Thursday, March 11, 2010

Audio Mastering - Dynamic Range Explained

What is audio-mastering, what does it do, is it necessary, and most importantly, why is audio-mastering important to an independent musician?  Before mastering my new double-album Animist, I spent a lot of time trying to answer these questions.

Simply put, audio-mastering makes your music louder.  In other words, mastering is the difference between the volume level of (insert any major commercially released album here) vs. the volume of the album you recorded on your laptop or 4-track recorder.  If you are not sure what I mean, just compare the volume of your favorite major label CD vs. the volume of a CD you recorded yourself.

Although the subject of mastering is much more complex than this, volume level is good place to start.  Volume, or how loud a CD sounds is directly tied to the dynamic range of the recorded audio.  Dynamic range is simply the range in decibels between the softest and loudest parts of a recording.  However, it is important to remember that dynamic range is measured in the aggregate, i.e the dynamic range of a particular recording is based on a collection of the peaks and valleys of the audio signal as opposed to anyone particular peak or valley.

For example:
The difference between how loud a Frank Sinatra record sounds (dynamic range of about 12 decibels) versus the heavier, more aggressive recordings of Tool (dynamic range of about 6 decibels) is an example of how differences in dynamic range changes the listener's experience.  In other words the Tool CD sounds much louder than the Sinatra CD because the overall range between soft and loud is smaller making the entire CD sound louder.  If you are still confused there are some great visual examples of similar comparison available on YouTube.  One of my favorites is available by clicking here.

During the mastering process a mastering engineer will take the bands mixed audio and attempt to make it have more punch and increase the overall volume through the use of compression.  In this case, compression is used to increase the level of the quieter parts of a mix while compressing or limiting the peaks.  During this process the dynamic range of the audio is reduced to make the whole recording sound fuller and louder.  The amount of compression a mastering engineer uses is a large component in how loud or quiet your CD sounds.

Since the digital revolution of the early 90's there has been a push to make all recordings sound louder.  For example, Pearl Jam's 3rd album, Vitalogy, released in the mid 90's has a dynamic range of about 9 db while the Radiohead's most recent release, In Rainbows, has a dynamic range of about 6 db.  While you may be thinking, who cares I love both those records, it is important to understand how the quest for an ever louder CD is changing not only how recorded music sounds, but also our perception of it.

While a smaller dynamic range increases overall volume it also reduces the overall dynamics.The reason audio-mastering is so important to an independent musician is because you want your CD to sound as loud as those that are commercially released.  The main problem is determining how loud is loud enough and how loud is too loud.  I like to think about it in terms of how much do you want to "squash" your mix.  For example it is easy to make your CD sound louder by using compression to "squash" the hell out of it, but by "squashing" the mix too much you lose the dynamics that you originally intended.

The debate amongst audio professionals in regards to how loud is too loud continues to rage.  Organizations like the Pleasurize Music Foundation are attempting to gather support to standardize the dynamic range of all commercially released music at 14 decibels.  Personally, I am still on the fence as to whether or not 14 db is the appropriate range or whether the reduction in dynamic range is destroying the quality of recorded music because for some genre's the "always loud" sound is exactly what is needed.  However, I do think that is essential that independent musicians have a basic understanding of this concept because you don't want to spend hundreds of dollars having your album professionally mastered only to get it back and be disappointed with the loss of overall dynamic range.

In other words, be aware that some level of audio mastering is necessary to compete with commercially released albums, but one must be wary of taking that quest for loudness too far.

Until next time....

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