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Signum Audio's Bute Loudness Analyser Plugin (official thread)

More info / register for a trial here:


We are Signum Audio, a new developer based in Edinburgh, Scotland. We have just released our first plugin - the Bute Loudness Analyser.

Bute comes with a customisable warning system, resizable window, DAW synchronisation, re-metering of edits to update integrated loudness and loudness range, Meter history that can be navigated and zoomed in/out, and a multitude of meter ballistics.

Bute supports a wide range of presets - and we intend to keep updating the list. Currently, Bute offers the following presets...
Traditional: Compatible with all revisions of ITU-R BS.1770 and fully supporting (including deprecated versions) EBU R-128, ATSC A/85, OP-59, ARIB TR-B32, AGCOM 219/09/CSP
Digital: Netflix, Spotify, Youtube, Apple Check, Hulu and TIDAL.

We will continually update Bute with new features and presets.

We would like to hear people's feedback and suggestions for updates!

Equal loudness contours

Equal loudness contours - A set of curves of equivalent loudness, which model the ear’s frequency response throughout the audible spectrum. The curves, obtained from actual testing, show how much more sound power is required at one frequency than another to obtain a sound of equal loudness. The results show that the human ear is less sensitive to sound at the extreme high and low frequencies.

Equal-loudness contour

An equal-loudness contour is a measure of sound pressure (dB SPL), over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon, and is arrived at by reference to equal-loudness contours. By definition, two sine Wavesof differing frequencies are said to have equal-loudness level measured in phons if they are perceived as equally loud by the average young person without significant hearing impairment.

Equal-loudness contours are often referred to as "Fletcher-Munson" curves, after the earliest researchers, but those studies have been superseded and incorporated into newer standards. The definitive curves are those defined in the international standard ISO 226:2003, which are based on a review of modern determinations made in various countries.

Mastering Loudness Help

hello i am using izotope ozone 7 to master my original songs and am having trouble with the overall loudness or dynamics of the things i master. for example when i listen to my reference tracks and turn up the volume on my headphones or monitors, i have no problem with distortion or have any problems with irritating my ears. the masters of the songs I'm trying to emulate sound crisp and clear no matter the loudness or volume i set. on the other hand, the things I'm mastering sound okay at a regular volume level, but when i turn it up on my headphones they start to irritate my ears. and if i turn down the master, it will sound quieter overall in comparison to my reference track. does anybody know why this happens and can let me know what I'm doing wrong? thanks!

The loudness wars killing our reputation

I had a band in to make their ep in my studio in november last year. As I run a little one-man-studio in my sparetime I try to work with bands as smoothly and nicely I can while doing all the stuff myself. I depend on them to get the feeling of coming in having a great time while recording some music so that they might spread the word around of my little studio. Now as a small project studio I offer my clients a complete finnished mastered record at a very low price so that young kids would be able to afford to make their own record without spending thousands of dollars. That is my vision.

(Yes, I know that it's not so good to master yourself due to the same ears, equipment etc.)

Well, with my latest project a band with years of experience came in and some of the members had a few records in their pocket already, so they knew how everything worked. I told them that for the price they will get a finnished mastered CD at a standard NON loudness war rms level of around -10 to -8db. I finnished the project at -9.7db rms but they wanted the mixdown so that they can compare the mastering from other places. So I gave them the files, waited a few weeks and checked back with them how it had gone with their ep. They had chosen a mastered version from a big commersial studio and I asked if I could get a copy to compare with my version.

As I got to my studio I started analyzing and got chocked by the levels...they where at -6db rms and all the life was gone. So I got in touch with them again to hear of why they chose that master. I already knew the answer...

So I started thinking, how are guys like me who like dynamics supposed to keep a good reputation when the big studios are still squashing the song? Am I doomed to start pushing the limiter, release it and forget about it? Spotify has since the beginning of their musicplayer had a volume control built in to get all songs the same level for the listener. So the loudness wars are pointless there...I recently read that itunes since this year (? Or last year, can't remember) have built in a similar setting to get levels more to be the same. Still records today are being squashed lifeless by the big companies. When will it stop? And am I better of mastering at -5db rms to keep customers happy and to be a bit louder than the big studios? This is sick!

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The Loudness War Has Been Won: Press Release

14 Oct 2013

Orlando, Florida: “The debilitating loudness war has finally been won,” said mastering engineer Bob Katz on the eve of the Audio Engineering Society (AES) Convention in New York City. The last battle will be over by mid-2014.”

