Horn basics

[slisgrinder]

I need some literature on horn designs because I want to dip my feet at making tapped horn subs. I understand the concept of tapped horns but horns by themselves are eluding me. I realize that horns are usually exponential, but what about something like this or this. They both seem uniformally increasing in area from the throat to the mouth. So do these horns fall under a conical horn design? or is the cross-sectional area of the horn exponentially increasing? I have been looking at this reference and from there:
"Modern horn designs typically feature some form of conical, exponential or tractrix taper. Roughly speaking, the slower the flare rate, the deeper and lower frequencies the horn will reproduce for a given length of horn. For example, a horn area growth rate of 30% per foot will allow reproduction down to about 30 Hz; 1000% per foot (10 times area) per foot provides midrange reproduction; 100 times area per foot is used in high frequency horns."
that is was confuses me...


thanks for any explanation guys...