In concert hall acoustics, it's the opposite of reflection; the Sabin is a unit of it
[DOC] [TLE] Springer Handbook of Acoustics: Chapter 9 - CCRMA [PAR] Acoustics in Halls for Speech and Music ... the room, as Sabine did, when he 
carried out his famous ... highly experienced in evaluating concert hall acoustics, 
... if it arrives very soon after the direct sound and/or its ...... loudspeakers are 
often built as six units placed into the ...... opposite reflecting surfaces, as shown 
in Fig.