This article evolved from an email to the AIR listserv back in March. Questions around levels for podcasts and radio kept coming up, so I sat down one night in the midst of preparing for a move from Minneapolis to Washington, DC, to hammer something out to address them. I ended up with a quick-and-dirty explainer, along with a couple of step-by-step examples for various platforms. What follows is certainly not an exhaustive explanation, but instead an attempt to give those who are curious a little more information.
Radio and podcasts need two different loudness targets: -24 LUFS for radio and approximately -18 LUFS for podcasts. It’s best to do all of your production at the lower “radio” level, even if your final product is to be at the higher “podcast” level. To get from -24 LUFS to -18 LUFS, use the steps outlined at the end of this document or use software specifically made for the purpose.
First, Some Context
The loudness standards for public radio distribution are welcome in that they allow us to define a single target for moving content around the various public radio systems, regardless of its production style. My previous article at Transom, The Audio Producer’s Guide to Loudness, addresses how to achieve the -24 LUFS target used in radio production.
The radio standard doesn’t address a loudness target for podcasts… and it’s not likely to. Those of us involved in making that standard were primarily concerned with passing content amongst the distribution points in the public radio system.
Podcasts are addressed in a recommendation by the Audio Engineering Society. It’s long and technical (I know because I helped write it!) so I’ll spare you the details: it recommends that podcasts target somewhere between -20 LUFS and -16 LUFS depending on the style of content. Most of you reading this probably produce talk content, and that means -18 LUFS, the very middle of the recommended range, will suit your needs nicely. (If you are already producing podcast content at -16 LUFS, a number that was often suggested until the AES recommendation was born, don’t sweat it, you can keep doing what you are doing — or move down a little to -18 LUFS.)
So now we’ve got two loudness targets depending on your destination:
- Traditional public radio: -24 LUFS
- Podcasts: -18 LUFS
YES, YES BUT WHY THE HECK ARE THERE TWO STANDARDS?
The lower -24 LUFS radio spec allows for a wide dynamic range. That means audio producers can create programming with soft, low-level peaks and louder, hotter-level peaks and everything in between (within good production practices) as long as the overall average loudness is -24 LUFS. Talk radio might not take full advantage of this wide dynamic range, but music programming certainly does, so the folks who made the radio standard had to keep a wide variety of content in mind when they created it. This dynamic range is what allows one producer to have a very compressed and punchy sound while another has a more natural and open sound. As long as they target the same loudness value, in general the two programs will sound equally loud over time.
Podcasts (and podcast-like content), on the other hand, are frequently enjoyed on mobile devices. Unfortunately phones and tablets don’t have the highest-quality audio playback capabilities. They do just fine with louder content like pop music but they have a hard time dealing with lower level content like that produced at -24 LUFS. You can certainly turn up the listening level on the phone, but it may struggle to raise the -24 LUFS content to a consistently comfortable listening volume. If you were listening to your stereo, you’d turn the volume knob up to a comfortable listening level and you’d probably still have a looooong way to go before the knob hit “max” volume. In fact, if you turned the stereo up to max, your cat would freak out, your landlord would evict you, and you’d probably suffer from some severe hearing loss (you poor sap). Your phone, however, just can’t compete with this due to the limitations of its electronics. It doesn’t have the capability to significantly boost lower level audio like your stereo does. (Frankly, to protect your hearing, you don’t want it to, otherwise you could accidentally hurt yourself when listening on headphones.)
Compounding this problem: when folks listen to podcasts on a mobile device, they are likely on-the-go. Commuting via metro (ahem… subway… I’m a DC boy at heart it seems), bus, walking, whatever. Or they are listening while doing the dishes or driving in the car. All of these scenarios will have loud background noise that competes with the audio.
Louder listening environments, combined with a mobile device’s inability to pump up the volume, means we need a higher loudness target for podcasts.
Let’s take a Nick Quah-style GIF break, shall we?
The possibility for a wider dynamic range in the radio spec works well for radio because every station includes processing before the signal is broadcast over the air. Processing like compressors, limiters, companders — equipment that squashes down some of the peaks, brings up the lower levels, and reduces the dynamic range. This processing helps the signal survive over-the-air transmission, helps it be more audible in environments like the car or the kitchen, and shapes the sound of the station. Each station wants to tailor its sound based on its own tastes and content, and they do that by processing their signal differently than the other stations in their market. One station may prefer a more natural sound (often the choice most public radio stations make), while another station may prefer a more compressed and aggressive sound (typical of Top 40 or commercial talk radio).
The public radio loudness standard ensures that each station will receive every program from the distribution system at a consistent loudness. That consistency allows them to fine-tune their processing to their liking and create the sound they want.
If the processors are squashing the dynamic range anyway, why don’t we just use the -18 LUFS podcast target for radio production? It would be easier to have one number for everything.
Well, a higher loudness target means lower dynamic range and that effectively steals the dynamic range from those producers who want it. There are certainly producers out there (like yours truly) who prefer to have the option of a wider dynamic range when they need it. Music productions especially want that wider dynamic range, but so do some more traditional talk programs like many of the daily news magazines you know and love.
