Bronze-level article

Audio woo

From RationalWiki
Jump to: navigation, search
A classic example of the species.
Style over substance
Icon pseudoscience.svg
Popular pseudosciences
Random examples

Audio woo consists of various vague and unsupported claims for devices or methods for getting better sound quality from systems that reproduce recorded music. Such claims are made by manufacturers, hobbyists, and writers in the field.

In at least two senses of the word, audio woo is not to be considered sound science.[note 1]

The quest for perfect sound[edit]

An audiophile is someone dedicated to producing the highest possible fidelity in the playback of music. While this is a reasonable goal, much of the industry that caters to them sells extremely high-priced equipment that claims to improve sound through highly dubious mechanisms and/or badly misunderstood real science. Most double-blind studies have shown that there is no difference in detectable sound quality for most of the equipment sold,[1] and some of it is actually inferior in quality to less expensive products. Many of the products use appeals to magical thinking and pseudoscience to explain their mechanisms. While some of them do indeed provide a small, subtle improvement in sound quality, the unscientific claims by the manufacturers as to why they might sound better lead to a subculture of people who are utterly deluded about how to get the best sound from an audio system.

These particular audiophiles are widely known in the electronics trade as people who put subjective sound experience above objective measurement as the primary way to judge sound reproduction; as a result, many refuse to admit that their beloved "warmer" sound[note 2] is actually a form of distortion. Double-blind testing is shunned, as in many other pseudoscientific pursuits, since it removes the power of suggestion (by brand name, equipment appearance, or price) from the testing room and has a frustrating inability to confirm their prior prejudices. At the extreme end of this particular brand of audiophiles are the "tweakers" whose obsession leads to belief in some of the more bizarre claims (read: scams) of the subjective audiophile industry.

There exists an inverted class of audiophiles who claim that the sound of vinyl, i.e. reproducing music by scraping needles across pieces of plastic, is superior to the sound of compact discs or other digital music despite the objectively improved distortion, dynamic range, and repeatability of digital recordings.

An anonymous wag, in the tradition of The Devil's Dictionary by Ambrose Bierce, once defined such an audiophile as someone who listens to the stereo, not the music. Indeed, there are even people who collect and assemble such systems with no goal of even listening to music!

The science[edit]

There are certainly valid ways to increase sound quality; the electrical and acoustic principles at work here are well understood, and there are real engineers and scientists who work in this field. Noise can be reduced by improved filtering or gain staging; frequency response and distortion improved through the use of negative feedback in amplifiers; and so on. However, the major stumbling blocks are the recording quality and later compression and manipulation of the original signal itself, the cost of better parts, and just how much any change actually increases quality. Once a certain point is reached, any further increases become harder to detect. The point of diminishing returns is rapidly reached.

Psychological explanations[edit]

Explanations for why manufacturers, audiophiles and the "tweakers" perpetuate the myths of the subjective audio crowd are varied but one simple explanation is cognitive dissonance: having just spent thousands of dollars on something that does very little or nothing, it is easier to adjust one's thinking to "Wow! spending hundreds of dollars on little ceramic insulators that keep my speaker wires off the floor has opened up the sound stage and improved the distinction between the violin parts!", than it is to admit the fundamental realities that say "I can't believe how dumb I have been" and "my wife will kill me!". The brilliant thing about this is that it works in proportionality to how dumb the purchase was (and how expensive it was) — so the more ridiculous the tweak, the more believing the purchaser will be.[2] This brings into question the review policy of subjective audio reviewers such as Positive Feedback, where reviewers often own the equipment they are reviewing.[3]

Explanations can also include the concepts of buyer's remorse, which can actually fuel the effect in a negative feedback loop.

The tube thing[edit]

Subjectivist audiophiles often express a preference for tube-based amplifiers due to their perception of a warmer, "natural" sound, to the point where scam artists have sold products claiming to make transistors function like tubes.

As a general rule, tubes for mainstream audio folks are not inherently bad (though perhaps a bit high-maintenance). However, while tubes are very popular in guitar and other instrument amplifiers due to their unique sound,[note 3] they are unnecessary in playback amplifiers. Much like with Vinyl, they add a coloration to sound that is deemed pleasurable (yet not more accurate — quite the opposite, in fact). Skeptics of tube amplifiers argue that audiophiles prefer the inherent distortion provided in the antiquated technology while paradoxically claiming the sound is purer and more perfect.[4]

The tube thing can get truly stupid. A vacuum tube computer sound card, anyone?

