How did the Loudness War start?
The Loudness War has been going on since the CD was introduced in the beginning of the 1980s and has increased in intensity up to the present. Even during the age of vinyl discs, the phenomenon existed. But the scope was then limited technically by both the mechanical playback and by lack of digital signal processing technology.
When listening to a track that is only 0.5dB louder than another, the first impression is that the slightly louder track is warmer, more brilliant, and punchier (See: Why is a strongly compressed tracks attractive?). This factor obviously affected each release in the natural competition for better sound. Clients constantly tell their mastering engineers that their tracks must be at least as loud – if not louder – than a reference track release. With the introduction of digital signal processing technology, music can be compressed beyond the frontiers of good taste. This phenomenon has occurred gradually over a number of years and has crept into practically every commercial release, making it difficult to hear significant differences with short, so-called A/B comparisons.
Today the trend has spiraled so far out of control that record label managers are afraid that quieter-mastered releases won't sell, ignoring the warnings of responsible mastering engineers. This has led to releases that sound like white noise and which are as pleasant to the ears as a hard slap in the face.
Here you can see the typical development of loudness from the time of the introduction of the CD to today. The increase in loudness is accompanied by a decrease in dynamic range.