How loud should a song be? What is considered is loud? In this article, iZotope Education Director and professional mastering engineer, Jonathan Wyner discusses loudness. From how perception influences loudness mastering audio, to best practices for loudness in a variety of formats—streaming, vinyl, CD, and beyond.

Over the last 20 years, the phrase “loudness wars” has become enmeshed in conversations about music and audio, and for good reason. 

We’ve been hearing the phrase for decades, long before we had digital limiters. We now have limiters that allow us to push level in a way that we never could before. With or without these tools, the idea of making more impactful and compelling records that contain good amounts of dynamic contrast and loudness isn’t going away. 

Given that this is the case, we should dig a little deeper into the craft of music production to think harder about what contributes to the experience of loudness.

What Do We Mean When We Say Loudness? 

Let’s first unpack the concept of loud. 

There are two key considerations in loudness—average level, and the distribution of energy across the spectrum. If you make a record focused in the upper mid-range, it’s going to be louder by definition (if the average levels are the same) than a record containing more low-frequency information, proportionally speaking.

When we talk about dynamics—dynamic range or musical dynamics—very often we’re talking about contrast. We mean that something’s louder than something else—a nearby truck horn is louder than one at a distance, a verse is generally not as loud as a chorus, and the chorus is louder than the verse.

When the time comes to consider pushing level in a mix or master, we need to keep this dynamic contrast between sections in mind. Is there enough of it? When we push level, will it diminish the sense of dynamic contrast? If we are concerned about the perceived loudness overall, where is the energy focused? Is it focused in such a way that the record will appear loud enough to the listener? Always consider this contrast.

How Loud Do I Make My Record?

Loudness in mastering doesn’t exist in a vacuum. The decisions you make from the very first moment you commit to an arrangement to the structure of your mix all have implications regarding the choices you make when mastering. This is why it’s important to take a look at what’s in a mix. Any decisions made there will impact your approach to the master and the overall result. 

For example, if you have a really hot drum stem compared to the rest of your mix, your crest factor—the difference between peak and RMS levels—might be high and you’ll likely have a hard time getting your record to be as loud as it would be if that hot drum bus were lower. If you have a high crest factor and you push level into a limiter, the limiter will push back sooner and harder because your peak levels will drive it harder than if the hot drums were sitting a bit further back in the mix. 

Of course, if you’re mixing and mastering your own work, you have more control over the adjustments—you can revise these decisions before you commit to a mastering treatment. If you find that your limiter is working too hard, maybe it’s an opportunity to return to the mix stage and pull down your drum stem a little, remove a little low end from your drum kit to help lower your drum level and ensure the limiter doesn’t work as hard. 

How Loud Should My Master Be For A Specific Platform?

How loud should your master be if you’re distributing to Spotify, Apple Music, Amazon Music, vinyl, or whatever today's latest, greatest platform is? That might be the wrong question to ask. I think the question should be:

Can I make this louder and have it sound at least as good—if not even better—than it sounds now?

Adjusting the way we conceptualize good and loud is where we can start to truly develop the craft and skills of mastering (and mixing)—managing the tradeoffs, recognizing when we've gotten to the place where the music is as hot on the meter (loud) as it can be, sounding as good as it can be so when it's adjusted for playback—either turned down or if we have to turn it up for certain kinds of applications—it will still sound as good as we can possibly make it sound in that moment.

Best Practices For Choosing A Level

While I hold to the statement that there is no recipe for the exact level for any given record, there are some best practices I can offer that are connected with different varieties of distribution. 

• Streaming services: If you're creating a master that's going out to a streaming service, having your peak levels sit at minus one is a best practice. Learn how to master specifically for streaming services in this Are You Listening? episode, or get more tips in this article.

• Vinyl: If you're generating a master that's going out to vinyl, it's a good idea to relax the level and turn off your limiter altogether. Don't worry about peak level. Worry more about getting it to sound as good as possible without the benefit of a peak limiting. The reason for that is when you peak limit, you generate something that looks an awful lot like a square wave at the top of the dynamic range, and vinyl cutting styli are not very good at cutting square waves. So for a vinyl cutting engineer, they're happier with a level that's a bit lower than what you would generate for a digital distribution format.

• CD/non-normalized digital formats (MP3, AAC, etc.): You probably want to let your level come up a bit because that's the context where measuring average level or loudness from one master to the next is something that's going to be done without any intervention. There will be no further loudness normalization on playback. So those are formats where we think about getting the level up higher. 

At the end of the day, where the level resides on a meter at the output on your mastering chain and the amount of musical dynamic is up to you. There is no absolute value to point you to, but rather a range of values that make sense for specific genres. For example, you can intuitively understand that a classical record might have a lower integrated value than punk rock or electronic record.

Conclusion

I hope these thoughts about loudness have been helpful. If you take what you’ve learned here, you'll begin to understand the relationship between the use of the tools and some of the concepts that we're trying to navigate. All of these things play together. 

We start with the notion of genre, wind our way through all of the creative decisions and the technical decisions, and then consider output, how the music is going to land in the marketplace and on the ears of the listener. Our job as mastering engineers, ultimately, is to try to connect the audience with the artist's vision. It’s the same goal that the producer has and the same desire that the artist has. So that's why it's important to think holistically about the entire process when we're trying to navigate issues such as loudness.