Are you REALLY listening at Reference Volume??? Maybe Not...

[Todd Anderson]

On a recent @Bright Side HT podcast, show guest Paul Hurt, a sound technician that mixes both music and TV material, joined host DJ Briggs with an interesting spin on reference volume levels.

Just a bit of background, but the reference levels we set our processors and AVRs to are typically either 75dB or 85dB, depending on whether you're following THX or Dolby standards. Those numbers are derived from being either -30dB or -20dB from a max SPL of 105dB, which gives sound engineers a wide amount of dynamic range to master everything from wispy wind and dialog to window-rattling explosions.

The idea is to calibrate your system so that your speakers are channel leveled to either 75 or 85dB at the primary listening positing in a room. Thus, when you turn your volume knob to "0" on a relative volume scale, you're operating at reference level, meaning that you're hearing the content - from the whisper quiet to the loud - at a loudness level that a mixer intends you to experience.

Short end of the story is that Paul says reserach in psychoacoustics in small rooms says that a loud sound (say, 75dB) sounds louder in a small room than a large room (like a theater). Thus, mixers have found that reference minus 6dB is the best level for reference mixing. Thus, if you want a reference experience, you should be gunning for -6dB on your receiver or processor.

DJ can chime in here. Hopefully we can Paul to join the thread and talk shop about this.

In the mean time, curious to hear thoughts!

 

[Bright Side HT]

On a recent @Bright Side HT podcast, show guest Paul Hurt, a sound technician that mixes both music and TV material, joined host DJ Briggs with an interesting spin on reference volume levels.

Just a bit of background, but the reference levels we set our processors and AVRs to are typically either 75dB or 85dB, depending on whether you're following THX or Dolby standards. Those numbers are derived from being either -30dB or -20dB from a max SPL of 105dB, which gives sound engineers a wide amount of dynamic range to master everything from wispy wind and dialog to window-rattling explosions.

The idea is to calibrate your system so that your speakers are channel leveled to either 75 or 85dB at the primary listening positing in a room. Thus, when you turn your volume knob to "0" on a relative volume scale, you're operating at reference level, meaning that you're hearing the content - from the whisper quiet to the loud - at a loudness level that a mixer intends you to experience.

Short end of the story is that Paul says reserach in psychoacoustics in small rooms says that a loud sound (say, 75dB) sounds louder in a small room than a large room (like a theater). Thus, mixers have found that reference minus 6dB is the best level for reference mixing. Thus, if you want a reference experience, you should be gunning for -6dB on your receiver or processor.

DJ can chime in here. Hopefully we can Paul to join the thread and talk shop about this.

In the mean time, curious to hear thoughts!

Thanks for starting this Todd. Reference level has always been a hot button topic for Home Theater Enthusiasts and what Paul and I set out to do was to get some answers on 1. how the industry gets there and 2. how we get there in our Homes. What Paul uncovered was a bunch of variables that pretty much answer the age long question as to why different discs sound so different. And he also found out there have been blind test studies done to see how to best duplicate the in Cinema Experience in our homes. If you haven’t already listened to Paul and I talk about this on the podcast definitely listen and then bring your questions or comments here. This is a fascinating development that, in my opinion, gives us some solid foundation to build on when answering “what is reference level?”.

 

[Paul Hurt]

Hey, hi folks. Here to help

Hope you can find time to have a listen to the podcast - it’s another long one! - but I’m happy to try and explain anything that isn’t making sense. I realise it’s a confusing subject - I tried my best in the interview to be as clear as I could, without getting super-technical.

It’s also a bit of an ongoing investigation, so I hope you’ll excuse me if I don’t have ALL the answers. Mixing levels and audio system calibration are topics that continue to be debated in the movie industry itself, and standards and practices never completely settle down. Plus there’s always someone that wants to do things differently.

There are areas I’m still looking into with the help of a couple of big-time movie production insiders who happen to also have listened to the podcast (!! and thankfully seem to be backing me up). Some of the stories they’ve told me would make you throw your popcorn across the room.

