question: If dynamic range compression on songs is well known to lessen the quality if the music, then why does it continue to be done?
comment: I imagine a combination of many people don't like silence, and automation. If I'm listening to music and the artist decides that this next bit should be 2x as loud, im going to be annoyed as I set the volume to the level I, the listener, want. If I really want to sit and enjoy the music as intended that's one thing, but its much more common I just want it playing in the background where I would rather it all be about the same loudness In summary people don't want the music to suddenly get really loud
passages: Compression is often used in music production to make performances more consistent in dynamic range so that they "sit" in the mix of other instruments better and maintain consistent attention from the listener. Vocal performances in rock music or pop music are usually compressed to make them stand out from the surrounding instruments and add clarity.
   Record companies, mixing engineers and mastering engineers have been gradually increasing the overall volume of commercial albums. The greater loudness is achieved by using higher degrees of compression and limiting during mixing and mastering; compression algorithms have been engineered specifically to accomplish the task of maximizing audio level in the digital stream. Hard limiting or clipping can result, affecting the tone and timbre of the music. The effort to increase loudness has been referred to as the loudness war.
  
  Section::::Uses.:Other uses.
   The excessive use of dynamic range compression has been bemoaned by critics as part of the "loudness war". In August 2006, Bob Dylan criticized modern recording techniques, saying that modern records "have sound all over them" and that they sound like "static". Those responding to Dylan's comments seemed to assume that he was referring to the trend of increasingly compressed music.
  
  The use of the Auto-Tune audio processor for pitch correction has become pervasive in pop music since late 1998, and has elicited criticism.
   But loudness jumps are not limited to inter-channel differences; they also exist between programme material within the same channel. Loudness differences are a frequent source of audience complaints, especially TV commercials and promos that seem too loud. Complicating this is that many broadcasters use (quasi-)peak meters and peak-levelling. Unfortunately the peak level reading does not correlate well with the perceived loudness. It basically should only be used to prevent overmodulation.
   In many compressors the attack and release times are adjustable by the user. Some compressors, however, have the attack and release times determined by the circuit design and these cannot be adjusted by the user. Sometimes the attack and release times are "automatic" or "program dependent", meaning that the behavior may change dependent on the input signal.
  
  Section::::Controls and features.:Soft and hard knees.
   Compression can also be used on instrument sounds to create effects not primarily focused on boosting loudness. For instance, drum and cymbal sounds tend to decay quickly, but a compressor can make the sound appear to have a more sustained tail. Guitar sounds are often compressed to produce a fuller, more sustained sound.
  
  Most devices capable of compressing audio dynamics can also be used to reduce the volume of one audio source when another audio source reaches a certain level; this is called side-chaining.
   Some applications use a compressor to reduce the dynamic range of a signal for transmission, expanding it afterward. This reduces the effects of a channel with limited dynamic range. See "Companding".
  
  Bass amplifiers and keyboard amplifiers often include compression circuitry to prevent sudden high-wattage peaks that could damage the speakers. Electric bass players often use compression effects, either effects units available in pedal, rackmount units, or built-in devices in bass amps, to even out the sound levels of their basslines.
   Electronically reproduced audio and video is often processed to fit the original material with a wide dynamic range into a narrower recorded dynamic range that can more easily be stored and reproduced; this processing is called dynamic range compression.
  
  Section::::Human perception.
   The highest ratio of ∞:1 is often known as "limiting". It is commonly achieved using a ratio of 60:1, and effectively denotes that any signal above the threshold is brought down to the threshold level once the "attack" time has expired.
  
  Section::::Controls and features.:Attack and release.
   Compressors are also used for hearing protection in some electronic "active sound protection" earmuffs and earplugs, to let sounds at ordinary volumes be heard normally while attenuating louder sounds, possibly also amplifying softer sounds. This allows, for example, shooters wearing hearing protection at a shooting range to converse normally, while sharply attenuating the much louder sounds of the gunshots, and similarly for musicians to hear quiet music but be protected from loud noises such as drums or cymbal crashes.
   Section::::Software audio players.
  
  Some software audio players support plugins that implement compression. These can increase perceived volume of audio tracks, or even out the volume of highly-variable music (such as classical music, or a playlist that spans multiple music types). This improves listenability of audio played through poor-quality speakers, or when played in noisy environments (such as in a car or during a party). Such software may also be used in micro-broadcasting or home-based audio mastering.
  
  Section::::Objective influence on the signal.
   The tested limiters had the following influence on the signal:
  
  BULLET::::- increase of RMS power,
  
  BULLET::::- increase of EBU3341 loudness,
  
  BULLET::::- decrease of crest factor,
  
  BULLET::::- decrease of EBU3342 LRA, but only for high amounts of limiting,
  
  BULLET::::- increase of clipped sample density.
  
  In other words, limiters increase both physical and perceptual levels, increase the density of clipped samples, decrease the crest factor and decrease macro-dynamics (LRA) given that the amount of limiting is substantial.
  
