Loudness war

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The phrase loudness war (or loudness race) refers to the music industry's tendency to record music at progressively higher and higher levels, to create CDs that sound perceptibly as loud as possible or "louder" than CDs from competing artists or recording labels. While the overall maximum amplitude of a CD cannot be increased, reducing the dynamic range of the signal using audio compression will cause the human ear-brain mechanism to perceive the overall signal as being louder, when in fact merely the difference between loud and quiet portions of audio has been reduced.

1 Introduction
2 Negative Impact of Audio Volume Compression on Modern Rock Recordings
3 Effects
4 History
5 Interpretations
6 Remasters
7 Other Formats
8 Possible Solutions
9 Popular Examples
10 References
11 See also
12 External links

[edit] Introduction

Ever since the introduction of the CD, record labels have been progressively increasing the loudness of their CD releases. The justification for this is the assumption by CD companies that a louder sounding CD will also sound louder on the radio and thus increase their sales. But this assumption is false, as radio stations regularly employ sound leveling devices to prevent overmodulation (distortion) of their programming.

[edit] Negative Impact of Audio Volume Compression on Modern Rock Recordings

The technique being used by CD companies to increase the average loudness of their music is called audio volume compression. Satellite radio also uses this same technique. Volume compression is where loud passages in the music are reduced in volume while soft passages are made louder. This results is music that has very little variation in sound level. Less variation permits the CD sound engineers to raise the overall loudness level so that the signal peaks are very close to (or even exceeding) the clipping level.

While audio volume compression is sometimes beneficial, as when listening to music in noisy environments, such as a car with the windows open, it is nonetheless distortion. The fact that the modern CD is capable of 90dB dynamic range, while an LP record typically provides only about 40dB is lost on those who manufacture modern rock recordings. The sad fact is that the vast majority of modern CDs have a dynamic range that is less than that of an 8 track tape!

Add to this the practice of not allowing a return on a CD which has been opened and the consumer is now placed in a position of accepting poor quality recordings. Artists also tend to prefer that their mastered CDs match the dynamic range of the music as recorded. Bob Dylan has complained publicly (in a Rolling Stone magazine interview) about the poor quality sound of modern CDs. Classic rock recordings, of the 1960's and 70's, after they have been "remastered" often sound harsh and very different from the natural, wide range LP record sound that potential customers had expected.

As a general rule, classical music recording tend to be compression free (full dynamic range).

The practice of deliberately modifying the dynamic range of recordings to make them sound louder has been condemned by several recording industry professionals including Grammy Award-winning mastering engineer Doug Sax^[1], noted recording/mastering engineer Barry Diament^[2], and many others.^[3]^[4]. It is also considered unnecessary by its opponents (which also include audiophiles and hi-fi enthusiasts), who believe that the same effect can be achieved simply by turning up the volume on their playback equipment. Moreover, if a CD is broadcast by a radio station, the station will have its own equipment that reduces the dynamic range of material it broadcasts to far more closely matching levels of absolute amplitude, regardless of the original recording's loudness.^[5]^[6]

Opponents have also called for immediate changes in the music industry regarding loudness. Bands have been petitioned to re-release some CDs with less distortion.^[7] It has even been said that recording engineers who knowingly push their recording equipment past clipping should be blacklisted and not allowed to "victimize artists or music lovers."^[8] Boycotting of such recordings has been suggested, although record labels may be likely to attribute loss in sales to piracy, alternative forms of distribution, or simply as a by-product of changing public interests.

[edit] Effects

Unclipped waveform before amplification

After amplification, the waveform has been distorted, or clipped

The practice of increasing a CD's loudness to be louder than competing CDs often results in a form of distortion known as clipping.^[9] Digital media cannot output signals higher than 0 dB, so whenever the peak of a signal is pushed past 0db, it results in the wave form becoming "clipped". When this occurs, it can sometimes produce an audible "click". However, very often certain sounds like drum hits will reach their peak for only a very short time, and if that peak is much louder than the rest of the signal, this allows an engineer to amplify the recording simply by increasing the volume. The peaks of the drum hits will be clipped, but it will not be noticeable to the casual listener. However, if clipping occurs too much in a recording, or if certain signals are noticeably clipped, it can make the recording sound distorted, making it harsh and fatiguing to listen to. How much is too much is a matter of taste, but most pop CDs, and many classical and jazz CDs have some amount of digital clipping.

In other cases, compression or limiting is used. While the resulting distortion is lessened from the final product this way, it has the side effect of significantly reducing transient response (most often heard as lessened drum impact), and when taken to severe levels, can reduce the natural dynamic ranges of other instruments within the recording. Loudness increasing techniques, however, do not always affect macrodynamics (the difference in volume between sections of a song). For example, loudness-based compressors (such as limiters) will only affect the signal in a "local" manner. Multi-band compression is commonly used to make a mix more uniform and easier to balance, more compatible with low-end equipment, or to achieve a certain "sound" or artistic effect. Slow-acting, broadcast-style compression, on the other hand, will be applied to the music to make the the volume in different song sections more uniform. This can make the recording more suitable for background listening or noisy environments, but can also reduce the dynamic expressiveness of the song as a whole.

