[Paul Spencer]
* COMPRESSION RATIO - Ratio of the driver SD to throat area; Max CR of 2 should be used to be safe unless it is known that the driver can handle more
* EXPANSION CONTOUR - the rate at which the cross sectional area of the horn expands relative to axial length; contours can be mathematically described and are characterised as exponential, hyperbolic, conical, tractrix, etc.
* THROAT - the aperture adjacent to the driver
* MOUTH - the final aperture of the horn device
* BLH - Back loaded horn - a horn in which one side of the driver is horn loaded and the other side is radiating into the (outside) air. Reverse mounting the driver doesn't change a BLH (aka Rear LH) into a FLH.
* FLH - Front loaded horn - the rear radiation of the driver is typically a sealed compression chamber and the front radiation of the driver is horn loaded.
* COMPRESSION CHAMBER - a chamber which is typically sealed which restricts the driver excursion and equalises the pressure on either side of the driver
* CUT-OFF FREQUENCY - this the low frequency limit of the horn / driver combination
* FLARE FREQUENCY - this describes how fast the horn flares; typically close to the cutoff frequency
