By explaining something I occasionally experience as a mastering engineer I think I can help people understand some of the detrimental issues that relate to the loudness war in an easy manner. I will often send a master to a client and they will then say the track sounds excellent but they have had a listen to the track and it is not as loud as “X” as a reference. Firstly if loudness is an important factor it is always a good idea to provide a reference track so that the mastering engineer understands this is an important aspect of the audio mastering. My response to the client is often one which explains the non existence of a “loudness button” that exists independently of overall fidelity.
When a mastering engineer masters a piece of music there is a complex interaction of processing components which go to create the overall sonic enhancement. It is rare that one element can be adjusted without affecting another process. Dynamic processes are often related to the frequency content of a mix down and as such are very finely tuned to the tone of the overall audio. You could say the mastering processes (often both analog and digital) are often interdependent on each other. In fact increasing the loudness of the mix is one of the processes which is most dependent on other decisions in the mastering chain. Turning up the volume on an amplifier or hi fi is a very different type of volume increase compared to perceived level increases achieved in mastering. Turning up the volume is not affecting the music intrinsically and you will enjoy the punch, space, energy and adrenaline enhancing feeling the music has to offer. The fact is louder music does tend to bring out physiologically positive responses in humans. Increased perceived volumes in the context of mastering are often based on arresting transient information. ( the peaks in the music - often drums). This directly affects the sense of punch and power in the music because you are taking away the peaks and creating more of a blanket of sound without any dynamic peaks. Of course mastering engineers do everything they can to avoid these down sides to the loudness war but ultimately the laws of physics dictate what can be achieved and beyond a certain point music is detrimentally affected. (despite using the best tools)
Commonly when level needs to go upwards the mastering engineer will choose a range of different tools to get the do the job not overly relying on 1 to effect the change. When doing so increased attention needs to be paid to the onset of the following side effects, distortion, loss of detail, increased harshness, change of mix tone, changes to transient punch, change of mix down balances, increased likelyhood of listener fatigue. It is impossible to raise the perceived volume of the music without affecting other aspects than merely the perceived level.
As such armed with this information you should be able to make better decisions about how loud you wish your mastering engineer to master your music. Knowing the trade offs should help you decide a balance between retaining dynamics and increasing perceived volume. All music tracks have a level which comfortably walks the line between the two. If perceived volume is important speak to your mastering engineer before the mastering session commences and discuss the presentation of a reference for volume.
Barry Gardner is chief engineer at SafeandSound audio mastering