Loudness and room-size was: TV-Mix for Theatre

[Frank Kruse]

I can think of a couple of theoretical reasons that a big room will sound louder than a small room.

I think you misunderstood. I was saying that a given mix sounds way louder in a small room than in a large room even if they are alligned to the identical dbSPL.


frank.

[Frank Kruse]

Well we all know that the physical dimensions of a space are at work here. Within the dimensions, of course, we find direct sound and two type of reflcetive sound; early and late. Listeners in smaller spaces are subject to far more direct and early reflective sounds at a higher rate arrival than in a larger space correct? Therefore the reverberant levels are much higher and may even be additive depending on the frequencies in play.

Yes, but wouldn´t the SPL-meter you allign both rooms with "hear" the sum of all those early and late reflections the same way in both rooms and therefore would give you an according reading? I think every thing you mentioned is also "heard" by the SPL-meter. hm...

I agree that the key to the problem is that an SPL-meter c-weighted slow doesn´t "hear" volume the way a human would therefore they are only able to achieve comparable results in comparable accoustic enviroments.

I have a stack of old-school "Tonmeister-books" but I haven´t found articles about roomsize and felt loudness.

Because abviously we are not able to measure the difference with the methods we use every day.

frank.

[JKD99]

Hi Frank,
Dolby's fine with it (the 84db level). I'm not sure what they do differently in the DMU, if anything, with the fact that we're at 84. I think as long as the 1k tone is correct, then they're OK.
They always check speaker levels, but not usually EQ curves. They EQ'd our stage originally (and for periodic maintenance) though, maybe that's why.

[dr sound]

Frank,
Dolby aligned my room recently. They check the SPL calibration every time we Print Master. To Re EQ the room everytime you Print Master that's crazy. We have digital eq's that are rock solid so every ........ we Re EQ the room . If you must RE EQ everytime you Print Master than there's something messed up with the monitor chain. I take it you Re-EQ BEFORE you mix the Movie? If you Re-EQ AFTER you mixed but before you Print Master, what the hell does that tell you?

[Frank Kruse]

Interesting. Dolby has moved to a rather strickt policy over here with the specs. Monitoring at 7 during the mastering and comments about outrageously loud average levels etc. I guess it´s because the worldwide increase of volume on film soundtracks and theaters turning down their system lower and lower at the same time.

frank.

[Frank Kruse]

Frank,
Dolby aligned my room recently. They check the SPL calibration every time we Print Master. To Re EQ the room everytime you Print Master that's crazy. We have digital eq's that are rock solid so every ........ we Re EQ the room . If you must RE EQ everytime you Print Master than there's something messed up with the monitor chain. I take it you Re-EQ BEFORE you mix the Movie? If you Re-EQ AFTER you mixed but before you Print Master, what the hell does that tell you?

No they don´t re-EQ every time but the dolby-guy does a quick-check of the EQ with his RTA everytime a master is printed to MOD to ID major errors. And since after the mix is before the mix it is as if the stage was alligned for the next one.
As far as I understand it´s part of Dolby´s service to maintain the correct allignment of the system. In the end it´s the producer who´s paying them to tkae care of a correctly alligned dolby-approved theater and masterring process.
And yes I´m aware of the fact that it´s useless to re-allign a stage AFTER the film has been mixed. Luckily I´m not the one who´s resposible for that but I´m still interested in what´s going on.
Oh, and yes the stages are usually alligned before the mix in addition to the verification that is going on before the master is being printed to the MOD.

frank.

[Craig F]

It's not the films themselves but the overly loud previews that they turn down for and don't turn back up for the feature

[Frank Kruse]

Over here trailers can not exceed the LEQ figures. I think 85LEQ for trailers. Wich is still pretty loud, I agree.
But this is kinda off-topic.

frank.

[Branko]

Frank,

I'll try to point out some interesting concepts used in the process of the X-curve creation, hoping that these may answer the original question: why do theatrical mixes sound louder in an equally calibrated smaller room?

There is an interesting article written by Ion Allen (the Father of the X-curve) in one of the recent SMPTE journals (I think Dec 2005) that analyzes the history of the famous "X-Curve". In one section of the article, the author discusses the problem of dialog sounding quieter in a bigger room.
It can be easily concluded from this article that the difference in room RT is the main reason for level differences.
To begin, we should divide signals coming from the loudspeaker into two main groups: short, impulse sounds and long, steady - state ones. Room reverberation affects these two types of sound in a different way, but the general rule is: the longer the duration of the signal, the bigger the contribution of room RT. Music and atmosphere sounds consist of signals whose duration largely exceeds room RT and these benefit from the level build-up caused by room reflections, as the reflection is added to the original signal. Consequently, shorter signals (which dialog mainly consists of) aren't affected that much by the room, as they dissapear before the room reflections start to build - up and there is no superimposition of direct and reflected sound.
Current room calibration techniques use steady state signal - pink noise - for calibration, which leads to a conclusion that this method doesn't "see" shorter signals, thus affecting them in an unpredictable way. The answer to this problem is - experiment, trials and errors, until you find a good relation between levels in different rooms. That's what many of the previous posters on this thread already did, calibrating rooma at 78, 79 or any other value different from 85.
The mixing engineer in a big room will therefore boost shorter sounds (e.g. dialog) in order to balance them with music and atmosphere/ambience/room tones. In a smaller room, the situation is inverted - and the result is lowering the level of shorter signals.
Therefore, the bigger the difference in room size, the bigger the difference in the balance of these two types of sound. Fortunately, todays theatres are far less reverberant than they used to be, so the difference seems to be less.
Coming back to Ioan Allen's article, try to find and read it, as he explains (and understands) these things much better than I do...
Branko

[EarHole]

My room is 15ft wide by 18ft deep with high ceilings. I mix mostly TV ads and find that 78db puts me just about where I need to be.