Fader adjustments from trailer to feature

[Randy Stankey]

...your ears will get used and ‘dampen’ such soundtracks where it’s loud-loud-loud all the time. ...

One of our patrons at Mercyhurst was an otolaryngologist ("E.N.T." doctor) and I had a couple of conversations with him about how the body reacts to sound. He told me that there are muscles inside the ear that can alter the tension of the eardrum, making the ear more or less sensitive to sounds, in order to protect hearing from excessively loud sounds. After a period of time, these muscles can stiffen the eardrum, making it less sensitive. When the loud sound goes away, the eardrum is relaxed, restoring normal hearing.

He told me that one of the biggest dangers to hearing is impulse noise. Loud sounds that occur over a short duration don't give the eardrums time to react and protect themselves. Gunshots or explosions are prime examples but he said that movie theaters present a kind of hidden danger because the sound systems can produce loud, short duration, impulse noises that occur repeatedly and so quickly that the ear has no way to protect itself.

The guy was a kahuna in this town so I, pretty much, take his word.

[Marco Giustini]

Indeed, that’s exactly what I meant, Randy. Those little muscles dampening your perception and why an isolated ‘gunshot’ will appear more effective than blasting 100+ dB of sound for 40m uninterrupted.

[Carsten Kurz]

Another high-performer, 'Sound of Falling' Trailer comes with an LEQ(m) of 85. This is really not a movie where galaxies collapse. And clearly it is happening a lot more frequently in recent months. I actually had to relevel this trailer in DCP-o-matic by -6dB to get it into a range that we can cope with our limited set of Macros. We play it at 3.8 on our AP20, and it's still too loud for the type of content at least.

[Steve Guttag]

Marco, as for response from that theatre...pretty much textbook:

image.png

The subwoofers used where the QSC SB-15121 (Screen channels are SC-424/Quad-amped).

I guess there is truth in advertising, this is the graph of the subwoofer's published response:

image.png
It isn't hard to see that to tune it, one will mostly need shelving filters, like one around 40-45Hz to bring the higher frequencies down and/or one around 100Hz to bring lower frequencies up. However, it drops like a rock below 25Hz. The subwoofers (and screen channels) are mounted in a baffle wall...so, it had 2π space. You'll get a deeper response on an SB-7218 with B6 alignment. The boast about the SB-15121 not needing B6 is lost on the fact it needs the shelving filters that, effectively cost it sensitivity.

[Ryan Gallagher]

Here is a dumb question from a relatively inexperienced audio person.

I would assume drivers/cabinets/systems/room-factors have different response characteristics driven at different pressure levels. So in my head a room EQ at a particular reference level is like an idealized version anyway? If films vary greatly in overall volume, dynamic range, or due to operator fader adjustments, does this essentially leave some opportunity for that EQ to kinda be innaccuate for the situation?

Do techs typically ask what fader level range is common on features, or is everything EQ’d at reference as a practice?

Related but separately, if you were setting up a room for sensory sensitive screenings... it would ideally involve a separate EQ with slightly different goals I imagine, and not just turning the fader down to a certain level?

[Steve Guttag]

The cinema industry is almost uniquely advantaged in that the people that mix the movies and the theatres that are playing them back are referencing the same levels and response curves. So, if a theatre is tuned properly, you should get what the person that mixed the movie heard. This concept was exemplified with the THX program in the 1980s. At that point, you have the same people that are setting up the dub theatres (and actually mixing the movies) to also specify the theatre's acoustics and suitable equipment that can achieve the desired response. So, a THX theatre should sound very close to the the dubbing theatre that mixed it. The more you deviate, the less true are the results.

An argument can be made that with less ideal acoustics that one has to also have a less ideal response and level. This doesn't make it right but it might make it better. I have absolutely, on studio screenings, due to the theatre's response (which was not a purpose built movie theatre; it was a mixed use room in a museum) where I hand tuned it by ear to minimize the room's negative effects. But that is the exception, not the rule and there was no pretence that we were matching the dubbing theatre.

If you want the best presentation, acoustically, get your room right, use good equipment (speakers and amps) and tune it properly and to spec. That's it. Don't embellish. It's only when you can't do that where one has to come up with mitigation solutions where one is trying for less-bad outcomes.

[Ryan Gallagher]

The cinema industry is almost uniquely advantaged in that the people that mix the movies and the theatres that are playing them back are referencing the same levels and response curves. So, if a theatre is tuned properly, you should get what the person that mixed the movie heard. This concept was exemplified with the THX program in the 1980s. At that point, you have the same people that are setting up the dub theatres (and actually mixing the movies) to also specify the theatre's acoustics and suitable equipment that can achieve the desired response. So, a THX theatre should sound very close to the the dubbing theatre that mixed it. The more you deviate, the less true are the results.

An argument can be made that with less ideal acoustics that one has to also have a less ideal response and level. This doesn't make it right but it might make it better. I have absolutely, on studio screenings, due to the theatre's response (which was not a purpose built movie theatre; it was a mixed use room in a museum) where I hand tuned it by ear to minimize the room's negative effects. But that is the exception, not the rule and there was no pretence that we were matching the dubbing theatre.

If you want the best presentation, acoustically, get your room right, use good equipment (speakers and amps) and tune it properly and to spec. That's it. Don't embellish. It's only when you can't do that where one has to come up with mitigation solutions where one is trying for less-bad outcomes.

Thanks Steve, that is kinda my understanding of the purpose and reasoning behind the shared methods and references between studio and exhibition. I guess although some variation may be impossible to completely eliminate out in the real world... the whole point of the reference and methods is to minimize it. In my head I was just wondering what the practical implications of rooms that constantly plays features well below reference mean relative to the EQ and intent.

Obviously perhaps if the equipment and room were up to it, there might not be the perceived need to deviate very far from the reference level except with maybe a handful of acoustically abusive titles that trigger tons of patron complaints. But at least in my mind, if a room is constantly being played at 5.5 it possibly points to some other tuning or equipment issues, though we hear of plenty that default to something well below 7.0 (speaking of features, not trailer levels).