[edit] History

(Note: Some of these examples are explained using RMS (Root Mean Square) power values. In reference to CD audio, these values are based on the calculation of the average of CD audio sample values with digital full scale used as a reference. It is a common way to determine the absolute loudness of a recording, though discrepancies in musical arrangements can cause inconsistencies in regards to aforementioned value versus perceived loudness.)

The practice of focusing on loudness in mastering can be traced back to the introduction of the compact disc itself, but has also been said to exist when vinyl was the primary released recording medium. For example, many Motown records pushed the limits of how loud records could be made, and "was notorious for cutting some of the hottest 45s in the industry."^[10] However, because of the limitations of the vinyl format, loudness and compression on a released recording were restricted in order to make the physical medium playable — restrictions which do not exist on digital media such as CDs — and as a result, increasing loudness levels never reached the significance that they have in the CD era. For example, extraordinarily high recording levels like those showcased by Japanese noise artist Merzbow, which are significantly louder than even today's norm, would be impossible on vinyl.

The stages of CD loudness increase are often split over the three decades of the medium's existence. Since CDs were not the primary medium for popular music until the tail end of the 1980s, there was little motivation for competitive loudness practices then. CD players were also very expensive and thus commonly exclusive to high-end systems that benefited less from higher recording levels during this period. In addition, for the first four or five years of the CD, there was absolutely no way for a recording to be compressed in the digital domain, as signal processing in the digital domain did not exist for mastering engineers.

As a result, the two common practices of mastering CDs involved either matching the highest peak of a recording at, or close to, digital full scale, or referencing digital levels along the lines of more familiar analog VU meters. When using VU meters, a certain point (usually −6 dB, or 50% of the disc's amplitude on a linear scale) was used in the same way as the saturation point (signified as 0db) of analog recording, with several dB of the CDs recording level reserved for amplitude exceeding the saturation point (often referred to as the "red zone", signified by a red bar in the meter display), because digital media cannot exceed 0db. The RMS level of the average rock song during most of the decade was around −18 dB.

At the turn of the decade CDs louder than this level began to surface, and CD volumes became more and more likely to exceed the digital limit as long as such amplification would not involve clipping more than approximately 2-4 digital samples, resulting in recordings where the peaks on an average rock or beat-heavy pop CD hovered near (usually in the range of -3dB) 0db but only occasionally reached it. Guns N' Roses's 1987 album Appetite for Destruction is an early example of this, with RMS levels averaging −15 dB for all the tracks.

In the early 1990s, some mastering engineers decided to take this a step further, and treat the CDs levels exactly as they would the levels of an analog tape and equate digital full scale with the analog saturation point, with the recording just loud enough so that each (or almost every) beat would peak at or over 0db. Though there were some early cases (such as Metallica's self-titled "Black Album" in 1991), albums mastered in this fashion generally did not appear until 1992. Alice in Chains's Dirt, Rage Against the Machine's self-titled debut and Faith No More's Angel Dust are some examples from this year. The loudness of CDs during this period varied massively depending on the philosophies of the engineer and others involved in the mastering process. 1994 was the year in which this style of "hot" mastering became commonplace, though exceptions, such as the album Superunknown by Soundgarden from the same year, still existed. The most common loudness for a rock CD in terms of RMS power was around −12 dB. Overall, most rock and pop CDs released in the 1990s followed this method to a certain extent.

The concept of making CDs "hotter" began to appeal to people within the industry, due in part to how noticeably louder CDs had become, and also in part to the notion that customers preferred louder CDs. Engineers, musicians and labels each developed their own ideas of how CDs could be made louder. While the increase in CD loudness was gradual throughout the 1990s, some opted to push the format to the limit, such as on Oasis' widely popular album (What's the Story) Morning Glory?, which reached −8 dB on many of its tracks — a rare occurrence, especially in the year it was released (1995). In 1997, Iggy Pop assisted in the remix and remaster of the 1973 album Raw Power by his former band The Stooges, creating an album which, to this day, is arguably the loudest rock CD ever recorded. It has an RMS of -4 dB in places, which is rare even by today's standards.

The standards of loudness would reach its limit in the 2000s. −10 dB has been the standard for the past several years, but this is often pushed to −9 dB, and occasionally higher. Quieter exceptions to today's standards are rare.

