Early reflections must be suppressed about 15 dB to stay inaudible

Evidence

A lot of effort and talk goes into getting the right acoustical setting for the loudspeakers, but little, it seems, for the listener. Just today I was perusing a high-end audio magazine, and saw a photo of a reviewer’s listening room. My first impression was that it was probably not a bad room: the loudspeakers were well away from the boundaries, the walls were geometrically irregular with many large shelving units full of books and recordings, and there was what looked like a good carpet. But, the solitary chair was very close to the back wall. It is an unfortunate fact of many home listening rooms, and I have experienced it in some hotel room audio-show demonstrations. The ideal solution is to move the listener away from the wall, but with limited space this may not be possible. Figure 9.15 shows what happens; a whole new set of reflections is created, and the ones immediately following the direct sounds from the loudspeakers are very early and very strong. There will be ceiling reflections as well. — , Toole, Floyd E - Sound reproduction-…, 1117 (#exemplifies, via linked claim)

Categorization

• XREF: connects to: First reflections must arrive within 30 ms to avoid being heard as echoes — David Howard, Jamie Angus, coustics and Psychoacoustics, 742; ASW depends most on mid-frequency reflections within the first 80 ms; In small rooms RT target 0.2-0.5 s; early reflections dominate mid-high frequencies (+1 more)

Related

• Near-wall listening positions create early strong rear reflections (similarity 0.92)
• A small listening room’s first reflections mask the recorded acoustic space (similarity 0.91)
• Listening seats placed near rear walls create early strong reflections that degrade imaging (similarity 0.89)
• In small rooms RT target 0.2-0.5 s; early reflections dominate mid-high frequencies (similarity 0.88)
• Room boundary reflections are the second loudest sounds a listener hears (similarity 0.87)
• Early reflections must stay below roughly 15 dB to avoid blurring a stereo image (similarity 0.87)
• Removing conflicting reflections improves perception of low-level audio detail (similarity 0.87)
• Early side-wall reflections range neutral to beneficial with well-designed loudspeakers (similarity 0.87)
• Small playback rooms impose their own early reflections on recorded sound (similarity 0.87)
• Sitting close to a rear wall creates early strong reflections that corrupt perceived sound (similarity 0.87)
• Early wall reflections pin perceived sound space to room size (similarity 0.87)
• First reflections must arrive within 30 ms to avoid being heard as echoes (similarity 0.87)
• In small rooms reflections arrive early and never form a diffuse field (similarity 0.86)
• Natural room reflections are too weak and early to please listeners of reproduced speech. (similarity 0.86)
• Early lateral reflections are attenuated by loudspeaker directivity, not harmful. (similarity 0.86)

Broader Connections

• ASW depends most on mid-frequency reflections within the first 80 ms #expands (0.78)
• In small rooms RT target 0.2-0.5 s; early reflections dominate mid-high frequencies #expands (0.75)
• Listening seats placed near rear walls create early strong reflections that degrade imaging #exemplifies (0.75) — , Toole, Floyd E - Sound reproduction-…, 1117