How Loud is Loud Enough (Video)

[amirm]

Landed on this video by chance by Matt Poes and Ben Goff on levels of reproduction you may need for home cinema. It is very long however, so I am going to give you a link which skips over the intro. But you may want to go to the start.

Basically, they make a case that for subs, you almost never have enough to reach reference levels. And for the rest of the spectrum, you may need playback capabilities reach some 120 dBSPL which many speakers cannot reach. I have been making a similar case for music. You have them talking about the same but for movies. And work they are doing in CEA to standardize such.

The video is not as tight and focused as I would like. I sped it up by 2X and that helps but consider it a live discussion, than a tutorial. Watch when you can dedicate the time to it:

 

[voodooless]

Basically, they make a case that for subs, you almost never have enough to reach reference levels. And for the rest of the spectrum, you may need playback capabilities reach some 120 dBSPL which many speakers cannot reach

How would that even work? At 120 dB for anything above 80Hz, the subs would need to go 130dB or more. For sure these are peak levels, but even then hearing protection would be needed.

Generally my home crowd already finds that 10 dB below AVR reference is already very loud… I very much doubt the practicality of all this, for numerous reasons.

 

[Talisman]

I don't know.... in my system in a medium-small room I have a 5.1.4 system with 4 subwoofers and front speakers with R3, I listen at about 3 meters and listening at -10db the sensation is terrifying in some scenes

 

[tineared]

I almost never watch movies near reference level do to over exaggeration of low frequencies in most movies.
I don't think the room should shake when someone slams a door
But for music...

 

[amirm]

How would that even work? At 120 dB for anything above 80Hz, the subs would need to go 130dB or more. For sure these are peak levels, but even then hearing protection would be needed.

Well, they say basically no amount of subs would get you reference level.

As to hearing damage, if you watch the video, you will see that moments of high loudness are very brief. And in bass, they just scare you more than anything. No chance of hearing damage there.

 

[EERecordist]

This topic, in my opinion, goes to the loudness wars in movie distribution. I think we may have experts on ASR in movie sound.

CEDIA is for home cinema and home automation. They want to create their own recommendations for home cinema with CEDIA/CTA-RP22 Immersive Audio Design Recommended Practice. Appendix A discusses their desired loudness levels. Personally, I think they are over specifying.

https://cedia.org/site/assets/files/6057/cedia-cta_rp22_v1_2_sept_2023.pdf

I think they may be in an update phase, so people are contributing white papers.

I was a member of SMPTE for a time with more an interest in picture standards. SMPTE is the standards group for movie sound and picture formed in 1916. With analog film picture and analog optical or magnetic sound, things are very complicated. They became involved in television, then later digital cinema. The intent is end-to-end calibration of sound and picture. I think they do a good job, but humans can override the calibration.

The governing standard is SMPTE RP 200. That specifies 85dB SPL C weighting slow as -20dBFS for LCR and 82dB for surrounds at a fader position of 7.

Then the theater would properly calibrate their fader position 7 of LCR to 85 dB SPL, and their surrounds to 82, using pink noise.

The final movie mix and mastering room LCR would be calibrated to 85 dB SPL for -20 dBFS.

The SMPTE standard goes into detail about LFE (subwoofer) calibration in the theater. Not sure CEDIA got that right.

Will music mix and mastering rooms as well as final movie mix room be capable of reproducing louder? Yes. Do audio professionals lose their hearing and as a result mix louder? Yes. You see that commonly in live sound. Musicians also lose their hearing and use louder monitors.

Can film mixers produce louder mixes with content approaching FS? And then can some theaters reduce their reference level to 78 dB as the -20 dBFS reference level using their fader because the movie mixes are too loud?

https://pub.smpte.org/doc/rp200/20021107-pub/rp200-2002.pdf

More discussion of the "loudness war" movie mixes:
(They mention the Dolby CP750 an ASR contributor discusses which is the fader in the theater)

Is The Cinema Audio Delivery Specification Still Fit For Purpose? | Audio Production: News, Tutorials & Reviews

In this article, we investigate whether the audio mixing and playback for films in cinemas needs to be overhauled, as the current calibrated audio mix and delivery system for cinema presentations has largely broken down.

www.production-expert.com

 

[mj30250]

Well, they say basically no amount of subs would get you reference level.

I haven't watched the video, but what's their logic here? Current standards define a reference level capable system as reaching 115dB peaks in the LFE channel. While this might make for a challenge in a typical domestic space where aesthetics are a primary concern, in a non-massive dedicated room this isn't all that difficult to achieve.

My space is pushing 6000cu/ft and I measured the below with "only" four commercially available, reasonably priced subs. This was taken at the MLP with no subs nearfield, the closest is roughly 11ft distant. I didn't push any further because I had reached my personal limit, but as you can see from the distortion plot the subs themselves had plenty of headroom left. This sweep caused small chunks of acoustic ceiling tile to fall to the floor and the house itself was making some disturbing noises. When RTA'ing actual movie scenes, I've measured peaks at around 133dB Z-weighted. And sure, there are systems that can go much louder than this, but I can't imagine experiencing those without hearing protection. I've seen one that had an AED mounted next to the door.

 

[voodooless]

As to hearing damage, if you watch the video, you will see that moments of high loudness are very brief. And in bass, they just scare you more than anything. No chance of hearing damage there.

That would imply that all the dynamics would need to change.

I don’t see why we couldn’t just get by with some compression to shave off om the worst peaks. 115 dB peaks seem plenty to me, and is a realistic target for a home audio system, even though it’s not exactly trivial either in the lowest registers.

And no, 130dB is not safe, not at any frequency, not in short bursts.

 

[egellings]

How would that even work? At 120 dB for anything above 80Hz, the subs would need to go 130dB or more. For sure these are peak levels, but even then hearing protection would be needed.

Generally my home crowd already finds that 10 dB below AVR reference is already very loud… I very much doubt the practicality of all this, for numerous reasons.

What about hearing damage that those playback levels could cause? I pass on that.

 

[tineared]

What about hearing damage that those playback levels could cause? I pass on that.

What?

 

[azzy_mazzy]

I haven't watched the video, but what's their logic here?

It seems to me that the calculation was done with Trinnov Waveforming, which i assume causes a loss in room gain.