But if, when you set your home theater to “reference level” you’ve felt a movie has sometimes been either a) way louder than could possibly be correct, or b) different titles have been all over the place in terms of volume, I think we can help. Rest assured that you are not imagining it.

 

[Paul Hurt]

But TLDR: if you’ve calibrated your home theater for audio levels (either manually or using one of the auto-calibration systems) so that 0dB on your volume control is “reference”… try using -6dB instead as your starting point when cueing up a movie. You may even need to turn it down a little from there.

YMMV.

 

[JStewart]

Hey guys, thanks for this! Fascinating and enlightening discussion in the podcast.

I didn’t see a link in this thread to the podcast being discussed

https://static1.squarespace.com/static/5f446647cf8e9a235aef9f66/t/64a3723644d56f5c35318f9c/1688433259445/HT+294+Paul+Hurt+Reference+Level.mp3/original/HT+294+Paul+Hurt+Reference+Level.mp3

One possible clarification, I don’t believe Dirac calibrates volume on a processor as Audyssey does.

And a curiosity question… does Kaleidescape use the theatrical soundtracks?

 

[Todd Anderson]

Hey guys, thanks for this! Fascinating and enlightening discussion in the podcast.

I didn’t see a link in this thread to the podcast being discussed

https://static1.squarespace.com/static/5f446647cf8e9a235aef9f66/t/64a3723644d56f5c35318f9c/1688433259445/HT+294+Paul+Hurt+Reference+Level.mp3/original/HT+294+Paul+Hurt+Reference+Level.mp3

One possible clarification, I don’t believe Dirac calibrates volume on a processor as Audyssey does.

And a curiosity question… does Kaleidescape use the theatrical soundtracks?

Kscape soundtracks aren’t the theatrical version… they won’t confirm or deny this, but I think they’re the same exact lossless file that you’ll find on a disc. The picture is where there might be less compression of the overall file. I could be wrong about that tho - if the audio files aren’t the same, they’re pretty close

 

[Todd Anderson]

Hey, hi folks. Here to help

Hope you can find time to have a listen to the podcast - it’s another long one! - but I’m happy to try and explain anything that isn’t making sense. I realise it’s a confusing subject - I tried my best in the interview to be as clear as I could, without getting super-technical.

It’s also a bit of an ongoing investigation, so I hope you’ll excuse me if I don’t have ALL the answers. Mixing levels and audio system calibration are topics that continue to be debated in the movie industry itself, and standards and practices never completely settle down. Plus there’s always someone that wants to do things differently.

There are areas I’m still looking into with the help of a couple of big-time movie production insiders who happen to also have listened to the podcast (!! and thankfully seem to be backing me up). Some of the stories they’ve told me would make you throw your popcorn across the room.

But if, when you set your home theater to “reference level” you’ve felt a movie has sometimes been either a) way louder than could possibly be correct, or b) different titles have been all over the place in terms of volume, I think we can help. Rest assured that you are not imagining it.

Very interesting topic, Paul. Thanks for jumping in! Our community can really benefit from your contributions!

Btw, in the podcast, you and DJ had touched on bass being neutered by certain studios. I had a conversation with someone that has direct access to someone at one of the big names in audio… they confirmed that bass is being clipped, with the reason being that most content is consumed on devices and TVs. The weird thing is that the audio engineers on the studio side aren’t (or, at the time, weren’t) the ones doing it… in fact they were surprised to hear of complaints. It was being done after the fact… after the finalized audio files were handed off.

 

[Bright Side HT]

Hey guys, thanks for this! Fascinating and enlightening discussion in the podcast.

I didn’t see a link in this thread to the podcast being discussed

https://static1.squarespace.com/static/5f446647cf8e9a235aef9f66/t/64a3723644d56f5c35318f9c/1688433259445/HT+294+Paul+Hurt+Reference+Level.mp3/original/HT+294+Paul+Hurt+Reference+Level.mp3

One possible clarification, I don’t believe Dirac calibrates volume on a processor as Audyssey does.