The vinyl thing[edit]

A great many audiophiles hold up vinyl records as being the be-all and end-all of sound reproduction. Vinyl, though largely a niche format since the CD improved portability and instant gratification, does have a few uses, particularly archival.[note 4] In addition, the limitations of vinyl records and alternate mastering process spare them from the "Loudness Wars" — the constant race among record producers to use dynamic range compression to make songs as loud as possible, often distorting the sound in the process.

However, vinyl records inevitably suffer from wear during playback, especially with use of a stylus rather than a laser or a scanner — so unless you're willing to shell out multiple thousands of dollars for a laser turntable, your records will eventually degrade.[note 5][5][6] Dynamic range is also limited — depending on bandwidth, sample rate, and storage capacity, a digital format can equal the performance of an analog medium of equivalent bandwidth.[note 6] Hypothetically, even if vinyl records were superior for being analog in nature, many songs are exclusively recorded or mixed digitally, rendering newer analog masters moot.

All that being said, the difference between vinyl and digital "is just not that important a part of the overall system."[7] Speakers, microphones, amplifiers, mastering… all of these considerations will far outweigh the difference the format makes.

In a nutshell[edit]

The bi-wiring thing[edit]

It don't make no sense.
One of the most pervasive audio woos is the notion of bi-wiring speakers. This is where you buy twice as much cable so that the woofers and tweeters can be fed (from the same amplifier!) separately using an extra set of connections on the speakers. This allegedly prevents "crosstalk interference" or something but essentially does nothing except make you spend more money. Unless there are completely separate amplifiers used to power the high and low ranges, the effect is the same as simply using a double thickness wire as nothing changes electronically (or audio-magically) to the circuit whatsoever due to the superimposition principle.[8] Unfortunately, few hi-fi speaker manufacturers dare to release speakers without bi-wiring ports as the all-prevailing nature of the myth would mean they simply would not be able to sell them. To quote an honest manufacturer:
Will it sound any different if you biwire? Some users think it does, but I've never heard any differences, nor have any of our laboratory measurements or scientifically controlled double blind listening tests ever demonstrated there are audible differences. Axiom includes the extra terminals as a nod to those enthusiasts who believe that biwiring results in audible benefits and for the bi-ampers.[9]

Note that the bi-wiring inputs provided are essential for those who intend to bi-amp their speakers. However, as many of these speakers contain passive crossovers, it would seem that they defeat the purpose of bi-amping, the ultimate benefits of which are derived precisely from eliminating the passive crossovers.[10]

The digital thing[edit]

This is not how digital audio works. The samples are interpolated smoothly, not using stairsteps.

Three words: bits is bits.

Okay, here's more: digital data streams don't work much like analog streams, at least from the user's point of view.[note 7] At least from the point of view of content, digital signals don't degrade gracefully; they drop hard and lose big whacks of information as the decoding hardware on the client end gets confused. When an analog signal is weakened, you get signal attenuation and snow; when a digital signal degrades, you get dropouts, stutters, and (on video hardware) blocky and smearing images.[note 8]

The first thing you need to know is the basics of how analog signals are converted to digital, starting with the Nyquist-Shannon sampling theorem[11] and how it relates to signal encoding. To understand what a digital signal looks like, imagine a continuous wave signal of N hertz; in order to represent this frequency at all, the sample rate has to be at least 2N.[note 9] In digital signal processing, each sample is now reduced to a digital number, usually a scalar value, and read out as a stream of bits to the destination device.[note 10] This approach is more or less the basis of the usual representation of uncompressed audio dataWikipedia's W.svg on a CD or in a .wav file, and the data can be compressed, transformed, or transmitted like any other form of digital data.[note 11] As a result, though any digital signal is going to be an approximation of the analog signal it represents, its precision can be as narrow as you need it to be, within the limits of the sampling device. On a reliable link, an uncompressed[note 12] signal has zero generation loss between source and destination.

The important thing to know is that when discussing ways to "improve" a digital signal, the analog carrier is a low-level[note 13] issue that is largely transparent to the parts of the system that actually handle the data. If an analog carrier signal is corrupted on an analog device, the result may be scrambled, attenuated, or otherwise damaged, but the signal will still get through; however, if a digital signal is disrupted, the receiving hardware won't be able to make sense of the analog signal and will therefore decode either a wrong value or no value at all; barring some seriously incompetent circuit board design, the input of the analog stage has no influence on the input to the digital stage. Subtle signal changes claimed by people who spend extra cash on pricey HDMI, TOSlink, and USB cables simply can't be caused by changing cables, since it implies that the cable is actually physically changing the data it passes through.[note 14] Fundamentally, then, what's going on with digital audiophoolery is a failure to understand the difference between analog and digital communication. You may as well expect your software to run faster or your cheezy fanfics to read like Stephen King or Toni Morrison.

