Acoustical impulse response functions of music performance halls, c2013, via WWW, Sept. 12, 2013: PDF t.p. (Douglas Frey; University of Calgary) p. 89 (professional sound and electrical engineer residing in Calgary, Alberta, Canada; his company, DFI Technology Ltd.; B.Sc. and M.Sc., Department of Electrical and Computer Engineering, University of Calgary, 2003 and 2010, respectively; BMus, University of Calgary, majored in composition and orchestration)