The PW-1230DB/DW/SB/SW Plane Wave Speakers features a flat speaker system equipped with "plane wave" units, realizing a narrow directivity pattern by radiating sound from a plane source. Since the Plane Wave Speaker can deliver sound toward a confined target area, it is suited for use in locations such as station platforms and escalator areas that require the broadcast of information announcements, and also in such spaces as museums and art galleries where the reverberation time can be long. A double-sided version radiates sound both backward and forward.