Some cables with gold plated connectors are sold at a higher price than the regular cables. Gold plated contacts reduce the contact resistance if both touching contacts are gold plated. This makes gold plated connectors somewhat justified for analog signals where sometimes resistance does actually matter. Especially in case of balanced analog signaling where impedance matching is important (something that is not always done by manufacturers of the equipment). But in the case of digital transmission resistance can not affect the data unless it's so high that it distorts the signal in such a way that reliable reception becomes impossible. A bit can only encode two different values (0 or 1) so either it arrives correctly or it doesn't.[note 15] And in case of frequent random data corruption you would clearly notice the distortions anyway. However this does not prevent some manufacturers from selling cables with gold plated connectors for USB, HDMI, (optical!!!) TOSLINK, etc. Not to mention that modern standards like USB include automated error detection and correction.[note 16]

There are cases where cable quality makes a difference; for example, cheap straight-wire Cat3 Ethernet cable is no longer widely available, since it results in excessive crosstalk at high speeds resulting in massive packet loss; the twisted-pair wires favored for most telecom and data applications work in a way distantly related to shielded coax to prevent that. But it is still the case that from the digital standpoint, the result of a low-quality cable is not data corruption but outright data loss. And fiber optic isn't subject to this to begin with, as light transmission physics are rather different from the radio band signals used by electrical connections. This also applies to storage media -- a CD could have a scratch that affects tracking, optical imperfections that screw with the laser, or physical damage to the recording layer, but in either case you won't hear a degraded signal because you won't hear anything at all.[note 17]

Note that when dealing with compressed AV streams, the rules do change; most audio compression formats (MP3, AAC, Ogg Vorbis, etc) and virtually all currently widely used video formats (MPEG-x, DV, AVCHD, etc) throw out large amounts of data during the compression process in order to bring the file size down to something manageable. This usually won't be a problem for the majority of listeners/viewers, though sharp eyes and ears can detect artifacts of the compression process even at high bitrates, and transcoding between compressed formats will cause generational loss by amplifying existing artifacts and creating new ones. However, this is not really relevant to the discussion of audio woo as it is actual double-blind demonstrable fact. If for some reason you do need to tweak a digital signal, it's possible to patch a computer or effects processor into the analog stream like musicians do, but you'd likely have to write your own effects filters in a language like Nyquist[note 18] or build them yourself in a manner similar to an analog stomp box for a guitar.

Some people get confused by seeing a digital signal depicted as a jagged squared approximation of an analog signal. The magic of Nyquist's sampling theorem is that, for frequencies below 2N, it does in fact work out as identical - the jagged bits are completely filtered out.[12] But people don't understand this and think anything analog is magically better, or alternately that if 2N is good then 4N or 8N must be better. Classical audiophiles now consider 24-bit 96kHz (usually as a FLAC) the acceptable minimum, even though no double-blind tests have proven that 24/96 can be differentiated from CD (16/44.1). Linn, which markets extremely pricey systems to audiophiles, typically offer 24-bit 192kHz, which is pretty closely analogous to selling video that stretches from far infrared to X-rays as if that would make a movie look better. Note that while recording and producing music benefits from high resolution,[note 19] A/B/X testing has consistently shown no perceptible benefit to playback by the end listener. In fact, playing ultrasound through speakers can actually degrade the playback through intermodulation distortion.[13]

The A/Tuning thing[edit]

See the main article on this topic: A440

Some people believe that the A440 tuning used by most modern musicians is ugly-sounding, harsh, or even harmful to one's mental health. Some even claim that non-A440 tunings (such as the "solfeggio frequencies"[14]) are beneficial or healing. A vast majority of such claims are notably bullshit. A testament to the can-do spirit of the fringe, some websites offer a service that will convert one's music library into non-A440 tunings, such as A432 or C528. Of course, all this conversion takes is basic sound editing software.

Tuning does matter, but only when we are talking about the relative intervals between notes (just intonation vs equal temperament). Some people have absolute pitch, so they can tell the difference between absolute tones, but even people with perfect pitch may not notice when listening to music on a day-to-day basis. We are not born with pitch pipes in our brains.

When demonstrating the A432 or other tunings, cranks usually play an A440 piece after an A432 one. The reason why the A440 sounds ugly afterwards is because your brain heard something in A432 immediately before it, so it sounds out of tune. If the video started with A440 and immediately changed to A432 afterwards, the A432 will sound a bit flat.

Magical cables[edit]

Audio cables are inherently very cheap to make, store and transport. The vast majority of cable sellers do not manufacture anything: they choose generic products from industrial cable makers, add some cosmetic changes for brand differentiation and then apply huge markups to the retail price. This is abetted by the fact that audio cables have practically zero maintenance, spare-part, and after-sales service costs.

