83.80.163.117
In Reply to: RE: Hmmmmmm... posted by David Aiken on July 03, 2009 at 13:15:55
The intended purpose of that ceiling was to decrease reverberation time, not to absorb the ceiling reflection! Having read what I've read about room acoustics and related psychoacoustics, I note that there is no evidence that early reflections are detrimental and need to be treated, so I will not advise treatment to anyone asking here or elsewhere. One researcher has started a series of experiments investigating the effects of early reflections in real listening environments, but so far the two-channel case has not been investigated:
Naqvi et al., “The active listening room- a novel approach to early reflection manipulation in critical listening rooms”, J. of the Audio Eng. Soc. 2005, p.385
SSF-01 2002 recommends 10 dB, Walker for his Controlled Image Design recommends 15 dB. If you look at Olive's data, at 10 ms perception threshold for a single lateral reflection is at -15 dB (anechoic), -11 dB (IEC room), -12 dB (treated IEC room).
The treshold data for music are from
Schubert (1966), “Detectability of single reflections for music” (Untersuchungen über die Wahrnehmbarkeit von Einzelrückwürfen bei Musik), Technische Mitteilungen RFZ, vol. 10, no. 3, p.124
which, btw. is listed in SSF-01
Note that these data are all absolute thresholds for the single loudspeaker/single reflection case meaning that the mere fact of perceiving this reflection automatically leads to undesired effects so that it has to be eliminated.
The question now is, why use absolute thresholds of a single speaker/single reflection scenario and speech when all of us use at least two loudspeakers, have multiple reflections and listen to music???
I further note, that neither Naqvi nor Schubert are mentioned in Toole's book (of which I have a copy by now).
Klaus
Follow Ups:
Post a Followup:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2009, Audio Asylum, all rights reserved ]
[ Go Green ]
[ Take5 ]