed enclosure is normally sufficient to provide this slow pressure equalisation.
Split into simpler sentences: The enclosure or driver must have a small leak so internal and external pressures can equalise over time, to compensate for barometric pressure or altitude. The porous nature of paper cones is sufficient to provide this slow pressure equalisation.