Audio dealers also favor expensive cables, as they can add their own excessive markup on products that cannot malfunction and will never require servicing, spare parts, or any kind of dealer support. Many dealers utilize a "fake choice" trick on unsuspecting consumers: they are quick to loan a variety of cables for a home trial, giving the consumer the "choice" of keeping and paying for the cable they prefer and returning the rest. The returned cables have no sign of having been used before and retain their "brand new" status and perceived value. The consumer is thus fooled into making an entirely free choice (between similarly overpriced products) and the dealer clinches a profitable sale regardless.

Power cables[edit]

Over-engineered and insanely expensive power cables are perhaps the easiest product to dismiss. The claim that 6 feet of $1,800 power cabling improves sound quality is ludicrous for the same reason that using such a cable won't make a DVD player display a sharper picture, although similar claims are made to that effect.[15] The claim also ignores the many hundreds of miles of boring cable being used to deliver the electricity to the house of the audiophile.

The effectiveness of the magical power cable would rely on the following assertion: The characteristics of the electricity are being altered by their passage through the magical cable. In more scientific terms, certain cables can, in fact, decrease resistance, heat and long distance power losses, however when it comes to a home audio system, none of these are relevant. Resistance of the cable is tiny compared to internal resistance, heat is not an issue, and you're not going 3000 miles with your audio signal. The cheap copper cable your equipment came with is more than adequate.

Luckily this can be very easily tested, although this is not something to do at home! The following steps are dangerous to you and your equipment, and provided for illustrative purposes only. Do this stuff at your own risk.

You could hook-up an oscilloscope or a spectrum analyzer directly to the mains line. This provides a baseline measurement. Next you can take the same measurements with both a regular power cord, and then with the expensive cable.

The AC mains current will run through a transformer in order to adjust the power before it's routed to the various components of the equipment. The same measurements can be applied to the outputs of the transformer to see if swapping the power cords makes any difference. This is ideally done as a blind test, so that the person taking the measurements doesn't know which cable is currently being used. At this stage, it's unlikely that there will be any difference in the readings.

If there are no obvious difference found in these tests, then how on earth could the power cord be making a difference to sound quality? Fairies cleaning the electrons in some way invisible to physics?

Data cables[edit]

All data transmission standards specify a set of minimum performance parameters a cable must meet in order to be certified as standards-compliant. Even if it's true that a super-engineered HDMI cable will have a better physical signal quality than a philistine HDMI cable, in the end it just won't matter for the simple reason that both cables fulfill the minimum specifications. The transmitted bits will be exactly the same when it reaches the TV. This is even more funny when you consider that HDMI uses transition-minimized differential signaling,Wikipedia's W.svg which uses two wires to transmit two "mirror copies" of the signal to cancel out any noise, as well as incorporating an error-correcting code — the standard is designed to provide perfect transmission with lousy cables. The same is true for practically every other data transmission standard.

Bits are bits. But you can still get $500+ Ethernet, USB or digital interconnect cables if you are willing to ignore all that rubbish about how digital signals aren't affected by cable quality at the short distances found in the average home.

Cable directionality[edit]

Some audiophiles believe that a cable will perform differently depending on which way it goes (e.g. which way the electrons move along the cable). Naturally, this is completely bogus, because cables are not made of diodes. A blind test found that the subjective choice of better direction is completely random, even for cables cut from the same spool.[16] Some audiophiles are confused by stickers on cables with an arrow pointing to one end. These arrows aren't pointing in the direction that the signal "travels", but mark which end of a ground-lifted cable is connected to ground.

Abuse of science[edit]

As more and more of the audio chain becomes integrated and non-user-serviceable, some hobbyists have begun to focus on small bits of solid-state physics in the attempt to tweak ever smaller performance gains out of their equipment. As a result, they invoke much pseudoscience in order to justify massive cost outlays for things like marble turntables and $100+ power cables.[17]

