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There is an entire field of research that deals with how we humans perceive sound. This is called “psychoacoustics.” These scientists spend their careers studying how we react to sound, but we are only going to take a look at how we react to and perceive loudness. There are two different ways to measure the loudness of a sound, the first is to find the peak level that the sound reaches, the other is to average the sound level over a period of time. The ratio of peak to average level is called the crest factor. In general, our ears respond to the average levels, not the peak levels when judging loudness. An example of this is found in listening to different kinds of music. When you compare the peak levels of classical music with commercial rock, they both peak at the same level, but perceived loudness of the rock music will be much greater, because the average level much higher. One of the generally accepted rules is that the louder sound will always grab our attention, and for short periods of time, sound better to us. This is why when the record company A&R guy is listening to twenty CDs of new bands, the loudest one will grab their attention. This is great for a single, but as we have found in many of the current crop of hyper-compresed CDs, this “full-on, all the time” approach ultimately fatigues the listener and causes them to lose interest. A variety of dynamics keeps the listener on their toes and makes them keep listening. The film community has used this dramatic dynamic content for years to keep viewers on the edge of their seats. Five large explosions in a row do not have the same impact as four little ones and one huge one.
Everyone thinks that this loudness race is a recent phenomenon, however, its roots go back many decades. From the earliest 45 rpm singles, people have been trying to have their product be the loudest record in the stack of records on the record changer. Going back 20 or 30 years, many record companies would send out compilations of new singles to radio stations on a single LP. When producers and artists listened to these, if their song wasn’t the loudest one on the record, they would call the mastering engineer and have them raise the level so as to be competitive. We can all see where this is going, the race to the loudest record was on!
With the advent of the compact disc in the ‘80s, a whole new trend was started. The CD increased dynamic range and the absence of rumble and ticks and pops caused the artistic community to embrace this format. Many extremely dynamic titles were produced in this period. Several record companies even went as far as putting disclaimers on CD released that said that they were not responsible for speaker damage caused by the extreme dynamic range of the particular disc. However, with the release of the first 5-disc CD carousels with shuffle play in the late ‘80s, the race started all over again. Many mastering engineers consider the early ‘90s the “golden age of mastering,” when the decisions made about the loudness of a disc were made for aesthetic reasons and not by marketing people. Many of these records are still alive and kicking today, but if you compare the level of some of the loudest records of the day – Records like Nirvana’s Nevermind or the Smashing Pumpkins’ Siamese Dream – you’ll see that these records are 6 to 8 dB quieter than virtually all the commercial rock today. (Just as a note, 6 dB is perceived half as loud). This trend is not limited to the rock world. Virtually all genres have fallen victim to the loudness war. Hip-hop, R&B, AAA, AC and even Folk/Americana are making records that have all the music squashed into the top 5 dB of a medium that has more than 90 dB of dynamic range.
Also, the formats that we listen to in which we listen to our music have changed, and this has fueled the loudness war. Many people today listen to their music via mp3 and AAC on their computer, in the car and on the Walkman or iPod. These data compressed versions of the music sound better when they are more compressed, because of the limited dynamic range and frequency response inherent in these systems. Also, Compressed music sounds better in the car because it gets the sound up over the ambient motor and road noise. Where as in the early 1990’s we were mastering records with the assumption that they would be listened on a consumer playback system in the livingroom, today we need to take into account the other places people listen to music.
As with most things that have to do with music these days, much of the loudness revolution has been brought about by new technology in the studio. High quality digital limiters and compressors have completely changed the way we think about compression and loudness. In days before these devices, we were limited by the maximum amount of compression, slow attack/release times and distortion for which analog compressors are famous. There was no such thing as a brick wall limiter. However, digital compressors and limiters have none of these limitations. They can look ahead at the music and compensate for any transients that are on the way. It’s important to remember that with all powerful tools, it is incredibly easy to do more harm than good.
One of the questions I am asked all the time is “how do I get my record to sound like the latest and greatest record on the radio?” Unfortunately, there is no easy answer to this question. Most of the records on the radio are productions that cost $100,000 and up. Also, they are done by people with the experience of many records under their belt. There are several things to think about when you want to make your record loud. I always tell people that it’s not how loud you make it, it’s how you make it loud. The reason there is a big difference between the major productions and a home demo is the way that you go about compressing things. I get masters in all the time that somebody has run through the latest and greatest plug-in, but complain that it doesn’t have the impact or punch that the latest million seller has. What I tell them is that to get a record to be loud without sounding squashed, you have to think about it in a systematic way. It all starts when the first sound is committed to tape or disc. Gentle compression at all the different stages of the production (tracking, mixing, and mastering) will yield better results than doing it all at the end, but this is a concept that most beginners fail to take to heart. The analogy I make is with archeology. There are 2 ways to dig up an ancient ruin, with a bulldozer or with small handtools. They both do the same thing, but knowing which tool to chose is the hard part.
I’d like to mention a couple of pitfalls that people often fall into when they are mixing a record. The first is how, when, and why to use a compressor on the stereo mix buss. One thing I get all the time is a mix that has been over compressed before it got to the mastering studio. I ask how the compression was applied, and invariably the answer is that they were comparing the mix to a commercial CD and it didn’t sound as loud, so they compressed to stereo mix at the end of the session to bring the level up. This is a patently bad idea. If you are going to use a mix compressor, it should be part of the monitor chain. It should always be there. All the mix decisions about sound and levels will be affected by the compressor, so switching it in and out, I find, often confuses the matter. If you have any question as to whether or not to use this compressor, I would say do not use it. While the mastering engineer can cure a great number of problems in mastering, the one thing that can never be undone is over compression. Also, your mastering engineer has very specialized tools for stereo compression that can probably do a much better job than the generic compressor at the mix studio.
Another thing to think about is what CD you should be comparing your mix to and why. The thing that you have to remember is that the CD you are comparing you mix to has been mastered and if it is a current release, will be much louder. It is a problem because the mastered version often is radically different from the original mixes. CHOOSE YOUR COMPARISON MATERIAL CAREFULLY!
Once you have finished your mix, unfortunately, this is where there is no replacement for the experience and tools of a mastering engineer. While many people today have access to plug-ins and workstations in their home studio or where they mix, it takes years of experience to realize that if “a lot is good, then too much must be better” school of thought does not apply to mastering. I have seen many perfectly good sounding projects ruined through overcompression. One thing to think about is the set of skills and that your mastering engineer has. A typical mastering engineer sees about 150 to 200 records every year. There is no replacement for the experience of hearing hundreds of different projects in the same controlled environment of the mastering studio. Also, the intimate knowledge of the highly specialized tools in the mastering suite can not be understated. I personally did not feel completely comfortable in the mastering suite for the first 4 or 5 years (in which I mastered about 500 records). The right choices in mastering gives your project the ability to push your project up to the next level, whether it be to make it crushingly loud or to perfect the subtle nuance of the release of a reverb tail.
Mark Donahue is the Chief Mastering Engineer at Soundmirror, Inc. 76 Green St., Jamaica Plain, MA 02130. He can be reached at (617) 522-1412, or you can visit www.soundmirror.com Soundmirror, Inc. is a state of the art, full-service mastering facility, offering superior mastering for CD, SACD and DVD-A.