Audio normalization is the application of a constant amount of gain to an audio recording to bring the amplitude to a target level (the norm). Because the same amount of gain is applied across the entire recording, the signal-to-noise ratio and relative dynamics are unchanged. Normalization is one of the functions commonly provided by a digital audio workstation.
Two principal types of audio normalization exist. Peak normalization adjusts the recording based on the highest signal level present in the recording. Loudness normalization adjusts the recording based on perceived loudness.
Normalization differs from dynamic range compression, which applies varying levels of gain over a recording to fit the level within a minimum and maximum range. Normalization adjusts the gain by a constant value across the entire recording.
https://en.wikipedia.org/wiki/Audio_normalization
The loudness war (or loudness race) is a trend of increasing audio levels in recorded music, which reduces audio fidelity and—according to many critics—listener enjoyment. Increasing loudness was first reported as early as the 1940s, with respect to mastering practices for 7-inch singles.[1] The maximum peak level of analog recordings such as these is limited by varying specifications of electronic equipment along the chain from source to listener, including vinyl and Compact Cassette players. The issue garnered renewed attention starting in the 1990s with the introduction of digital signal processing capable of producing further loudness increases.
With the advent of the compact disc (CD), music is encoded to a digital format with a clearly defined maximum peak amplitude. Once the maximum amplitude of a CD is reached, loudness can be increased still further through signal processing techniques such as dynamic range compression and equalization. Engineers can apply an increasingly high ratio of compression to a recording until it more frequently peaks at the maximum amplitude. In extreme cases, efforts to increase loudness can result in clipping and other audible distortion.[2] Modern recordings that use extreme dynamic range compression and other measures to increase loudness therefore can sacrifice sound quality to loudness. The competitive escalation of loudness has led music fans and members of the musical press to refer to the affected albums as "victims of the loudness war".
History[edit]
The practice of focusing on loudness in audio mastering can be traced back to the introduction of the compact disc,[3] but also existed to some extent when the vinyl phonograph record was the primary released recording medium and when 7-inch singles were played on jukeboxmachines in clubs and bars. The so-called wall of sound (not to be confused with the Phil Spector Wall of Sound) formula preceded the loudness war, but achieved its goal using a variety of techniques, such as instrument doubling and reverberation, as well as compression.[4]
Jukeboxes became popular in the 1940s and were often set to a predetermined level by the owner, so any record that was mastered louder than the others would stand out. Similarly, starting in the 1950s, producers would request louder 7-inch singles so that songs would stand out when auditioned by program directors for radio stations.[1] In particular, many Motown records pushed the limits of how loud records could be made; according to one of their engineers, they were "notorious for cutting some of the hottest 45s in the industry."[5] In the 1960s and 1970s, compilation albums of hits by multiple different artists became popular, and if artists and producers found their song was quieter than others on the compilation, they would insist that their song be remastered to be competitive.
Radio broadcasting[edit]
When music is broadcast over radio, the station applies its own signal processing, further reducing the dynamic range of the material to closely match levels of absolute amplitude, regardless of the original recording's loudness.[38]
Competition for listeners between radio stations has contributed to a loudness war in radio broadcasting.[39] Loudness jumps between television broadcast channels and between programmes within the same channel, and between programs and intervening adverts are a frequent source of audience complaints.[40] The European Broadcasting Union has addressed this issue in the EBU PLOUD Group with publication of the EBU R 128 recommendation. In the U.S., legislators passed the CALM act, which led to enforcement of the formerly voluntary ATSC A/85 standard for loudness management.
https://en.wikipedia.org/wiki/Loudness_war
See also[edit]
Notes[edit]
- ^ Up to 2 or 4 consecutive full-scale samples was considered acceptable.
- ^ Usually in the range of −3 dB.
- ^ Look-ahead is a window of time in which the processor analyzes the audio amplitude in advance and predicts the amount of gain reduction needed to meet the requested output level (0 dBFS); this permits the limiter to react to incoming transients avoiding clipping. Since an audio buffer is needed to achieve this, look-ahead is only possible in the digital domain and introduces a small amount of latency to the output signal.
- ^ The vinyl version of this album does not have the same quality issues.
- ^ Won Grammy Award in 2006 for Best Engineered Album, Non-Classical
- ^ The 2015 remaster of this compilation does not have the same quality issues.
- ^ The Guitar Hero version of this album does not have the same quality issues.
- Van Buskirk, Eliot (16 September 2008). "Analysis: Metallica's Death Magnetic Sounds Better in Guitar Hero". Wired. Retrieved 17 September 2008.
- ^ Michaels, Sean (1 October 2008). "Death Magnetic 'loudness war' rages on". The Guardian. London. Retrieved 17 October 2008.
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