Apocalypse Revealed # 590
590. 13:9 If anyone has an ear, let him hear. This symbolically means, let people who wish to be wise pay attention to this.
To have an ear and to hear means, symbolically, to perceive and obey, and also to pay attention (see no. 87 above). It follows that the verse also means people who wish to be wise.
We are told here, "If anyone has an ear, let him hear," in order that people may pay attention to what goes before. Otherwise they are not wise.