  • The green marker thing: It was rumored at one time that coloring in the edge of a CD could make the disc sound better; in response to skeptical comments that "bits is bits" (i.e. digital data sounds the same no matter what source it comes from), some audiophiles have offered the ad hoc idea that the green marker prevents stray laser reflections... or something. Though no longer as widely believed, the markers are still available and sold explicitly for that use. Note that this is an entirely separate idea from using a marker to break copy protection.[18]
  • Treating CD surfaces: While it is true that a clean CD is a good thing, a cult developed around "treating" the playing surface of CDs with Armor-All (specifically) to improve the sound.
  • Skin effect: In radio engineering, signals in the VHF, UHF, and microwave bands sometimes tend to congregate on the outside of a conductor, increasing the effective resistance of the conductor and causing signal leakages at sharp bends in the conductor, requiring careful laying of antenna and patch cables to avoid signal loss. While the effect is negligible to nonexistent at audio frequencies, some audiophiles nevertheless place great emphasis on avoiding skin effect.[note 20]
  • Hyperseparation of channels: Numerous audiophile systems avoid stereo power amplifiers, using so-called "monoblock" (i.e. single-channel) amplifiers to completely eliminate interchannel crosstalk. While fairly harmless in terms of function (though not necessarily to the audiophile's wallet), it is generally considered overkill by sound engineers.
  • Obsessively shortening the signal chain: Given the opportunity, many audiophiles would prefer to avoid as many amplification stages as possible, to remove even the tiniest loss of signal definition. As a result, some audiophile systems eschew even a preamplifier, piping the output from the playback device directly to the power amp. Sound engineers find this to be especially hilarious in light of the vast number of op-amps in the mixing boards used to create the recording in the first place.
  • Esoteric cabling: Manufacturers gladly pretty much make up pretend scientific-sounding reasons for why their incredibly expensive interconnects and speaker wires are supposed to sound better. There is also a sub-cult of people who think their speaker wires sound better if they are supported on magical insulators. At least one test found that audiophiles couldn't tell the difference between coat hangers and fancy Monster brand cables used as speaker wires.[19] Super-technobabbleific woo is particularly hilarious when applied to digital cables (S/PDIF, HDMI, etc); again, bits are bits and bit loss is often more than readily apparent.
  • The magical clock: A particularly ingenious scam artist once sold a "specially modified" digital alarm clock for $400 each. Plugging it into the mains outlet was supposed to effect amazing improvements in the quality of sound. He also sold a number of other strange things, like little bits of foil to stick to things. The subjectivist audio press were duly impressed.
  • Another outfit, that also makes a magic clock,[20] also offers to teleport better audio and video reproduction thousands of miles — over your phone. Genius.[21]
  • Brand power: The first-generation PlayStation is supposedly actually a hifi-quality CD player, because, hell, it's a Sony. When skeptical people opened one up and found fairly cheap parts not particularly similar to ones found in Sony's top-of-the-line equipment, the audiophiles retorted, "it's the connectors, duh".[22] People remain somewhat unconvinced.
  • Completely insane: Taping bags of magic aquarium gravel to your cables, or even just putting a jarful of them in your listening room, improves the sound through "atomic mechanisms".[23]

Sometimes "right"[edit]

While many of the claims made by audiophiles are rightly derided as pseudoscience or woo, there is a track record of so-called "golden ears" being right about some things that "engineers" failed to get right. A few examples:

