Controlled-reflection technique maximizes initial time-delay gap by suppressing early reflections

Evidence

One way of achieving this is to use absorption, as shown in Figure 7.21. The effect can also be achieved by using angled or shaped walls, as shown in Figures 7.22 and Figure 7.23. This is known as the “controlled-reflection technique” because it relies on the suppression of early reflections in a particular area of the room to achieve a larger initial time-delay gap. This effect can only be achieved over a limited volume of the room unless the room is made anechoic, which is undesirable. The idea is simple: by absorbing or reflecting away the first reflections from all walls except the farthest one away from the speakers, the initial time delay gap is maximized. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2286

Categorization

• DEFINE: Defines ‘controlled-reflection technique’ and the ‘initial time-delay gap’ it exploits.

Related

• Early reflections must arrive within 20 ms or they are perceived as echoes. (similarity 0.84)
• Early reflections must be suppressed about 15 dB to stay inaudible (similarity 0.82)
• Removing conflicting reflections improves perception of low-level audio detail (similarity 0.82)
• Suppressing early reflections in one listening zone widens the perceived time-delay gap (similarity 0.82)
• Music listeners prefer reflections far stronger and later than small rooms provide. (similarity 0.81)
• First reflections must arrive within 30 ms to avoid being heard as echoes (similarity 0.81)
• Real-room reflections are attenuated and delayed, not equal-level and immediate. (similarity 0.81)
• A 0–30 ms gap before first reflections cues spatial size while avoiding echoes (similarity 0.81)
• The direct-to-reflection gap must stay under 30ms or become audible echoes. (similarity 0.81)
• Early wall reflections pin perceived sound space to room size (similarity 0.80)
• True envelopment needs reflections delayed beyond 80 ms, impossible in small rooms alone (similarity 0.80)
• Lateral early reflections arriving within 20 ms create perceived spaciousness (similarity 0.80)
• Side-wall reflections aid spatial impression while front and rear early reflections do little (similarity 0.80)
• Initial time delay gaps of 8-20 ms are naturally achieved in most rooms (similarity 0.80)
• Redirecting reflections creates uneven hot areas, so absorption is often chosen. (similarity 0.80)