Another reason not to produce everything at -18 LUFS is a logistical one. The higher peaks associated with a higher loudness target make it really difficult to produce much of anything without some kind of processing… especially when you are producing live radio! Case in point: if you sat down with your portable recorder and shotgun mic right now and tried to record your voice at the equivalent of -18 LUFS, you’d distort the recorder. To prevent the distortion you’d need compression and limiting in line before the signal reaches the recorder, and that’s before you’ve even gotten a chance to listen to your audio. You’d have to process the sound before it was recorded. That’s not best practice and it would be expensive… no good.
To sum up…
- Traditional public radio: -24 LUFS
- Allows for a wider dynamic range for those who want it.
- Is at a level that is low enough for everyday production without needing compressors and limiters.
- Ensures stations receive content that is consistent from program to program.
- Podcasts: -18 LUFS
- Overcomes the limitations of mobile devices.
- Overcomes the limitations of the environments where our listeners find themselves.
- Requires reducing dynamic range.
Getting From -24 LUFS for Radio to -18 LUFS for Podcast
You’ve read The Audio Producer’s Guide to Loudness so you have the tools and know-how to produce content at -24 LUFS (if you need more help, let me know.). That’s great, because as stated before it’s much easier to record and mix audio at -24 LUFS. I recommend doing all of your production (recording, editing, and mixing) at -24 LUFS. Even if your content will never air on the radio, produce it at -24 LUFS first. Once everything is sounding amazing at -24 LUFS and you feel like the mix is done you can convert it to the -18 LUFS podcast target.
(Yes, there will be opinions raised against this idea. It’s an extra step (read: some extra mouse clicks). Also noise floor concerns are sometimes cited… but gear these days is of such quality that noise floor is not a major concern. And, frankly, distorting your recording device — which is what would happen if you tried to record at a super high loudness like -18 LUFS — is way worse than any potential noise floor problem.)
To convert from the lower -24 LUFS mix to the -18 LUFS podcast target we are going to reduce the dynamic range — reduce the peaks — so that we create room to raise the overall loudness of the file. If we tried to raise the loudness of the file without reducing the peaks, we’d end up with distortion, as many of the peaks would push to 0 dBFS. That’s bad. By managing the peaks first, we give ourselves more headroom — the space between the highest peak in the file and 0 dBFS. We’ll first use a limiter (either manually or via an automated workflow) to reduce the peaks and increase the headroom, then we’ll raise the gain of the entire file (again, either manually or via an automated workflow).
- Mix to -24 LUFS average.
- Limit to manage peaks.
- Increase gain.
(This method, by the way, was introduced by Thomas Lund in his 2013 paper titled Audio for Mobile TV, iPad, and iPod.)
There are a few ways to do this, but I’ll outline some straightforward methods here using commonly available tools.
- Bounce or export your -24 LUFS mix to a file. Be sure to label it appropriately so you don’t get confused later, because we are going to end up with two files, one at -24 LUFS and the other at -18 LUFS. I typically put “neg24” in the filename of this file.
- Import your file to a new session or track.
- Open the AudioSuite plugin called “Maxim” (see above) (Audiosuite -> Dynamics -> Maxim). Maxim is not a great limiter, it’s a free one that comes with Pro Tools. If you have access to a nicer limiter, such as the Waves L1, or similar, please use it instead! You can probably use the same settings as we indicate in the graphic here, but you may need to experiment a little with the specific plug-in you’re using.
- Adjust the parameters to look like so
- Highlight the entire file.
- Click “Render”.
- Assuming you started with a -24 LUFS mix, you now have an approximately -18 LUFS file!
(A quick aside — Hindenburg also includes a cool Auto Level preset called US Public Radio to help you make the -24 LUFS mix.)
Adobe Audition has a nice feature called “Match Volume” that will do the conversion to -18 LUFS. It’s not perfect — it doesn’t let you fine-tune the peaks, but it does a decent job.
- Open the Match Volume window.
- Drag your file from the File window to the Match Volume window.
- Click on Match Volume Settings. In the “Match To” field choose “ITU-R BS.1770-2 Loudness”
- Select the “Use Limiter” box and make sure the other settings are set like this:
- Click Run!
(Insider info — I’m told that a future version of Audition will likely include a preset for US Public Radio to help get mixes normalized to -24 LUFS.)
Voilà. You bumped your -24 LUFS radio mix to -18 LUFS for your podcast… AND you didn’t have to change any of your normal mixing techniques to get there.
[Editor’s Note: Added May 27, 2016]
A quick update. It turns out the wonderful folks at Adobe have updated Audition CC since I wrote this article. They’ve changed the name of the tool from “Match Volume” to “Match Loudness” AND added a nice adjustable True Peak limiter. It’s perfect for the needs of anyone needing to get a -24 LUFS radio mix to -18 LUFS for podcast distribution!
If you have the newer version, here are the steps you should follow:
- Open the Match Loudness window.
- Drag your file from the File window to the Match Loudness window.
- Click on Match Loudness Settings to open the setting window and choose “ITU-R BS.1770-3 Loudness” from the dropdown.
- Select the “Use True Peak Limiting” box if it’s not already selected.
- Make sure the other settings are as so:
- Click Run!
Thanks to Paul Figgiani for pointing me to the new version.
There are other tools recommended in one of Jeff Towne’s podcasting articles at Transom, like Auphonic, which is definitely worth a look. Many of these tools replicate the exact same steps we just did — but in fewer mouse clicks. Also, if you can afford it, iZotope offers a couple of products that will do this step for you very easily, iZotope RX and RX Loudness Control, and their processors sound great. I highly recommend them.
I’ll leave you with one more GIF: