Abstract: Electroacoustic apparatus for reproducing lowest to medium frequencies being provided with a housing wherein a folded exponential horn combined with a loudspeaker is defined having five horn element walls lengthening the horn with good exponential form toward its throat and bent horn element walls provided in the area ending in the horn mouth and at foldings above the mouth and forming the horn with high approximation to an exponential function. The horn element walls are arranged so that undesired reflections are substantially avoided and no sharp break points exist in the course of the horn which is advantageously prolongated toward its throat, and a high characteristic acoustic impedance as well as a linear frequency reproduction characteristic over a wide range are achieved.