So I'm breaking these out into their constituent links - three links in a row with no intervening text makes it hard to know that there are three links there with the way vBulletin formats links here in either of the themes
For those who want to know how volume factors in here are a couple of links:
Precedence Effect
this is a very good explanation of what Haas observed and described - it is the inter-aural time delay that determines how we determine direction of a specific sound, i.e. the time delay between a sound hitting the pinnae of one ear and hitting the pinnae of the other - the times will be something of the order of 1-50ms and there will be a slight drop in perceived loudness, which is usually less than 10db down.
The experiment he conducted required listeners to first identify which of two speakers was delayed and to then raise the intensity of that speaker so that there was no perceived delay: listeners would increase the level by up to 10db when the signal in that speaker was delayed near 50ms.
So, we see where this 10db figure you allude to earlier comes in, this time as an increase in intensity as a compensation for perceived delay - not a mix situation but a room design and, more importantly, sound reinforcement system design parameter, allowing for smooth inclusion of speakers around a room that do not precede the main source but reinforce it by delaying the signal so that it is in sync with the primary source.
The opening post was an interesting read and clearly states the case for using your ear rather than your eyes and trying to interpret data that is otherwise not impacting on the quality of your sound.
There is then the statement from F Toole, PhD, (relayed by the filtered perception of the poster) that you should be considering spectral energy/time rather than amplitude/time within room design considerations - note that this is not directly aimed at mixing but on improving room acoustics within which a mix is done.
The references to F Toole, PhD's comments and discussion in relation to room reflections is interesting and highlights how a single study can impact an entire field without anyone either replicating the study or worse still misinterpreting the results and subsequent conclusions of that study. This happens in many fields where folks can't be assed to redo an experiment - forgetting that the first part of accepting a result from any experiment is that it is reproducible; the result can be that many people build further theories based on something unproven and then wonder why it all falls apart when it comes time to test their theories in an unbiased experimental regime - they have built their theories on potential falsehoods and so when testing begins the falsehoods shine through and pull the theory down with them.
The discussion then moves on to highlight a specific room and the data associated with it and the impact of the speakers within the room - highlighting acoustic issues with the room design or more likely issues with the speaker (there is no conclusive proof offered that either is the actual problem).
There is passing reference to the Haas Effect and other well-known JND (Just Noticeable Differences) and the impact of high energy spikes having the ability to mask lower energy material for up to 30ms (this is the basis of the band-compression technology within the MP3 codec).
I again see where you get your 10db figure from (it is talking about first reflections being damped down by 10db or more): this post is talking about in-room reflections, not mix levels; and so the numbers do not apply either to the mix situation in general or the Haas Effect in particular,
another piece on room design and treating reflections and other issues.
The Haas Effect is once more addressed in passing and offers some interesting misinterpretation of Haas's PhD conclusions, that sounds should 10db down on the delayed signal for them to not interfere with the perception of direction - this is a total misrepresentation as the level at which a sound is perceived to be lower is based on the inter-aural time delay, not on actual intensity received at either ear. that is, the perceived delay will impact perceived intensity and so no alteration to intensity is required to achieve the Haas Effect in a mix situation.
Final thoughts and comments
Of the three links, the first provides us with the best explanation of the Haas Effect and what it was related to in terms of its initial application to sound reinforcement. The other two are discussions about room design and room treatment and the Haas Effect is a passing if meaningless contribution to the discussion,
The application of the Haas Effect to creating a pseudo stereo placement within a stereo field does not require the application of a 1-10db boost to the delayed signal.
It does not require any direct manipulation to the intensity of either side of the signal, the delay time provides that intensity drop on its own.
The Haas Effect is about direction perception based on timing differences alone. Take a mono signal and split it, send one side to the preferred channel panned hard to that channel; delay the other side and send it hard panned to the other channel the longer the delay the more the sound pops out of the other channel and the further across the stereo field it is perceived to be. Delay times longer than 50ms are not likely to arise often, so limit your delay time range to be between 1ms and 50ms
