"... why so few threads on acoustics?"
Room acoustics can be a fairly complex subject... and imo if we’re talking about home audio, the speaker’s radiation characteristics and setup also come into play - in other words, it’s not just about the room.
" Unless you are sitting nearfield, there can be more energy in reflections than directed.... guess what reflected energy does to timing? "
The first part of that statement I agree with: Typically there is considerably more energy in the reflections than in the direct sound.
The second part implies that reflections ruin the timing cues. Imo this depends on when they arrive, their spectral content, and their arrival direction.
Very early reflections (those arriving within about .68 milliseconds of the direct sound) are the most likely to affect imaging precision, but they can also affect clarity. These are more likely to be loudspeaker diffraction and/or reflection artifacts than room artifacts.
Again with imaging and clarity in mind, note that Linkwitz recommends avoiding room reflections within 6 milliseconds of the direct sound, while Geddes recommends avoiding room reflections within 10 milliseconds of the direct sound. According to Geddes and Griesinger, early reflections in the vertical plane are more benign than those in the horizontal plane.
So assuming room size and/or speaker characteristics and placement do not prevent early reflections, what should we do about them? Ignore them, absorb them, diffuse them, or reflect them away from the listening area? I’m not sure there is a "one size fits all" answer.
Incidentally the above implies that RT60 falls short as a metric of room acoustics, as (for starters) it tells us nothing about what’s happening in those first several milliseconds.
Duke
Room acoustics can be a fairly complex subject... and imo if we’re talking about home audio, the speaker’s radiation characteristics and setup also come into play - in other words, it’s not just about the room.
" Unless you are sitting nearfield, there can be more energy in reflections than directed.... guess what reflected energy does to timing? "
The first part of that statement I agree with: Typically there is considerably more energy in the reflections than in the direct sound.
The second part implies that reflections ruin the timing cues. Imo this depends on when they arrive, their spectral content, and their arrival direction.
Very early reflections (those arriving within about .68 milliseconds of the direct sound) are the most likely to affect imaging precision, but they can also affect clarity. These are more likely to be loudspeaker diffraction and/or reflection artifacts than room artifacts.
Again with imaging and clarity in mind, note that Linkwitz recommends avoiding room reflections within 6 milliseconds of the direct sound, while Geddes recommends avoiding room reflections within 10 milliseconds of the direct sound. According to Geddes and Griesinger, early reflections in the vertical plane are more benign than those in the horizontal plane.
So assuming room size and/or speaker characteristics and placement do not prevent early reflections, what should we do about them? Ignore them, absorb them, diffuse them, or reflect them away from the listening area? I’m not sure there is a "one size fits all" answer.
Incidentally the above implies that RT60 falls short as a metric of room acoustics, as (for starters) it tells us nothing about what’s happening in those first several milliseconds.
Duke