Every time I talk with my friend John Kellogg, I learn something new. John’s the vice president of Advanced Strategic Solutions for Xperi, parent company of DTS. That basically means he’s a liaison between Xperi and the music and movie production communities, a position he previously held for Dolby. John spends a lot of time in recording studios, and has a very good one of his own, too, so he’s always up on the latest trends in pro audio. Thus, when he recently told me, “Oh, the loudness war’s over; it’s all LUFS now,” I had yet another of the “Wait . . . what?” moments common to our conversations.

As John explained, the shift toward streaming music platforms and away from CD has increasingly made streaming services the gatekeepers between music producers and music listeners—a role formerly held by CD mastering and production services, and still held, to some degree, by radio stations. Once an artist or record company hands their digital music files to a streaming service, the streaming service then decides how best to present them.

John KellogJohn Kellogg

Except perhaps for niche services catering to audiophiles, music streaming services strive to keep a broad spectrum of customers happy. One way they can do this is by adjusting the volume of individual music files so that playback level remains fairly consistent from tune to tune and album to album, so listeners don’t need to adjust the volume—something that’s especially important for curated playlists featuring multiple artists. Typically, this feature can be defeated—for example, Amazon Music HD and Spotify have an option to turn volume normalization on and off—but the apps usually have volume normalization on as a default.

To implement volume normalization, one measures the average level of a music file, then adjusts the volume for that file so its average volume matches a certain target, such as -15dBFS (i.e., 15 decibels below the maximum possible signal level, or full scale). Volume normalization has typically been done using RMS average level measurements spanning the full audible spectrum. More recently, volume normalization has been done using LUFS measurements, which were standardized in 2011. LUFS stands for “loudness units relative to full scale,” and it’s designed to reflect the fact that humans don’t sense all frequencies of sound equally—a theory embodied in the equal loudness contours, better known as the Fletcher-Munson curves.

LUFS incorporates K-weighting, which combines two filters. One filter compensates for the acoustical effects of the human head; it’s a shelving-type treble-boost filter that starts kicking in at 500Hz and levels off at +4dB above 4kHz. The other is a high-pass (bass roll-off) filter with a -3dB point at 60Hz and a slope of roughly -10dB/octave. By measuring average level with these filters in place, LUFS provides a more accurate assessment of how a human will perceive the average volume than a simple broad-band RMS or peak-level measurement can.

A LUFS value reflects the difference between full-scale (or 0dBFS) and the average weighted loudness. So a LUFS value of -15 is 15dB below full-scale, after the weighting filters are applied.

Back in the days when CD changers, early digital music file players, and radio stations served up our music, record producers and mastering engineers couldn’t be sure how loud the tunes preceding and following theirs on a playlist or radio program would be. But they all wanted their recordings to sound at least as good as everybody else’s—and as anyone who’s conducted controlled listening tests knows, the human ear tends to perceive a louder music source as sounding better. This resulted in the “loudness war” of the last 20 years or so, where mastering engineers (often at the insistence of record companies) would heavily compress a recording’s dynamic range so its average level might be just a few dB below full-scale. Thus, a tune would have an average loudness at least as loud as the previous or next tune—but its dynamic range would be so compressed that the impact of loud transients (encountered in drum hits, bass-guitar slaps, etc.) was lost and the music sounded much less lively and realistic.

LUFS targets for streaming services are typically somewhere in the mid-teens: for example, Amazon is -11, Apple Music is -16, and Spotify is -14. If a file mastered in the peak of the loudness war era for an average level of, say, -5dB RMS, is played through these streaming services with the volume normalization on, the service will bring the volume down to its LUFS standard. The file won’t sound any louder than any other, but it will still suffer the sonic degradation of extreme dynamic-range compression, and its peak loudness will actually be lower than that of a less-compressed file.

Knowing that their files will be played back with the same reasonable average loudness as everyone else’s gives recording and mastering engineers the freedom to incorporate more dynamic range into their productions. They may still want to master with higher LUFS values for CDs, which will necessitate more extreme dynamic-range compression. But considering that the CD is no longer the primary focus for most of the music industry, the record company may not wish to pay the additional mastering costs—and the CD will sound better at the streaming-friendly LUFS value. It’s quite an ironic twist that the popularity of streaming services may end up making CDs sound better, isn’t it?