[edit] Interpretations

Views regarding the impact of the loudness war are heavily subjective. Proponents of louder CDs claim that consumers prefer louder CDs and that they are better for most busy listening environments. Many hold the opinion that only a handful of albums (such as the Red Hot Chili Peppers 1999 release Californication, a CD with such excessive amounts of high-frequency digital clipping that casual listeners as well as audio enthusiasts have made complaints^{[citation needed]}) are examples worth considering, while other, more fanatical types believe any CD where digital full scale is frequently utilized (or when mastering processes are used solely to prevent such when attempting the same volume) should be considered unacceptable.^[11]^[12] Likewise, many listeners do not notice the effects, some consider it a minor annoyance, and others find themselves completely unable to listen to albums mastered in a loudness-based fashion.^[13]

Many mastering engineers claim they are forced to record CDs louder than they would prefer, often blaming a variety of parties.^{[citation needed]} The most commonly accused is the executives at the recording label, who are said to demand CDs of "competitive" playback levels and disallow the release of any disc that is not up to their ideal of CD loudness, and threaten to give the job to a different engineer, or even blacklist the engineer if they refuse to comply. Some accuse the artists and/or producers of being ignorant or apathetic of proper recording practices and requesting their CDs be made as loud as possible, while others blame mixing engineers with similar mindsets or lack of experience for compressing or distorting the mix prior to sending it off for mastering.^{[citation needed]}

[edit] Remasters

One Of Us, 1981 release

One Of Us, 2005 remaster

Recently many classic albums have been re-released in remastered form. In its most basic form, the current remastering practice is to boost the bass and treble frequencies (which does actually create a perceived improvement - see the Fletcher-Munson diagram above) and to boost the average level with the aid of compression.

The two screenshots here, of ABBA's One Of Us, demonstrate the effect.

The first image is taken from the original 1981 Polydor CD release, where there is no clipping or distortion, and a good deal of headroom.

The second image is taken from the 2005 remaster (part of the Complete Studio Recordings box set). There is a heavy amount of compression, and many of the dynamics and "snap" of the original track have been lost as a result.

The Popular Examples section contains several other remastered albums that have been remastered in this fashion.

[edit] Other Formats

At present the loudness war appears to only affect audio CDs and consequently any MP3s ripped from them. Recent recordings released on vinyl, though nowadays hard to obtain, do not undergo the same kind of loudness-based mastering. This is partly due to technical limitations of the format and partly due to vinyl now being a niche market product favoured by a small number of hi-fi enthusiasts — similar to the CD's role in the mid-1980s.

New formats like DVD-Audio and SACD have also not been affected at this time. Indeed, DVD-Audio may well be partially immune to the problem, as virtually all DVD-Audio releases feature a Dolby Digital (AC-3) soundtrack. AC-3 has a standard and defined playback reference level, along with a dynamic range control (DRC) facility. This functionality is built into all DVD players, home theatre amplifiers, and decoders, and allows dynamic range to be reduced for low volume listening.

High-end systems with DVD-Audio playback will use the linear PCM tracks. On all present DVD-A releases, however, these are not subject to loudness-based mastering.

[edit] Possible Solutions

Many digital music formats now have the ability to analyse the volume of a given piece of music and either store this as metadata to allow the player to compensate on playback, or to losslessly alter the music file to match the volume to a standard level.

The iTunes software has a feature called Sound Check, which calculates the perceived loudness of audio tracks as they are imported into the music library, and adjusts accordingly on playback. Windows Media Player has a similar feature (called simply Volume Leveling), and other formats such as FLAC calculate the perceived loudness as part of the encoding process, allowing the player to adjust the volume on a per-track basis.

One Of Us, 1981 release with Replay Gain

One Of Us, 2005 remaster with Replay Gain

In 2001 Replay Gain was created as a new proposed standard for MP3 format. The OGG format has a similar facility called VorbisGain. The Replay Gain idea has been implemented for example in a free utility called MP3Gain. This software calculates the perceived loudness of an individual track, then adjusts the scale factor of each frame of the MP3 file to losslessly alter the playback level. When gain is adjusted like this, "hot" compressed tracks can often sound slightly quieter than older less compressed material. The most effective demonstration of this can be performed by comparing an original CD release to a remaster. See examples.

It should be noted however that volume levelling, Replay Gain, VorbisGain etc. can only reduce the volume of "loudness mastered" music so it does not blow the listener out of their seat when that album is selected. It cannot restore dynamics or undo clipping, so the ultimate solution may lie with a new digital media entirely.

The new DualDisc format is a double-sided disc with CD audio on one side (usually mastered for maximum loudness) and DVD-Audio on the other. This offers a compromise: the CD audio side can be played in the car or transferred to an iPod or similar device and thereby gain some of the perceived benefits of compression, and the DVD-Audio side can be played at home to allow listeners to experience the full dynamic range of the recording.

HDCD (High Definition Compatible Digital) is a technology that uses dynamic range compression when mastering a CD. When played back on a normal CD player the sound will be compressed and "loud". When played back on a CD player equipped with HDCD decoding, a dynamic range expander is brought into play, reversing the compression applied at mastering. Were it to be more widely adopted, HDCD would allow CDs to be made louder for the average consumer while maintaining dynamic range when played on an HDCD player. Unfortunately, however, relatively few CD players have HDCD decoding. There are also several licensing restrictions when using the technology; for example, the decoded signal may not be made available via a digital output.

[edit] Popular Examples

"One Little Victory" (file info) — play in browser (beta)
- "One Little Victory" from Rush's Vapor Trails.
- Problems listening to the file? See media help.

"Exo-politics by Muse, Some of the many clipping parts

Here are some of the more commonly touted examples of loudness-based mastering. These CDs represent some of the most extreme examples of loudness increase via compression and distortion in popular music: