An improved throat (2) for transmitting acoustic energy from a source
driver
unit (7) to a feeder section (3) of a directivity controlling acoustic
horn is disclosed. The throat (2) comprises: a circular throat entrance
(2i) connectable to the source driver unit (7); a rectangular
throat exit (2e) connectable to or integral with the feeder section
(3); and a circular cross-section to rectangular cross-section transition
portion (2a) extending between the throat entrance (2i)
and the throat exit (2e). The throat (2) is shaped such that
its profiles initially diverge from an axis longitudinal to the throat (14)
at the same angle in a direction from the throat entrance (2i) towards
the throat exit (2e). Such a throat, when fitted in an appropriate
acoustic horn with a source driver unit having a taper matching the aforesaid profile
angles, provides a smooth transition for sound waves propagating out from the source
driver unit into the horn.