  • Early solid state amplifiers (and even some later ones), while measuring far better than their tube (valve) predecessors, sounded worse. It turned out that inadequate amounts of negative feedback, while measurably reducing the total harmonic distortion (THD), were actually increasing the perceived harmonic distortion, by creating new higher-order distortion components that are more audible. Reducing the THD number does not necessarily reduce perceived distortion, since low-order distortion components are masked more by the ear. Of course, once the engineers realized this, they solved the problem by applying lots more negative feedback to reduce all the harmonics to inaudibility.[24] Nevertheless, an irrational aversion to any form of negative feedback persists to this day.
  • Early transistor amps were also producing large amounts of "crossover distortion", a kind of distortion that is caused by transistors switching on and off.[note 21] This has been greatly ameliorated by "idling" the transistors during the off period of their duty cycle (changing from class B to class AB) and applying even more negative feedback.
  • Early CD players were accused, in spite of their being marketed as "perfect sound forever", of sounding nasty compared to analog equipment. The "brick wall" filters at around 20-22 kHz used to keep digital artifacts out of the reproduction chain were creating unpleasant phase effects in the audible region. Also, some of the early players only had 14-bit D/A converters.[25][note 22] Better ways of eliminating these artifacts (oversampling converters) eliminated this problem. Many early CDs were also mastered poorly, since engineers were not used to the nature and requirements of the format, and this led to them sounding harsh.
  • Most contemporary CDs are mastered very aggressively, with the purpose of their being listened to in very noisy environments (car radio, personal audio devices used in urban environments, etc). The trend has been named "The Loudness Wars" and makes for CDs that sound too loud and too compressed in a normal home audio situation. This kind of mastering could not (and still cannot) be done on vinyl records, as they would then present excessive tracking demands to the pickup cartridge and cause distortion or record skipping. Consequently, an LP version of the same music can sound much more naturally mixed and mastered than its CD equivalent, which has been artificially "optimized" in the studio for use in noisy environments. Some compare the two and mistakenly attribute this difference to analog vs digital, without realizing that they are listening to two different masters. This is not an inherent flaw in CDs, but the result of deliberate marketing decisions made by music sellers.
  • Some high end headphones have a very low power draw (high impedance), meaning that when hooked to a standard PC or CD/MP3 player jack, they cannot draw enough power, which decreases sound quality. A small, fairly simple amplifier can greatly increase quality under these circumstances. These units are small enough to fit inside a mint tin, very cheap, and so simple that anyone who can read schematics and solder can make one themselves.
    • That said, the popular "CMoy" designs drive headphones using "jellybean" op-amps that also aren't designed to drive low-impedance headphones, leading to audible problems and long forum discussions about which op-amps "sound the best",[26] when a proper design wouldn't have any audibly-detectable differences at all.[27][note 23]
  • Over very long lengths, cables can affect audio quality if the gauge of the wire is insufficient. Thin speaker cable at lengths of maybe 50 feet (15 meters for those living in the 19th century or later) or more will show a noticeable drop in quality.[28] Similarly digital cable over very long lengths will show noticeable signal degradation. However these are issues that could only really affect very large venues such as stadiums and concert halls where industrial grade (and relatively cheap) cable is used. This is the grain of truth that is heavily manipulated to sell very expensive cable to the monetarily overburdened.
  • S/PDIF transmits the signal and the clock on the same wire, through a special format called "biphase mark code" in order to support a wide variety of signal rates. If insufficient care is taken in designing or implementing the clock reconstruction process, this can result in "jitter" as the bits are sliced up wrong on the receiving end, which generally increases noise in the reconstructed signal.
  • Audiophiles often modify their equipment by replacing cheap operational amplifiers through more expensive ones (some as expensive as 50$). Expensive operational amplifiers can actually be more technically superior. But the music already passes a long chain of audio equipment when being recorded. And even the professional equipment is mostly made out of cheap operational amplifiers like NE5534/NE5532 for about 1$. So why should the audiophile amplifier (which is only the last link in that chain) give any significant improvement to audio already "contaminated" by the cheap operational amplifiers? Also audiophiles often do not consider the rest of the electrical circuit when changing the operational amplifiers. As a result the distortions can become worse even when a cheap operational amplifier is replaced by a superior one.

There are other examples, but, sadly, these truths tend to encourage careless audiophiles to set greater store than appropriate to every wacky claim put forward, both by manufacturers and "golden ear" reviewers.

Shit or get off the pot[edit]

Audio quackery is now in the sights of James Randi, who is putting his $1 million prize where his mouth is — "simply because if some of their claims were true, they would be paranormal."[29] No takers so far, a few pikers.[30]

Professional sound[edit]

There are people who do work with recorded music for a living, and if they don't get it right they lose their jobs. Studio recording relies on all-transistor analog stages and digitizing the signal in the highest quality possible. Depending on the budget and style of the engineer it is uncommon to still record or mix to tape. In higher end studios most processing is done in the digital domain or "in the box." Studio monitor systems use solid state amplifiers, and speakers with predictable characteristics so they can hear precisely what they are recording or mixing. Although low quality speakers known as "truth boxes" are used to make sure the mix will sound good in a low-fidelity playback environment, high quality speakers and systems are also used to make sure the recording is being mixed and mastered to the artist's or producer's liking. The only tubes in evidence are used in some microphone preamplifiers, vintage compressors, and of course in instrument amplifiers where they are prized for either their sweet sound or for their pleasing characteristics when overloaded.

A problem, which has been around for a long time, is the over-compression of recordings so they will always be "loud" on the radio. See loudness war.

In spite of this compromise, often provided for or demanded by the marketplace, one thing is notable in the professional sound recording and reproduction environment: professional sound engineers ignore virtually every bit of audio woo promoted by charlatans and worshiped by sufferers of nervosa audiophilia, since it is wasteful to spend the customers' money on hardware that does nothing.[30]

If you ask a pro-audio person for help with your hifi sound, they'll tell you how to fix the room first. Probably a lot cheaper too.

Useful things you can do that will actually work[edit]

Fix the room first. You'll be amazed how good your old stuff sounds when you're hearing it in a room with decent acoustics.

You can also place the speakers closer to your ears. This can significantly increase the ratio of the sound coming directly from your speakers relative to the sound reflected by the walls of your room. But do not get too close or you might start hearing the slight noise caused by the amplifier. Or avoid the problem of the room acoustics altogether by using headphones. However note that the usage of headphones means sacrificing the non-simulated HRTF-effect (head related transfer function) which is the only justification for the existence of surround systems. By using headphones you also sacrifice some perception of the deep bass which usually slightly shakes the rest of your body. This can be compensated by using bass shakers.