And a curiosity question… does Kaleidescape use the theatrical soundtracks?

Here’s a link that should cover people finding any of our podcasts or YouTube videos.

linktr.ee/BrightSideHT

And this one takes you directly to the Apple Podcasts version of Paul’s latest episode that started this.

 

[Paul Hurt]

Hi Todd. Yes, the mixes we get on home media are not quite the same mixes that go out to theatres. They "do some work" to them for the Home Entertainment version that we get. How much work gets done seems to depend on the preferences of the studio/label, the title in question, and how much "work" they think that title needs.

They have definitely been known to tweak the bass in places - and I don't imagine they ever turn it up! So you can bet it's either being turned down, or the lowest frequency bass is filtered out. There's a scene in The Matrix which has never sounded right to me at home because a giant LFE thump that was definitely there in the theatre seems to have completely gone missing.

This is actually an odd decision when you think about how bass is handled in playback systems. If you don't have a subwoofer the LFE track gets thrown away for a start. And active subwoofers can easily be designed to cope with whatever gets thrown at them - by the use of limiters and high-pass filters.

There are also some discs I can think of where it's obvious that the peak dynamic moments have been limited or volume-automated to be less dramatic. (Avengers: Age Of Ultron being the most egregious example)

One source even told me that the entire soundtrack gets blanket compression across it for Blu-ray, but I can't confirm that, and there are plenty of discs that don't sound that way to me. Though good and/or subtle compression is hard to detect, so I'd never want to swear to it.

But it ain't all doom and gloom. I think most disc soundtracks sound good, and all but one or two of the ones I measured for the podcast had plenty of dynamic range. Some soundtracks I'm sure get next to nothing done to them, outside of maybe some eq tweaks to tailor them to suit our small point-source systems, instead of big theatrical X-curve type systems

(I have one Blu-ray where I'm pretty certain it is the original theatrical mix just thrown onto the disc, because it's crazy bright).

I would love it if more studios were as concerned with preserving the original intent of the soundtrack as they are about rescanning the camera negative and restoring it to match the director's intent. It could be a good marketing angle - "Featuring the original full-dynamic-range theatrical surround mix in uncompressed Dolby Atmos." Yes please.

But if my experience of the music and TV industry is anything to go by, I'm betting a lot of production decisions about the final sound are being made by people without a true technical background. I'm sorry to say that many film and TV directors/producers only really concern themselves with the visuals, and look at sound as an afterthought to be left to the technical folk. Half of them wouldn't know one end of a microphone from another.

 

[Paul Hurt]

Anyone interested in the current industry thinking on calibration, reference level, and mix levels should have a read of the ATSC document ATSC A/85:2013:

"Techniques for establishing and maintaining audio loudness for digital television"

[Sorry, I'm too new here to post the actual link, but you'll find it if you Google it]

In particular check out pages 35 and 36.

Much of the document relates to Dolby AC-3 because that's the audio format that was mandated for digital television when the US changed over to digital broadcast HDTV. But it's still relevant today when mixing for "Home Entertainment" use e.g Blu-ray disc, streaming, etc.

 

[VJM]

@Bright Side HT can you give Paul access to the Greenroom?

@Paul Hurt, FYI since you don't currently have access, here's a chart I referenced in the thread I mentioned in my tweet...

 

[VJM]

Anyone interested in the current industry thinking on calibration, reference level, and mix levels should have a read of the ATSC document ATSC A/85:2013:

"Techniques for establishing and maintaining audio loudness for digital television"

[Sorry, I'm too new here to post the actual link, but you'll find it if you Google it]

In particular check out pages 35 and 36.

Much of the document relates to Dolby AC-3 because that's the audio format that was mandated for digital television when the US changed over to digital broadcast HDTV. But it's still relevant today when mixing for "Home Entertainment" use e.g Blu-ray disc, streaming, etc.

