The Importance of Room Interaction

Recently I purchased the Pulse dvd, I already have the Pulse cd for comparison. Using 640 kbps Dolby Digital and the song 'Comfortably Numb', on first spin of dvd I had the volume matched low to what I usually play the cd at. Although the dvd has much more resolution at this volume, the guitar on this song did not have the siren effect that I have grown acustom to on the cd.
Today I played the dvd again at approx.95 decibels 'A' weighted 105 'C' weighted and there it was, the siren effect. I attribute this to sound interaction with the room at this high volume. Also at this volume I find directionality of the speakers less obvious.
I realize of coarse that not everyone can crank their stereo this loud and your room acoustics will be different than mind. But for me I like music at a higher volume just for the room effect which is similar to how I recall a Live concert sounding at our auditorium.

Your description sound a lot like slap echo occuring in your room at higher volumes.:ihih:

Nooo,it's not slap echo effect, I've been in rooms like that.
On 'Comfortably Numb' its the way he plays the solo that creates this siren effect, and its at a higher freq. At a lower volume the sound isn't bouncing off the walls enough to notice.I imagine the people who were at the concert noticed this effect as well which is what makes this solo so awesome.
On other songs with high frequency notes, I would discribe the effect as halographic. But on other songs at high volume the sound is very lively.
Most people that have listened to my system can't handle music this loud. And stereos that I've heard other than mine will be start to distort and sound harsh when cranked.
What I am trying to say is assuming you have a good equipment and good room acoustics. Acheiving good sound wave interaction in the room is vital. For me this happens around 95 decibels.

This is why i have ALWAYS bought first reflection point absorbers ans bass traps and now spend close to 6K on a real digital room correction system and modify my room.

Acoustics are just as important as speakers.

Did you compare the DVD with the CD using just the two-channel versions? If the DVD track was originally done in 5.1 and mixed down to two-channels by your DVD player or receiver, then the two-channel mixdown audio is going to have very different balances between the different sound elements, especially for those sound elements that got steered into the surround channels. During the two-channel mixdown from 5.1, those elements that bridge both the main and surround will overlap with one another and potentially drown out those sounds more anchored to the front soundstage.

And even with a dedicated two-channel mix, the producers might have chosen to remix that track as well, which would make the CD and the DVD sound somewhat different as well.

I'm not sure what you're talking about when you refer to the "siren effect". If you hear this only at very high levels, then it might be something in your room hitting a resonant frequency, especially if this phenomenon only occurs in your room and not elsewhere, like in your car or at your computer. Room treatments might not help in this case without knowing the origin.