How loud is loud, how to measure it? Is THX calibration bad for your health?

[audio2design]

If you read enough ASR posts you will see that lots and lots of people talk about 100+dBSPL level listening levels. Yes they have the volume control but why do they talk about high levels. Not to mention my main premise for the post is the standard that defines home theatre listening is unhealthy. Again, many posters on ASR talk about having to reach the standard levels.

That is my premise.

They can hit those peaks by I expect with rare exception that those peaks are rare. I can hit those too in my system but rarely do.

WRT movies, it varies from genrw to genre and movie to movie. A regular theater goer is not seeing Dune every time they go.

 

[sarumbear]

They can hit those peaks by I expect with rare exception that those peaks are rare. I can hit those too in my system but rarely do.

The issue is not the peaks, the average. Do please look at my charts.

 

[audio2920]

Where are these set? By who? Who chose the 79dB for instance? Where is it written?

Well, this leads on to something I was about to post but decided against it... so here goes:

Mixing levels such as 79 are sometimes, but not always, prescribed in the delivery spec for us. Netflix, for example, in their 4th bullet point:

Netflix Dolby Atmos Home Mix Deliverable Requirements v2.3

Original Language Mix for Streaming and Archive The Dolby Atmos® Original Language Home Mix must meet the following requirements: At a minimum, must be mixed in a 7.1.4 room. Dolby Certification i...

partnerhelp.netflixstudios.com

But if i had a key point to get across regarding home ent "calibration" it would be that we work to loudness spec these days, not a reference level; typically -24LKFS with peak at -2dBTP (with some variation on that theme depending who's distributing it).

The monitoring gain we use is chosen by the mixer to help them achieve that spec required by "the client" while being comfortable with the volume levels and dynamics.

So loudness spec comes first, chosen monitoring level, while often hovering around 79 if you want to give it a number to equate it to Dolby spec, is more to do with mixer preference than any kind of prescribed "reference".

You could basically ignore the whole "79dB", "85dB" thing and just set the amps at any old level, start mixing and go "oh I'm 7dB below spec, I'll turn the monitor down 7dB, trim my master fader up by 7 and crack on".

The whole "85, 79 etc" is largely irrelevant for home ent as the end result of a mix is normalised. We still use it so that (a) we have repeatability between studios and (b) we work in the right ballpark from the get-go, unlike the scenario I described in the paragraph above where you could end up in a bit of a mess with your dynamics processors.

 

[audio2920]

If you read enough ASR posts you will see that lots and lots of people talk about 100+dBSPL level listening levels.

I get your point. It's odd. I think that's why I'm always a bit preachy to anyone who will listen that they need to abandon the idea of a reference level with 105dB peaks - in the home environment.

It simply doesn't exist and it's not how this stuff is mixed.

If people wanna play stuff that loud, I don't mind, but I promise it's unlikely it was mixed to play that loud, haha.

 

[abdo123]

I get your point. It's odd. I think that's why I'm always a bit preachy to anyone who will listen that they need to abandon the idea of a reference level with 105dB peaks - in the home environment.

It simply doesn't exist and it's not how this stuff is mixed.

If people wanna play stuff that loud, I don't mind, but I promise it's unlikely it was mixed to play that loud, haha.

Is there a particular reason why the home level is lower than the cinema level?

few days ago i watched Spiderman No Way Home in an IMAX 3D cinema and an average of 75-85dB (Z-weighted) during conversations was very much the case. Music was around ~90 dB average. peaks in the 100dB to 105dB range were not uncommon for sure.

Was it loud? Yes. I still loved it though, it was incredibly immersive and i would not go and have a talk with the director about bringing the level down. It was great imo.

 

[sarumbear]

I get your point. It's odd. I think that's why I'm always a bit preachy to anyone who will listen that they need to abandon the idea of a reference level with 105dB peaks - in the home environment.

It simply doesn't exist and it's not how this stuff is mixed.

If people wanna play stuff that loud, I don't mind, but I promise it's unlikely it was mixed to play that loud, haha.

I’m afraid it does exist in the shape of the THX standard which I linked in my opening post. This is why I’m naming them.

 

[audio2920]

Is there a particular reason why the home level is lower than the cinema level?

few days ago i watched Spiderman No Way Home in an IMAX 3D cinema and an average of 75-85dB (Z-weighted) during conversations was very much the case. Music was around ~90 dB average. peaks in the 100dB to 105dB range were not uncommon for sure.

Great! As it should be. Dynamic and enjoyable for it.

Sadly, if that mix was delivered to a home environment, a lot of people would complain they had to ride the volume control, or that they couldn't hear the dialog when playing it at a lower level.

As such, home ent mixes have to have a reduced dynamic range compared to the cinema to avoid too much consumer complaint.

I’m afraid it does exist in the shape of the THX standard which I linked my opening post. This is why I’m naming them.

Yep point taken. It's just not a standard that anyone's mixing to any more. THX just don't have the market dominance to make such a standard a reality. Even the mighty Dolby can't make that so.

 

[sarumbear]

Yep point taken. It's just not a standard that anyone's mixing to any more. THX just don't have the market dominance to make such a standard a reality. Even the mighty Dolby can't make that so.

Kudos for saying it. I hope many ASR members read your post and ignore that dangerous standard.

 

[Soundmixer]

Sorry can you share with us the reference in more details?

Using a C-weighted microphone running pink noise (one speaker), what would 0 dBFS be while you’re mixing for a movie destined at home?

I mix television shows, and master and encode movies destined for the home. The typical reference volume I use for mastering is 77-79dBFS average.