  Section::::Objective influence on the signal.:Compressors.
   Section::::Parallel compression.
   Section::::Serial compression.
   Because a downward compressor only reduces the level of the signal, the ability to add a fixed amount of "make-up gain" at the output is usually provided so that an optimum output level is produced.
  
  Section::::Controls and features.:Look-ahead.
   As was alluded to above, the use of compressors to boost perceived volume is a favorite trick of broadcasters who want their station to sound "louder" at the same volume than comparable stations on the dial. The effect is to make the more heavily compressed station "jump out" at the listener at a given volume setting.
   Post-production houses, content delivery networks and studios use adaptive bit rate technology in order to provide consumers with higher quality video using less manpower and fewer resources. The creation of multiple video outputs, particularly for adaptive bit rate streaming, adds great value to consumers. If the technology is working properly, the end user or consumer's content should play back without interruption and potentially go unnoticed. Media companies have been actively using adaptive bit rate technology for many years now and it has essentially become standard practice for high-end streaming providers; permitting little buffering when streaming high-resolution feeds (begins with low-resolution and climbs).
   Another control a compressor might offer is hard knee or soft knee selection. This controls whether the bend in the response curve between below threshold and above threshold is abrupt (hard) or gradual (soft). A soft knee slowly increases the compression ratio as the level increases and eventually reaches the compression ratio set by the user. A soft knee reduces the potentially audible transition from uncompressed to compressed, and is especially applicable for higher ratio settings where the changeover at the threshold would be more noticeable.
  
  Section::::Controls and features.:Peak vs RMS sensing.
   One technique is to insert the compressor in a parallel signal path. This is known as parallel compression, a form of upward compression that facilitates dynamic control without significant audible side effects, if the ratio is relatively low and the compressor's sound is relatively neutral. On the other hand, a high compression ratio with significant audible artifacts can be chosen in one of the two parallel signal paths—this is used by some concert mixers and recording engineers as an artistic effect called "New York compression" or "Motown compression". Combining a linear signal with a compressor and then reducing the output gain of the compression chain results in low-level detail enhancement without any peak reduction (since the compressor significantly adds to the combined gain at low levels only). This is often beneficial when compressing transient content, since it maintains high-level dynamic liveliness, despite reducing the overall dynamic range.
   In music, "dynamic range" is the difference between the quietest and loudest volume of an instrument, part or piece of music. In modern recording, this range is often limited through dynamic range compression, which allows for louder volume, but can make the recording sound less exciting or live.
   To help audio engineers understand what Loudness Range their material consists of (e.g. to check if some compression may be needed to fit it into the channel of a specific delivery platform), the EBU also introduced the Loudness Range Descriptor.
  
  Section::::Uses.:Marketing.
   In March 2010, mastering engineer Ian Shepherd organised the first Dynamic Range Day, a day of online activity intended to raise awareness of the issue and promote the idea that "Dynamic music sounds better". The day was a success and its follow-ups in the following years have built on this, gaining industry support from companies like SSL, Bowers & Wilkins, TC Electronic and Shure as well as engineers like Bob Ludwig, Guy Massey and Steve Lillywhite. Shepherd cites research showing there is no connection between sales and loudness, and that people prefer more dynamic music. He also argues that file-based loudness normalization will eventually render the war irrelevant.
   The master recording process, using current 24-bit techniques, offers around 99 dB of "true" dynamic range (based on the "ITU-R 468 noise weighting" standard); identical to the dynamic range of a good studio microphone, though very few recordings will use just one microphone, and so the noise on most recordings is likely to be the sum of several microphones after mixing, and probably at least 6 dB worse than shown.
  
  Section::::See also.
  
  BULLET::::- Audio system measurements
  
  BULLET::::- Noise measurement
  
  BULLET::::- Weighting filter
  
  BULLET::::- Equal-loudness contour
  
  BULLET::::- Fletcher-Munson curves
  
  Section::::External links.
  
  BULLET::::- EBU Recommendation R68-2000
   Multiband compressors can act differently on different frequency bands. The advantage of multiband compression over full-bandwidth compression is that unneeded audible gain changes or "pumping" in other frequency bands is not caused by changing signal levels in a single frequency band.
   The incorporation of (switchable) level compression in domestic music systems and car in-car systems would allow higher quality on systems capable of wide dynamic range and in situations that allowed realistic reproduction. Such compression systems have been suggested and tried from time to time, but are not in widespread use — a 'chicken and egg' problem since producers feel they must make programmes and recordings that sound good in car with high ambient noise or on cheap low-power music systems. In the UK, some DAB receivers do incorporate a menu setting for automatic loudness compensation which adds extra gain on BBC Radio 3 and BBC Radio 4, to allow for the fact that these programmes adopt lower levels than, for example, the pop station Radio 1. Some television receivers also have a menu setting for loudness normalisation, aimed at helping to reduce excessive loudness on advertisements. However, there is no common agreement to reduce compression and limiting and leave these tasks to the receiver.
  