“I have just completed loudness measurements of iTunes Radio using iTunes version 11.1.1. Tunes Radio’s audio levels are fully-regulated, using Apple’s Sound Check™ algorithm. This is a very important development,” Katz said.

During several hours’ testing, Katz measured the output level of several stations, and concluded that each song’s loudness averages -16.5 LUFS, within better than 2 dB, usually plus or minus 1.5 dB. The Apple release notes state that version 11.1.1 “improves stability”, which he interprets as having solved some loudness regulation issues which were present in the previous iTunes release.

It is clear that music producers want their music to sound as good as possible on the nascent but already popular iTunes Radio platform, given the many listeners instantly available. This immediately opens an opportunity to curtail the loudness race within the next few months. Added Katz, “The way to turn the loudness race around right now, is for every producer and mastering engineer to ask their clients if they have heard iTunes Radio. When they respond in the affirmative, the engineer/producer tells them they need to turn down the level of their song(s) to the standard level or iTunes Radio will do it for them—and not always in a pleasing way. iTunes radio will not just ‘turn down the volume,’ but may peak-limit the important transient peaks of the material and make the song sound ‘smaller’ and less clear than its competition.”

Katz suggests, “The engineer/producer should also tell their clients to turn on Sound Check in iTunes to hear their music exactly the way they will be broadcast on iTunes Radio. This makes all music played in iTunes, whether it be on IOS devices played while jogging, connected in the car, or on the desktop computer, perform consistently. It’s a revolution in the making, with instant positive results.“

Katz’s discoveries show that current squashed and smashed pop releases are being attenuated more than 7 dB in order to make their loudness equal to that of more-conservatively mastered releases. In other words, true peak levels of current pop songs are as low as -7.8 dB below full scale! “There is so much available peak headroom now in iTunes Radio that anyone who wants to master their songs with more conservative levels and prefers higher peak-to-loudness ratios will produce music with immediate loudness and sound quality advantages, compared to what’s being played out there now. The cream will soon rise to the top. The music will sound better, even a bit louder, and will attract more listeners. iTunes Radio is already so popular that it will end the loudness race by force majeure. This development is a great opportunity for producers to explain and demonstrate to their clients how to make their songs sound better on iTunes Radio and everywhere else.”

Sound Check is on by default in iTunes Radio and cannot be turned off. However, currently, song files which are on the computer or the iDevice are not loudness-regulated by default, so consumers and musicians who listen to iTunes Radio will quickly discover that Radio sounds more consistent than their playlists, that they don’t have to turn their volume controls up and down when listening to Radio. iTunes Radio also reveals that overcompressed songs sound worse, and not louder than their competition. Therefore, it is imperative for producers and engineers to educate clients to turn on Sound Check so they can hear what their songs will sound like on Radio, and for better listening. “Magazines, newspapers and other media outlets should encourage their readers to turn on Sound Check to make their devices conform with iTunes Radio,” said Katz. “All it takes is a little educating and self-discovery.”

“There will be still some skirmishes, but the main battle has just been won. Producers, engineers and musicians will ultimately discover this news themselves, but journalists and producers can hasten the close of the war, starting right now.” To discuss this important event, Katz invites musicians, producers and engineers to join the free discussion forum at

The discovery that iTunes Radio may be regulated with the Sound Check algorithm was made by engineer Robin Reumers of Galaxy Studios, Belgium, on September 20th. Reumers then began a discussion with fellow loudness researchers Thomas Lund of TC Electronic and Bob Katz of Digital Domain Mastering. Katz immediately made measurements and found some iTunes Radio Stations that were inconsistently regulated, and he suggested that iTunes Radio might not conform to Sound Check. However, the maintenance release of iTunes opened up a possibility, and on October 15th, Katz tested iTunes 11.1.1 and confirmed that Apple appears to have conquered the loudness inconsistencies. Reumers pointed out that this must mean that Sound Check metADATa is being broadcast on iTunes Radio and that Apple had to tweak the receivers in order to properly react to the metADATa. Apple does not normally comment on their technical data or procedures, leaving the task of confirming measurements to the audio community.

“I urge readers of this press release to enter into discussion on the forum at,” said Katz. “Especially if you have any information on Apple’s technical practices. The forum will serve as a central meeting place for producers and engineers who want to see the loudness war end as quickly as possible.”
Contact: Todd Hays or Mary Kent, tel. 407.831.0233 or write