I'm surprised you encode your own mixes though, I've never had to do that.

That is because the mixes are done for the most part when they get to me. We work off of the already finished theatrical mix, and I master and encode them. All of our work is done in-house for QC purposes.

 

[tvrgeek]

One of the reasons I don't go to the theaters is they are too loud. I have had to leave concerts and many a club. I like my hearing.

 

[EEE272]

Work in production of music? because this is specifically about listening systems not random work related noise. That was kind of my point.

No, as I explained above. Afaik, there are no long term studies on the effect of music on your hearing. So the standards that we now specify for music, which you also quoted, are based on data of workers in an industrial context.

 

[EEE272]

I mix television shows, and master and encode movies destined for the home. The typical reference volume I use for mastering is 77-79dBFS average.

That is because the mixes are done for the most part when they get to me. We work off of the already finished theatrical mix, and I master and encode them. All of our work is done in-house for QC purposes.

Thanks a lot for all the insights! That is really awesome information and the long post is really clear. I really appreciate all the effort that went into it.

BTW. I tested the ypao volume function (loudness compensation) a lot today to figure out, how it works. It seems to be made for a reference of 70dB - it kicks in below -15dB.
Based on what you wrote, it could be that they were aware of home content often being mixed at lower levels.

 

[tvrgeek]

Yes, if you read the OSHA guidelines it talks abut levels for time. Not dynamics. However, just about every musician I know over 50 is severely hearing damaged.

So those of you out there who run mixing studios, PLEASE be careful of that 3K band. I will give up a little detail not to hear nails on a chalkboard, AKA "digital glare"

 

[Descartes]

Occupational Noise Exposure - Overview | Occupational Safety and Health Administration

www.osha.gov

Here you are!

I also agree, all movie theaters play movies way too loud, not enjoyable at all! I suspect they do this to cover all the coughing, sneezing, chewing and talking from all the viewers in the room.

No thanks! I have not been to a multiplex in ten years would rather buy the Blu-ray or 4K Blu-ray and enjoy it at home! Better sound and picture without all the noise distractions, nasty smells of hotdogs, popcorn, obnoxious patrons, uncomfortable seats and sticky floors!

 

[EEE272]

Netflix Dolby Atmos Home Mix Deliverable Requirements v2.3

Original Language Mix for Streaming and Archive The Dolby Atmos® Original Language Home Mix must meet the following requirements: At a minimum, must be mixed in a 7.1.4 room. Dolby Certification i...

partnerhelp.netflixstudios.com

But if i had a key point to get across regarding home ent "calibration" it would be that we work to loudness spec these days, not a reference level; typically -24LKFS with peak at -2dBTP (with some variation on that theme depending who's distributing it).

I am still curious about how the normalization affects your creation.

Given that it targets -27 LKFS, which is around 78dB K-weighted, if I understood correctly, we kind of have at least a reference level of the content.

Is there a lot of variance in the end between your original loudness when mixing and the final version after normalization?
When they normalize for this level do they apply some loudness compensation?
Or is that not relevant because they did specify that mixing should take place at 79 to 82, so the loudness difference is minimal?

Thanks in advance!

 

[sarumbear]

Given that it targets -24 LKFS, which is around 81dB K-weighted, if I understood correctly, we kind of have at least a reference level of the content.

There is no fix correlation between LKFS (which is another name to LUFS) and dBFS (which I assumed you meant). It all depends on the material being measured.

 

[Soundmixer]

Is there a particular reason why the home level is lower than the cinema level?

Yes, there is. A commercial theater is far larger than the typical home theater. Therefore the speakers and every parameter associated with reproducing soundtracks in a larger space must be scaled down to a smaller space. This is why you have "Mixed (which should be mastered) For Hometheater" soundtracks.

 

[EEE272]

There is no fix correlation between LKFS (which is another name to LUFS) and dBFS (which I assumed you meant). It all depends on the material being measured.

Why is that?
Is Lufs not defined as the average k- weighted result?
Then it would mean that if I listen to it on my amplifier adjusted for 105dB at full scale, I would get back kweight(105)-27 LUFS, so 78 dB k weighted on average, no?

Sorry that I am so confused by all of this.

 

[sarumbear]

Why is that?
Is Lufs not defined as the average k- weighted result?
Then it would mean that if I listen to it on my amplifier adjusted for 105dB at full scale, I would get back kweight(105)-27 LUFS, so 78 dB k weighted on average, no?

Sorry that I am so confused by all of this.

LUFS measures the loudness over time, it is like RMS but instead of integrating sine wave it’s integrating music. It has nothing to do with weighting.

Here is a good explanation.

https://www.sweetwater.com/insync/what-is-lufs-and-why-should-i-care/

 

[EEE272]

LUFS measures the loudness over time, it is like RMS but instead of integrating sine wave it’s integrating music. It has nothing to do with weighting.

Here is a good explanation.

https://www.sweetwater.com/insync/what-is-lufs-and-why-should-i-care/

Thanks for the link, it had an interesting passage in the end, where he points out that if different providers use different normalization, he listens to the new normalized version at the suitable loudness and then decides if a new mix is needed. This answers my question above.

Regarding the k weighting.
Wikipedia defines LUFS or LKFS as k weighted average with respect to dBFS.
K weighting seems somewhat close to the human hearing. Only dbFS is indeed not linked to any analog loudness, which then would mean that the Netflix LUFS specification means nothing with respect to the actual sound. But I think I got it now because this part is handled by the Netflix spec saying that the mixer should mix at 79 to 82 dB, hereby anchoring an analog level. Pretty neat actually.