Thanks Paul, here's the link https://www.atsc.org/atsc-documents...aining-audio-loudness-for-digital-television/

 

[VJM]

But TLDR: if you’ve calibrated your home theater for audio levels (either manually or using one of the auto-calibration systems) so that 0dB on your volume control is “reference”… try using -6dB instead as your starting point when cueing up a movie. You may even need to turn it down a little from there.

YMMV.

If you really want -6 to show as 0 on your volume, I know my Denon and the Marantz have an option to set the level offset according to the input (Source Level), so it's possible to set that down to -6 so going to 0 will actually be -6 for that input.

https://manuals.denon.com/AVRX3700H/NA/EN/GFNFSYyvbqibdw.php

 

[VJM]

I would love it if more studios were as concerned with preserving the original intent of the soundtrack as they are about rescanning the camera negative and restoring it to match the director's intent. It could be a good marketing angle - "Featuring the original full-dynamic-range theatrical surround mix in uncompressed Dolby Atmos." Yes please.

Speaking of this, I've been watching all of the Mission Impossible moves getting ready for number 7 and they all have excellent sound, very dynamic and clean.

Your quote about the full dynamic-range theatrical surround mix, I have seen that before but only on the Christopher Nolan 4k releases and we know how these sound

 

[Paul Hurt]

Thanks for all that VJM, super useful.

To get my Denon calibrated for a 79dB reference level - not using Audyssey - I set my master volume to +6dB, then calibrated each speaker to 75dBC as you'd normally do. For Audyssey fans, that input offset level function sounds like a handy workaround.

Either way, that should give you 69dB from the test tones (or 79dB in professional dubbing room money) when you have your volume at 0dB.

Moving on from my rough and ready handheld SPL meter measurements, I've started doing investigations with REW and a calibrated UMIK-1. Has been super-interesting. For a start it's made it easier to calibrate my speaker levels with more precision, and even that was quite revealing. I can recommend using the tones on Spears & Munsil over the built-in pink noise tones - I find the disc easier to handle, and the on-disc pink noise tones have been correctly band-limited unlike the test tone from a Denon 4400.

As part of this research, I've also started taking more accurate measurements of dialog level and peak "action" level from various discs, because if my assessment of dialog level is a couple of dB off - which is often be the case when you try to do this with an ordinary SPL meter - all my other measurements relative to that won't be quite as valid. I'm now able to work out a surprisingly accurate volume offset for each movie which puts the dialog at a comfortable level.

I'm finding if I set my master volume so that normal dialog averages 71dBC (I know this will never be an exact science, but I'm getting good at hitting that target) the rest of the movie falls nicely into place. It's interesting how the whole system feels more to me like being at a good movie theatre when the dialog is no longer shouting at me... and I'm not continually playing with the volume.

Calibrating and then logging the SPL level of action scenes with REW also seems to reveal whether these scenes have had their peaks limited. I can comment more on that when I have more data.

 

[Paul Hurt]

Ha, just realised, you also got on that ATSC document I was referring to, back in your greenroom discussion.

Good work. See, I knew i wasn't the first person to start figuring this out.

I'd also mention that the "Room Calibration For Film And TV Post" thread on the Avid Post-Production discussion forum has been running for TWENTY YEARS this year. One thread, started in 2003, and still just about going! Tho over the time that thread has been running, the thinking and recommendations on calibration have shifted a few times. Even now there's much talk about using dBA instead of dBC for speaker level calibration, although that is mostly recommended for X-Curve type theatrical systems.

 

[Lesmor]

interesting subject
I was under the impression 0 on a AVR = 85dbfs but that is too loud for most people so that's why you calibrate to 75db using Audyssey
also why 0 on the Spears and Munsil disc = 75db

what I have found is that there is no consistency between calibration disc level checks
you can use the Spears and Munsil swap to a Dolby atmos demo disc and use the level check on that and get a different result
you can use a Trinnov's output pink noise get that balanced then try the Spatial Audio calibration toolkit and they don't match

as to a comfortable listening volume, I think this depends on room distortion (different from speaker distortion) if you have a treated room you can listen at a higher setting on the main volume control

I believe when mixing Atmos studios calibrate all levels equally
for other content the surrounds are calibrated at -3db
just my 2cents

 

[Paul Hurt]

The 75dB “home” calibration standard comes about because the test tones used on home systems are 10dB quieter than those used in pro environments. So -20dBFS test tones calibrated for 85dBC and -30dBFS test tones calibrated for 75dBC end up giving you the same level in the room when you play content.