Spend the bucks on decent speakers.[note 24] Everything else in the chain has pretty much reached the point of diminishing returns, so speakers are the lowest-fidelity component left, and spending more money can still result in noticeable gains. Note that, however, many expensive speakers are also rubbish, just to keep the decision interesting.

Use speaker cables with a decent gauge of wire, 14-18 AWG, especially if the run from the amplifier to the speaker is long. The resistance of the speaker wire can reduce the damping factor of your system. What this means is that the amplifier doesn't have as much control over the mechanical movement of the speaker. The result is most noticeable at low frequencies, causing the bass to lose "tightness." So don't use that cheesy thin wire that you found in the basement, though there's no need to go overboard with expensive speaker cables.

In particular for analog playback devices, avoid sharing a circuit with a large inductor like a fan, air conditioner or a particle accelerator. Use of a surge suppressor can clamp down on transient voltages and a 1:1 transformer can cut down on harmonics. Most amplifiers, though, will already use a transformer which naturally evens out circuit harmonics. A dedicated ground might help in some situations as well. However, all these are meant to correct problems associated with distributed power and there's no "performance gain" by using them when no disruption is present.

In computer audio, sound cards make a slight but real difference.[31] Sound chips integrated on a computer's motherboard were once notoriously bad, in some cases leaking noise so badly that moving one's mouse would produce a noticeable buzz, but their quality has improved significantly over the last few years. Speakers/headphones still make the biggest difference for your money, but if your system is affected, or you're interested in the additional features (unrelated to reproduction quality), consider purchasing a cheap discrete sound card. If you have a pair of high impedence headphones (Generally high end units), your sound quality can be noticeably improved by purchasing a sound card with an amplifier. Most onboard chips lack this capability and are therefore not supplying enough voltage to the device. They also often have a high output impedance of about 100 Ohm which can introduce minor measurable distortions in the frequency response if headphones are connected directly. Headphone amplifiers eliminate the problem by providing an output with negligibly low impedance.

Another good idea is the usage of an external sound card in order to shield the sensitive analog circuits from the EMI caused by the fast switching internal components of the computer like the power supply, the CPU and the graphics board.

Other types of audio woo[edit]

Ultrasonic pest control[edit]

Ultrasonic pest control is a method of using ultrasound, sounds above the range of human hearing (generally >20kHz), in an attempt to repel pestilent insects or rodents. Devices that use ultrasound in an attempt to repel pests are widely marketed. Generally, ultrasound does not work, and when it gives a false sense of security (e.g. prevention of bites from malarial mosquitoes) it can actually be dangerous.

  • Bugs: Ultrasound can have an effect on some arthropods.
  • It is highly effective on crickets but has no effect on cockroaches.[32] A 2007 review of ultrasound use for mosquito bite prevention found that it was not effective.[33]
  • Entomologist Bart Knols concluded that there is no scientific evidence that ultrasound repels mosquitoes.[34]
  • Rats: A study of commercial ultrasound on rodents concluded that the devices were marginally effective and that rodents rapidly became habituated to the devices.[35]

In June 2012, Brazilian station Band FM broadcast a 15kHz tone under its music and told its listeners to "relax in the open air without fear of getting bitten" by mosquitoes.[34] The 15kHz broadcast was sponsored by the magazine GoOutside.[34]

See also[edit]

External links[edit]


