Suppressing early reflections through absorption or angled walls maximizes the initial time-delay gap.

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: Names and explains the ‘controlled-reflection technique’ as deliberate suppression of early reflections to enlarge the initial time-delay gap.
• XREF: Connects to the book’s earlier treatment of initial time-delay gap and early reflections in concert-hall acoustics.