See here
http://en.wikipedia.org/wiki/Loudness_warand here
http://mixonline.com/mag/audio_big_squeeze/and here
http://www.barrydiamentaudio.com/loudness.htmand here
http://www.broadcastpapers.com/radio/OmniaHDRadio10.htmand here
http://etvcookbook.org/audio/ntsc.htmland this from
http://www.soundmirror.com/articles.htmlCurrent Trends in Mastering: The Loudness War
June 2003 Performer Magazine
One of the recent trends in the world of mastering is what we mastering engineers call "The Loudness War." In the past couple of years there has been a steady increase in the "loudness" of commercial releases from virtually all the major labels and in almost all styles of music. We are going to take a look at the history, the listener's perception, and the pitfalls associated with this trend, as well as investigate how the marketplace pressures artists to turn their great record into merely the next loudest record.
History
As with most things in the recording world, we need to take a quick look back to get some perspective on current mastering practices. The term "mastering" comes from the earliest days of recording. It was the process of cutting a groove into a lacquer coated disk that was the "master" from which all the replicated records were made. Due to the technical limitations of the LP record (remember those shiny black things that spun and you actually put a needle in the groove?), the mastering engineer had to alter the signal from the tape to get the most out of the format. The tools that early mastering engineers used are the same as the tools we use today, namely, frequency equalization (EQ) and dynamic range compression/limiting. While mastering was originally a simple transfer of tape onto disk, over the years it developed into the creative process we know today. The mastering engineer is now the final person making creative or artistic decisions on the CD before it becomes the finished consumer product. (That's another whole topic, but we'll leave that one alone for now.) He or she must make all necessary changes that mold a diverse group of tracks into a single cohesive entity. The mastering engineer must also transform the raw mixes into a commercially viable product capable of attracting the attention of radio program directors and record company A&R managers. This brings us to the topic of the moment: The Loudness Race.
How do we perceive loudness?
Psychoacoustics is an entire field of research that deals with how humans perceive sound. Although these scientists spend their careers studying how we react to sound, we are only going to 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 a 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 is much higher. One generally accepted rule 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 his attention. This is great for a single, but as we have found in many of the current crop of hypercompressed CDs, this "full on all the time" approach ultimately fatigues the listener. A variety of dynamics will keep listeners on their toes and make them continue listening. The film community has used this dramatic dynamic 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.
The origins of the loudness race
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 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 be the loudest record was on!
With the advent of the compact disc in the 80's, a whole new trend was started. The CD's increased dynamic range and absence of rumble, ticks, and pops caused the artistic community to embrace dynamic range. Many extremely dynamic titles were produced in this period. Several record companies even went so far as to put disclaimers on a CD saying they were not responsible for speaker damage caused by the extreme dynamic range of the particular disc! With the release of the first 5-disc CD carousels with shuffle play in the late 80's, the race started all over again.
Many mastering engineers consider the early 90's the golden age of mastering, because 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, like Nirvana's Nevermind or the Smashing Pumpkins' Siamese Dream, 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.
Moreover, the formats and the locations that we listen to music have changed. 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/iPod. Because of the limited dynamic range and frequency response inherent in these systems, the data compressed versions of the music sound better. Also, compressed music sounds better in the car, because it gets the sound up over the ambient motor and road noise. Whereas in the early 90's we were mastering records with the assumption that they would be listened to on a consumer playback system in the living room, today we need to take into account the other locations people listen to music.
How did you make it that loud?
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. Current 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. As with all powerful tools, it has become incredibly easy to do more harm than good.
I am frequently asked, "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. But there are several things to think about when you want to make your record loud. I always tell people, "It