If pushed for a reason, my guess would be that high SPLs are more tolerable in treated rooms than untreated rooms because most of the treated rooms you see in home theaters have a lot of high and mid-frequency absorption, and that tends to change the spectrum of the audio that reaches your ears. It reduces frequencies that we typically interpret as “harsh” eg those over around 1kHz, so we will put up with a few more dB SPL. I’ve noticed the same thing happens if you use Audyssey at its default settings - Audyssey subtly rolls off high frequencies which makes soundtracks seem less harsh (AND potentially less intelligible). So they end up feeling not quite as loud, even though they measure the sane SPL.

FWIW, recording studios try to limit how much HF absorption they are using, specifically to avoid rooms sounding too dull and “boxy”. The big acoustical problems are low frequency ones anyway, so that’s where most of the effort is focused.

 

[VJM]

@Paul Hurt how deep in the rabbit hole are you on this? Have you dug into the Dolby Dialnorm confusion?

 

[VJM]

Here's some more good info

Are TV Mixes Getting Too Big For The Domestic Living Room? | Pro Tools - The leading website for Pro Tools users

Are some of our high-end TV dramas and high budget entertainment shows being mixed in suites designed for theatrical releases and is this why we are finding as a family that we are having to resort to sub titles more and more to be able to follow the plot?

www.production-expert.com

I also found this somewhere:

Size Matters Early on, both Dolby and THX noticed that movies made for theatre at the 85dB reference level sounded way too loud and played with incorrect tonal balance when played back in smaller mastering rooms. This is why it’s a good idea for movies mastered for the theatre to have a final pass on a proper sound stage the size of a theatre and not in a small mastering room - so that final adjustments can be made to the soundtrack. To have the soundtrack play back with the correct loudness and tonal balance in a smaller mastering - or home theatre in our case, the soundtrack needs to be attenuated by 4dBs (85dB - 4dB = 81dB reference). Dolby’s solution was Dialogue Normalisation (DialNorm): with the above in mind, Dolby mandated DialNorm with a default offset of -4 to be used on all Dolby movie soundtrack bitstreams mastered for the home environment. This allowed the soundtrack to play with the correct tonal balance and “loudness” while loudness management and dynamic range compression algorithms could be applied correctly according to ISO226.

 

[Paul Hurt]

@Paul Hurt how deep in the rabbit hole are you on this? Have you dug into the Dolby Dialnorm confusion?

Oh I *deliberately* avoided talking about dialNorm on the podcast!!! It’s confusing enough for sound engineers - it’d probably make most home theater people’s heads explode.

dialNorm should have been a great solution - was designed to make it possible to take mixes done at different levels, stick them on a DVD, and have them play back at home at a consistent level. But errors in setting and using dialNorm only make the situation worse. And as I say, there’s a ton of pros that don’t understand what dialNorm does.

 

[Paul Hurt]

But as I mentioned before, there’s a single thread over at the Avid Post-production Community forum that’s * twenty years long * where professional sound engineers go back and forth about calibration, levels, X-curve, SPLs etc. People imagine that sound engineers working in the film and TV fields all understand this stuff already. Not necessarily… obviously until someone teaches them this stuff they won’t really know about it. And with a lot of independent projects being edited and mixed at film-makers’ homes, there’s a lot of relatively inexperienced people grappling with it all, and mistakes get made. Thankfully that thread exists specifically to answer these sort of questions. Yet still it seems discs are being authored with audio levels that are a bit all over the place.

I also think when final mixes are being done for film, there is a slight trend of using plugins everywhere in an effort to keep some control over the mix and make elements stand out in increasingly busy mixes. It’s so easy now to put a compressor and/or limiter on everything if you want… but this doesn’t make for exciting mixes, it tends to make dense near-unlistenable mixes.

