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CHAPTER 19: Reflections, Images, and the... > MEASURING REFLECTIONS - Pg. 568

PART VII Acoustics and Sound Reinforcement 20 10 0 Relative level (dB) -10 Detection thresholds -20 -30 -40 -50 0 10 20 30 40 50 Delay (ms) 60 70 80 Relative level (dB) Mozart Speech Clicks First six reflections in a "typical" room 20 10 0 -10 -20 -30 -40 -50 Second image thresholds: the upper boundary of the precedence effect Mozart Speech Clicks First six reflections in a "typical" room 0 10 20 30 40 50 60 70 80 Delay (ms) FIGURE 19.16 Using data from Figures 19.16 and 19.17, this is a comparative estimate of the detection thresholds and the second image thresholds (i.e., the boundary of the precedence effect) for clicks, speech, and Mozart. The "typical room reflections" suggest that in the absence of any other reflections, the clicks are approaching the point of being detected as a second image. However, normal room reflections would be expected to prevent this from happening because the threshold curve would be flattened (see Figures 19.8 and 19.9).