Sibilance how do I get rid of it?

Stenho, the larger the room past a certain point, the more the delayed soundfield is percieved as a pleasant reverb (in circumstances such as a choir in cathedral), or possibly a discrete echo. It's the delay timing and the number of repeats, among other things, that determines how the soundfield will be perceived, so it isn't a necessarily case of the bigger the room, the worse the effect, at least as far as sibilants go. I don't claim to be an expert (although we have already heard in this thread from one who presumably is - Rives), but I am a musician who has played live in many different spaces and logged a fair amount of studio time, both as a player and a producer, so I have had regular contact with the professionals I mention, in addition to having read books that touch on this subject. The flutter echo will be set up in a room not too large, with parallel hard surfaces and little damping. The short delay time will tend to fold the perceived effect into the initial event, and not be perceived as separate unless one was to stop the music short. You are correct that it will affect all the sounds, not just sibilants, but sibilants are by definition loud transients (which is why they will distort a mic preamp before throat tones, causing pops or hisses which are indicative of clipping), and these will appear to the listener to 'jump out' and smear more noticeably than non-transient sounds. Another factor is that in a typical, more damped environment, it's the higher frequency sounds that are most absorbed, recreating the intended balance of the sound mix, which was made in a damped mixing studio. When replayed in an undamped space, the parts of the music containing proportionally larger HF content (such as transients) will become exagerated in balance. As far as the example of unfurnished homes goes (which of course may contain the right sized rooms to compare with Braab8's problem), I am in these frequently as part of my work, and I have to disagree - I find conversational intelligibility to be greatly affected by such an environment. [I'll even give you a recorded musical example analogous to what I'm talking about: Play (if you have it) the The Beatles' version of Carl Perkins' "Everybody's Tryin' To Be My Baby"; an artificial tape-delay flutter echo has been applied to George Harrison's vocal track, and listen to what happens to the sibilant 'T's and 'S's as he sings the title line in the choruses.] Again, I stress that I am not trying to cast doubt on anything said above in this thread, but just to point out that in all probability those other potential culprits will be having a lot of their possible effects swamped by that of this room in its current state. In other words, had Braab8's system been set up in a carpeted furnished living room instead, we probably wouldn't be having this debate right now.

Where to begin?? Well first I don't think anyone would argue that siblance can be caused from poor (on sometimes purposely done--as Zaikesman points out) source material. What can you do about this--nothing. Siblance can also be caused by poor source components (or D/A conversion). Siblance can be caused by poor power that affects one or more of your components. However, in this case, it seems clear that the majority of the problem and the first place to attack it is the room. After that, you may begin to attack the other areas, but it's not going to do much good until you get the big problem fixed first.

Stehno makes an interesting point about how we perceive sound. We have done a lot of research in psycho acoustics and it's a very interesting topic. Not many do this type of work and it's not often published since there is little funding on it. We are exploring new avenues in this area and are finding that perception is dominant in listening environments over steady state measurements, but fortunately the 2 do correlate.

As Stehno states, we know when we are in a church or empty space and compensate for that. That is psychoacoustics, and he is right. The human ear has the ability to distiguish reflected tones past 35 milliseconds or so as separate from the original tone. When the reflection arrives at the ear within 35 milliseconds we can not distinguish it (for the most part) and integrate it as part of the original tone. These short time reflections add to ambiance and general spaciousness of the soundstage. The longer the reverberation times the larger the space. The louder the reverberation the emptier the space. People could walk into a space blindfolded and have someone talk to them and could give a rough estimate of the size of the space and whether it was empty with hard surfaces or not.

Now, that being said, our hearing compensation is that to tune out those later reflections past 35 milliseconds (and much longer in large spaces) and we attribute that to the noise floor. Peter D'Antonio of RPG has done a very interesting auralization of this. He has done it for many buildings, but for one it was an entry way into an office building or hotel I believe. The auralization has several voices speaking in the background and then one that is louder--speaking to you. Without room treatment the intelligibility of that speaker is very poor as it is masked by all the other voices reverberation around you, but once the room is treated the intelligibility goes way up. This might seem very obvious, but it makes an important point. Long time reflections must be attenuated or they impede on the intelligibility of the original sounds being produced. This directly translates to music, but is even more important, because we are listening critically to details including very low level and short timing cues. When reverberations of other sounds are lasting too long, they are masking those details. The reverberations longer than say 50 to 60 milliseconds will come across as sibilance.

While its true that the human ear can percieve/distinguish between the original and reflected energy the two become interrelated in different ways. A sound wave will bounce around a room an average 60 times (RT-60) before becoming inaudible (as Rives said). HIS ROOM (Braab8) is probably more like 70 to 90 times before becoming inaudible. These reverbrant sound waves bouncing around the room will do two hideous things 1) it places a certain amount of "strain" on the brain trying to decipher between the original and reflected signal(a lessening enjoyment of the musical experience) and 2) the sound waves can then crash into each other, reflected waves crashing into the original waves. This can cancel detail so that the original signal doesn't make it from the speaker to your ears unaltered. This is the summation/peaks and cancellations/nulls called Phase distortion as it pertains to room acoustics.
"Long time reflections must be attenuated or they impede on the intelligibility of the original sounds being produced" (Rives)
It happens in more deceptive ways in the higher frequencies since its not simply a matter of calculating room nodes which pertain to the lower frequencies (e.g. their wavelengths being of direct significant proportion to the room). To throw on a 3) point--regardless of how flat the speakers freq. response may be, the reflected envergy can easily become colored/unbalanced based on how the room absorbs certain freq. and reflects others and its overall dimensions. High frequencies get colored up too. I know I'm regurgitating a little now. (Lastly, I find AC conditioning to be junk in most respects. There's some foundation to it, but not enough to deserve anywhere near the level of attention it gets in the marketplace--especially compared to room treatment products.)

Correction on RT=reverberation time
http://www.mcsquared.com/reverb.htm

Your erudite responses are appreciated. And I certainly don't want to be obtuse here. However, I do not believe that you have provided one real life experience where sibilance was present and then disappeared or vice versa.

In fact, I was at the Kansas City zoo today with my family. At one point we were in a large (approx. 13H x 25L x 18W) concrete walled room with an aquarium glass wall taking up about 2/3rd's of one of the long walls. As my wife was speaking to me from about 3 feet away and I paid close attention to her pronunciations. There were only 3 other people in this mostly empty room. Her s' sounded just fine. Both in the actual and the reverb. Just as I suspected. My wife's pronunciation did not change one iota.

As I stated in an earlier post. I ran a test (for other reasons) by taking out the amplifier's in-line power conditioner and ran the romex straight from the service panel to a cryo dipped hubbell 20 amp IEC plug and plugged it directly into the amplifier. The sibilance was very present and was the most notable difference. Enough so where I was anxious to put things back to the way they were. And I know how much the sibilance increases when I remove all 3 in-line conditioners since I did not always have them.

You guys can hypothesize all you want but I am not buying it.

Perhaps when Braab8 resolves his issue or begins the process of elimination, s/he will update this post.

Besides I already know I'm right otherwise I would have changed my opinion at least 3 posts ago.

:)

-IME