Sakari Tervo Jukka Pätynen Tapio Lokki Acoustic reflection path tracing using a highly directional loudspeaker. 245-248 2009 WASPAA http://dx.doi.org/10.1109/ASPAA.2009.5346530 conf/waspaa/2009 db/conf/waspaa/waspaa2009.html#TervoPL09