The so-called “Loudness War” was a trend in the early 1990s of increasing recorded music audio levels to the point where sound quality was sacrificed for loudness. Audio techniques such as compression and equalisation were key weapons in this war, and the mastering engineer was frequently leading the charge.
The battle continues for many commercial dance music producers but, otherwise, the Loudness years are a time most sound engineers would sooner forget. These days, those trained in the delicate skill of mastering are more likely to be accused of doing little or nothing to a track rather than making Sufjan Stevens sound like The Prodigy.
"I see it as a return to musical/audiophilic values," says Rich Duckworth, a lecturer in music technology at Trinity College Dublin. "Some of this has been driven by tastes and an interest in vintage formats – these tend to be more interesting, dynamically speaking."
As Duckworth puts it, the custard might have been “overegged” in the digital era. “We’ve now entered a postdigital era which uses hybrid analogue/digital set-ups and a more sensitive approach to both production and mastering.”
Master of all
"Mastering" is the final creative step in the recording process. "It's about refining the sound to allow a musical project to realise its full potential, and optimise the finished product for all possible environments," says Jeff Lipton from Peerless Mastering in Boston.
Lipton has worked on music by Arcade Fire, Bon Iver and LCD Soundsystem, to name just a few. “It’s about getting all the songs to work together as a cohesive album.”
The technique became increasingly necessary after the dawn of multitrack recording.
"If you have 10 songs on an album that were recorded in four different studios, each song could have a different volume, tone and equalisation to the one preceding it," says Gary Powell, senior lecturer at the Butler School of Music at the University of Texas at Austin. "Without it, this can be quite a shock to the ears. Mastering 'smooths' out the differences."
The term doesn’t refer to one process but a series or chain of actions. Says Duckworth says: “The mastering engineer works in an acoustically designed room that [typically] contains a pair of high-quality speakers and a mastering console, which houses a suite of analogue and digital tools.”
There are too many tools involved to list them all, but a few are universal. “Mastering is typically done with high-end equalisers, compressors, limiters, levelers and sometimes harmonic processors,” says Lipton. “Good mastering rooms are incredibly, acoustically accurate and allow the mastering engineer to make the best possible decisions for the material.”
The great leveller
Levelling refers to a process whereby tracks are adjusted for volume so that the dynamic of each is relatively consistent with respect to the others on the album. “This ensures that no one track will stand proud of its neighbours, dynamically speaking,” says Duckworth.
Compression, meanwhile, refers to automatically attenuating (or reducing the level of) the loudest moments on a track.
“This process, somewhat paradoxically, allows the engineer the latitude to raise the level of the track to create a louder, more present effect,” Duckworth says. “In its most extreme form, this phase of the process can be used to create an obnoxiously loud mix through the use of dedicated compressor/limiters called track slammers.”
The treatment is often used on dance and commercial rock music and was a key component of the Loudness War.
All things equal
Because no recording studio will capture audio perfectly, tracks usually need some type of equalisation (EQ), or tonal balancing. There are two types: corrective and augmentative.
“Corrective EQ is used to remove unwanted frequencies,” says Duckworth. “For example, if the mix appears too ‘muddy’, one might remove some low-midrange frequencies. Augmentative EQ is used to flatter the content that is already there. If a track already sounded great but needed a little more ‘sparkle’, one might boost some high-frequencies – perhaps add a little ‘air’ to the mix.”
Terms such as “sparkle” and “air might sound like things are getting a little high-falutin in the studio process. Still, an album’s end goal is to be a polished mix that offers a similar perceptual effect to the typical listener across various playback devices, be it an iPod, 12-Inch or car stereo.
“It is complicated,” says Duckworth, “because the human ear-brain apparatus is complex and nonlinear, and there are significant factors introduced by enculturation as well.”
The subtle and minor refinements made at the mastering stage are what make it harder to grasp. “But it’s those subtle and small, refined changes that add up to a greater whole,” says Lipton. “Mastering makes things sound clearer, warmer and more alive, but it doesn’t usually change the essence of the material. That sounds like magic to many people.”
Also, there are limited options available once a track reaches this final stage of production. “The mastering engineer doesn’t have multiple tracks to work with like at the mixing stage,” says Powell. “They have two tracks, a stereo file, one left and one right. There is only so much they can do.”
Confusion around mastering isn’t helped by a widely used misnomer. From Bowie to Zeppelin, “remastered” versions of classic albums are released to the delight of diehard fans.
“In this context, ‘remastering’ actually refers to ‘remixing’ an album,” says Powell. “If you have access to the multitrack takes of an old song, an engineer can go back into it with new digital tools to repair mistakes in the original recording, fix tuning issues etc.”
Master’s master
There are many types of mastering engineer: some work in a niche way and use sophisticated digital analysis tools to correct or enhance tracks. Others might use more organic, analogue-based approaches that rely on intuition and feel.
“Mastering engineers are like hair stylists,” says Duckworth. “They can develop a select customer base of top artists by offering a niche product and/or a special understanding of a certain genre of music.”
Like a hair stylist, however, master engineers are only as good as the music they have to work with. “Each part of the recording process is dependent on the part that came before,” says Lipton. “To get good tracks, you need good musicians. To get a good mix, you need good tracks. To get a good master, you need good mixes.”
Given that AI technology will eventually take over many of the tasks now performed by humans – including those requiring reasoning and judgment – an activity already as digitised as music production won’t be immune to machine learning.
“Engineers already rely on analysis tools to predict and optimise equalisation curves, so we’re only a few years or months away from a completely automated mastering process,” says Duckworth. “I foresee a multitiered industry where traditional mastering, online mastering and automated mastering co-exist side-by-side.”
Like many other work-related AI scenarios predicted for the future, it’s unlikely that machines could manage the work of a mastering engineer autonomously.
“Right now computers are still very bad at analysing emotion, while we are very good at it,” says Duckworth. “The human ear-brain system is much more complex than the most sophisticated computer. So I think we’re a long way from a suite of modelling algorithms that will fully convince the auditory system.”
Let’s all breathe an audible sigh of relief.