You couldn’t do that “back in the old days” because every compressor was a separate piece of hardware, so you only had so many to work with during the mix. Now you can put three software compressors on each of 100 different tracks of your mix, if you really think you need to.

There are a lot of interconnected factors at play, and I expect these are contributing to the loud movies we are getting nowadays, and movies that are mixed over-loud are not helping the industry down the line.

 

[VJM]

Oh I *deliberately* avoided talking about dialNorm on the podcast!!! It’s confusing enough for sound engineers - it’d probably make most home theater people’s heads explode.

dialNorm should have been a great solution - was designed to make it possible to take mixes done at different levels, stick them on a DVD, and have them play back at home at a consistent level. But errors in setting and using dialNorm only make the situation worse. And as I say, there’s a ton of pros that don’t understand what dialNorm does.

Yeah that's a shame that the a lot of pros don't understand DialNorm, not to mention sometimes it's more then -4 offset or not set at all.
Good thing the newer Denon receivers can ignore DialNorm now so it makes it much easier to deal with.

 

[JStewart]

Here's some more good info

Are TV Mixes Getting Too Big For The Domestic Living Room? | Pro Tools - The leading website for Pro Tools users

Are some of our high-end TV dramas and high budget entertainment shows being mixed in suites designed for theatrical releases and is this why we are finding as a family that we are having to resort to sub titles more and more to be able to follow the plot?

www.production-expert.com

I also found this somewhere:

Interesting article.

I’ve done some informal experimenting the last couple of days armed with some new information from this thread.

My room is small. Approximately 1500 cubic ft. Following the idea of @Paul Hurt (thank you!), I’ve found setting the movie dialog to 68/69dB (C weight, slow) gives a good result. Speaking toward the umik from about a foot away yields the same SPL. I can watch the movie through with the loud parts seeming realistically loud and without feeling the need to tinker with the volume control at any point. Dialog at any level stays intelligible. But with the volume set this way I only get 75dB SPL using -20dBFS pink noise to a single speaker. I found this surprising because I thought it would be louder. I must be misunderstanding something.

I also calibrated relative loudness using band limited pink noise. 500Hz to 2kHz. The coherence of the sound bubble seemed better to me although the trim changes were minor, the largest being the side surrounds at +1.5dB, so in this case my observation appears to at least pass the inter-occular.

 

[Paul Hurt]

Nice work! Im still experimenting, and everyone’s mileage is bound to vary… but Im also finding that if I aim to set my system volume so that the average Dialog level sits around 71dBC I’m pretty happy, and just like you, everything else seems to just fall nicely into place when I do that.

I’m measuring levels using REWs SPL logging feature now, which makes it easier to establish what the average level might be, because Im looking at a plot of SPL vs time. Tho because of the long release time of the slow response setting, there’s still a trick to interpreting the graph.

So (hope you can follow this ), first, I’m calibrated to -20dB pink = 79 dBC when my volume is at 0dB ie reference. I’m then measuring Dialog on Blu-ray titles and typically finding that for many movies my volume control has to be around -6 or so to give me 71dBC Dialog. So, if I was to leave the volume there and then play -20dB pink again, it would measure 73dBC. So that’s pretty close to what you’re getting. But of course it will vary a bit depending on the movie you’re watching. From measuring various discs I’ve found as much as a 10dB difference in dialog levels between some titles (eg the old Empire Strikes Back blu-Ray is the loudest disc I’ve found so far, Contact blu-ray the quietest). So I’ve worked out, if I was watching that version of Empire, I would have to set the volume to -15 to get my desired Dialog level, and then the test tones would measure 64dBC !!

But It’s all good . If you’re happy with the way your system sounds then whatever level you’re at is the right level . Im finding it helps a lot to be on top of this tho, arent you? I like starting a movie knowing I’m less likely to have to keep tweaking the volume throughout the film. Means I can just settle back and watch it.