Reaper Waves

To see the difference among typical LUFS values, I ran a recording through the Waves WLM Plus Loudness Meter plug-in, which is used with Reaper digital audio workstation software, and adjusted the level and dynamic range compression to hit -14 LUFS (the Spotify target) and -6 LUFS (a value that might have been common in the heyday of the loudness war). The recording I chose was “Aprender,” a tune I recorded with saxophonist Ron Cyger for our upcoming album. The reason I chose this one wasn’t purely for shameless self-promotion; it was also because I needed an unprocessed mix that I knew hadn’t gone through dynamic-range compression.

The graphs here show the waveform for the first two minutes of “Aprender” at different LUFS values. The original, uncompressed mix (top graph) had a measured average loudness of -19 LUFS. I then applied a light 4:1 compression ratio so the signal peaks wouldn’t clip (i.e., exceed 0dBFS) and raised the level by 5dB, which gave me a Spotify-optimized average loudness of -14 LUFS (middle graph). Finally, I applied a heavier compression ratio of 9:1 and raised the compressor threshold to achieve average loudness of -6 LUFS (bottom graph), which is more typical of what we’d hear from loudness war-era masters.


You can see how the -14 LUFS version still has a good amount of dynamic range. In fact, the compression I used for that version is comparable to what I use for most of my music productions, and it’s similar to what I used for the soundtrack of the YouTube video in the link above. But the -6 LUFS version has very little dynamic range. I listened to it only briefly, but from a dynamic standpoint, it sounded something like what you hear when you play music from an AM radio station through a high-quality stereo system. Of course, what you see here represents just a quick attempt by someone with limited mastering experience to hit certain LUFS values. A professional mastering engineer would know the right tricks and tools to get better sound at -6 LUFS—but still, it’s probably not going to sound great.

I guess you can sum all this up by saying that the loudness war is over, and audiophiles won!

. . . Brent Butterworth
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  • This commment is unpublished.
    Brent Butterworth · 1 months ago
    @Soundstagenew2021 It's not an error. The loudness war had nothing to do with listener behavior (i.e., turning off normalization), it had to do with mastering behavior. If I erred, it's in suggesting there's something new happening here. It's common to see assertions among audiophiles that the loudness war is still raging, but if you peruse the AES E-Library, you'll find that the general consensus among professionals is that the loudness war peaked around 2004 -- four years before mainstream press even started covering the trend. In the 2014 JAES paper "About Dynamic Processing in Mainstream Music," the authors state that while average RMS loudness is 4 dB louder in post-2004 recordings compared with pre-2004 recordings, average crest factor since 2004 has decreased by only 1.4 dB. That's not much, and it can easily be explained by evolving styles and tastes, and by the fact that almost all Top 40 music is produced entirely in a DAW with little or no acoustic recording of instruments.

    I hear audiophiles complaining about the loudness war and dynamic range compression all the time. But I have to wonder how many of them really know how to recognize dynamic range compression, and how they learned? Do they have experience using compression and limiting? Do they appreciate why it's used? Complaining about the state of the recording art and deriding the work of audio professionals seems to have become part of the audiophile identity, but as I've noted many times before, too few audiophiles make the effort to gain in-depth knowledge of audio -- they just read high-end audio publications and forums, rather than reading technical books or joining AES.

    Case in point: see below, a guy who either didn't read or comprehend my article, and who definitely didn't read the article he linked to.
  • This commment is unpublished.
    Soundstagenew2021 · 1 months ago
    Hi Brent, I'm not sure how you can say "I guess you can sum all this up by saying that the loudness war is over, and audiophiles won!" when with Apple Music (only something like over 60 million users and only #2 behind Spotify...) normalization is OFF by default and in both Spotify and Apple Music cases (over 300 million users) normalization can be easily turned OFF by the user. There's thousands of posts on Spotify forum and Reddit of users saying normalization turned OFF sounds better (when we know it's just louder). The only way this loudness war can be declared over is when normalization is ON across the board and there is no way to change this setting by the end user.... Given this minor error, I think your article needs to be updated. It's probably a few years pre-mature to declare this over. Things are moving in the right direction obviously but a bit of simple testing will show we're not there yet...
    • This commment is unpublished.
      Brent Butterworth · 25 days ago
      @Soundstagenew2021 Saying the loudness war is over doesn't mean no one's going to create highly compressed mixes. Of course they will continue to do that. It's part of the sound of certain genres now. The "war" notion originally came from the idea that producers and mastering engineers felt they all had to be at least as loud (i.e., compressed) as the previous tune and the next tune -- they were "at war" with each other to see who could be loudest. As the most popular music distribution outlets now effectively penalize highly compressed mixes, there is no longer any need for producers and mastering engineers to be "at war" with each other.
    • This commment is unpublished.
      Soundstagenew2021 · 26 days ago
      @Soundstagenew2021 Correction discussion is for 2017 album 'Colours', so not new. But if you follow that thread, some Grammy nominated pro's there, there is disagreement about loudness war. One pro mentions in that thread: 

      "With regard to loudness, remember if the .wav ain't square the song ain't there."

      So there's no universal agreement about loudness war being over. From the pro's.

    • This commment is unpublished.
      Soundstagenew2021 · 26 days ago
      @Brent Butterworth Here's a discussion among pro's for an album that just won best Engineered album... The one mastering engineer you interviewed for this article may think the loudness war is over but other pro's don't:


  • This commment is unpublished.
    Brent Butterworth · 1 months ago
    @Jeremy W Bob Katz didn't author that article and doesn't address anything in it. The first paragraph merely quotes him as saying, "The loudness wars are over," and the article mentions him only a few times after that -- a very small part of an article that's somewhere around 9,000 words with the sidebars. The article basically agrees with Katz's statement and what I've said, and presents many examples of best practices employing the then-new volume LUFS standard and normalization practices. Yes, there are lots of overly compressed mixes still out there, but it's likely that the popular ones will be remastered, and as the article points out, it will be increasingly less likely that these mixing practices will continue into the future.
  • This commment is unpublished.
    Jeremy W · 1 months ago
    Yes the Loudness Wars is over and loudness over dynamics won the battle. While I appreciate streaming services adopting a loudness standard (in this case LUFS) it does not solve the issue that the Loudness Wars created. I can a modern slammed recording and achieve the same thing streaming services are doing by putting a track through Audacity and using the 'Normalize' feature. Still sounds terrible, just lower volume. The main issues still lie with modern recording practices all the way up to the mastering phase. LUFS standards need to be present in all stages of the recording process in order for this to be corrected, I believe Mastering Engineer Bob Katz addressed all of this in the following article published 7 years ago: https://www.soundonsound.com/techniques/end-loudness-war
  • This commment is unpublished.
    Daniel · 2 months ago
    @Brent Butterworth It's enough to go to youtube, right-click on a video and select "Stats for nerds". This will show video statistics and one of the things there will be "Volume / Normalized". I just clicked through a few videos on youtube's "Pop Hotlist" list and most of the things there have loudness 5 dB and more over the target.
  • This commment is unpublished.
    Brent Butterworth · 2 months ago
    @Mauro I'm planning on doing more research into this, doing measurements on actual streams from streaming services. On Doug's FB posts, I've seen commentary from pros saying, in effect, yeah, this is a trend, but a lot of new mixes are still very crunched.

    This Loudness War site has always seemed a little dicey to me. It relies on reader submissions, and thus isn't a valid sampling. It's also taken almost entirely from CDs and downloads (although the sources of the downloads aren't specified). What I dislike the most, though, is that it seems designed to inflame audiophiles' sense that the record industry is victimizing them. The audiophile publications already do a great job of that! :)
  • This commment is unpublished.
    Mauro · 2 months ago
    @Brent Butterworth Looking at this website with recent albums on top doesn’t seem to support the hypothesis of the article but I am not sure it is a trustworthy source
  • This commment is unpublished.
    Brent Butterworth · 2 months ago
    @Doug Schneider I haven't found a website that tracks this stuff. I do intend to do some measurements on it in the future.
  • This commment is unpublished.
    Doug Schneider · 2 months ago
    @Brent Butterworth Is anyone in the pro industry more or less "tracking" this to see what's being done? I know there were some dynamic range sites a while back, but is anyone trying to act like a watchdog?

  • This commment is unpublished.
    Brent Butterworth · 2 months ago
    @Mark Waldrep Hi, Mark. You're citing a 2002 album, which was certainly in the midst of the Loudness War. Of course, most of those masters of that era are still available in CD or digital download. But now that the primary method and technology of music distribution has changed, and in 2011 we got an industry standard for average volume measurements, maybe it's changing? There's no reason to slam those files if they're going to go on Spotify and your peaks top out at -10 dBFS.

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