  1. Firstly, "audio woo" is not sound science, as in — the actual science of soundwaves. Secondly, as the term betrays, "audio woo" is not actually a sound science, but a pseudoscience.
  2. Often lamented as having disappeared with the introduction of transistors, and then the compact disc.
  3. Even-harmonic distortion, resulting from so-called asymmetric soft clipping.
  4. As it's substantially more robust than optical or magnetic media
  5. This process can be slowed quite considerably by the use of a high quality stylus profile such as Shibata or line-contact.
  6. a CD, which can sample just outside the range of human hearing, can produce a much more faithful representation than a standard vinyl LP.
  7. The actual situation makes up the greater part of a textbook on signal processing, or at least a fair handful of Wikipedia pages.
  8. There's a couple of different ways of sending digital signals. For our purposes we'll focus on electrical rather than optical transmission; on the consumer level, optical connections like TOSlink are subject to the same sort of woo but it makes even less sense. However optical connections provide electrical isolation with the potential of eliminating ground loops and keeping away high frequency noise caused by fast switching electrical components like graphics boards.
  9. In simple terms, at least one point for the peak of the wave and one point for the trough
  10. For example, a very rough approximation of a sawtooth wave with 8-bit sampling might look in a hex editor something like: 00 20 40 60 80 A0 C0 E0 00 20 40 60...
  11. This is somewhat unnecessary to the point of this discussion, but for examples, check the Wikipedia articles on Frequency shift keyingWikipedia's W.svg, Phase shift keyingWikipedia's W.svg, and Quadrature amplitude modulationWikipedia's W.svg for three examples of how it's done and Digital Radio MondialeWikipedia's W.svg for a widely-known example of a real-world application.
  12. Or losslessly compressed like FLAC or Apple Lossless; lossy compression such as MP3 is a different story and really isn't a signal chain issue.
  13. If you want to be really technical about it, OSI levels 1 and 2.
  14. A quick case study: Audio journalist Malcolm Steward wrote an article in August, 2010 describing the alleged effect of swapping out an SATA cable in his NAS box on the sound quality of a very expensive digital media player. After getting crucified by legions of mainstream computer geeks who knew what he was claiming was beyond impossible, Steward threw a special-pleading temper tantrum for the ages and shut down comments on the relevant blog posts.
  15. To be more accurate there are also so called metastable states with pretty nasty properties, but with proper chip design they are so extremely improbable that they are likely to not occur even once in your whole lifetime.
  16. Through automated retransmission or ECC in case of some other standards
  17. DVDs and Blu-Rays even more so, since they don't deal in raw data streams at all but computer files -- if your DVD isn't being read properly, the signal chain is the least of your problems.
  18. Nyquist is a loosely LISP-based programming language designed specifically for processing digital sound files; the original web page can be found here, and the most commonly deployed version is part of the Audacity multitrack audio editor.
  19. This is because a track can be run through hundreds of filters on the way to the final mix.
  20. It is of some concern in high-bandwidth video applications, but for the most part people don't obsess nearly as much over S-Video cables.
  21. I.e., each of the pair of transistors only conduct one half of the waveform, and then have their outputs combined
  22. Phillips had initially specified CD as 14-bit and duly developed a 14-bit DAC, the TDA1540 - then Sony came in and said "no, we want 16-bit." Phillips went "shit" and their initial CD players had to make do with the 14-bit DAC until they released the 16-bit TDA1541 in 1985.
  23. Quote, "If you compare overloaded op amp A against overloaded op amp B you may hear some differences in their highly distorted performance. But that’s only because you’re stepping on their tails and making them screech in pain."
  24. This message was not placed by the one RationalWiki contributor who makes and sells speakers for a living, and the implication is not that you consider buying new speakers from this person today!


  1. Write up of double-blind test for audiophile equipment
  2. Audiophiles and the Limitations of human Hearing
  3. Positive Feedback's Review Philosophy
  4. The Audio Critic issue 26 The 10 Biggest Lies in Audio
  7. Skeptoid episode #303, Are Vinyl Recordings Better than Digital? Emphasis in original (transcript).
  8. The Audio Critic issue 26 The 10 Biggest Lies in Audio
  9. Axiom Audio
  10. The basics of bi-amplification.
  11. Nyquist-Shannon sampling theoremWikipedia's W.svg
  12. Xiph.Org, "Digital Show & Tell"; the relevant part starts at about 3:36, esp. from 5:50
  13. Chris Montgomery, "24/192 Music Downloads are Very Silly Indeed"
  14. Solfeggio frequencies bring you health, balance, and harmony
  15. AC power filter: I can't see a difference, but I know it's there!
  16. Audio Engineering Society Section Meeting Report: The Truth About Audio and Other Cables
  17. $1,800 for a power cord? I'll take 2!
  18. CD Crack: Magic Marker Indeed
  19. Do coat hangers sound as good as Monster cables? Yes. Yes they do.
  20. Machina Dynamica's Clever Little Clock
  21. Machina Dynamica's Teleportation Tweak
  22. PlayStation 1: The audiophile's dream?
  24. The F-word, or, why there is no such thing as too much feedback - Bruno Putzeys
  25. The CD Story (Kees A. Schouhamer Immink, one of the engineers who created the format); Meridian 208 CD player/preamplifier (Stereophile, December 1990)
  26. Best sounding cheep op-amp for CMoy's?
  27. Op Amps: Myths & Facts
  28. Misleading Wire Demonstration
  30. 30.0 30.1
  31. Review of sound cards, including blind listening tests and measurement data
  32. Bhadriraju Subramanyam (Subi) (2001). Ultrasound and Arthropod Pest Control: Hearing is Believing!. Kansas State University.
  33. Enayati A, Hemingway J, Garner P. (2007). [Electronic mosquito repellents for preventing mosquito bites and malaria infection]. Cochrane Database of Systematic Reviews.
  34. 34.0 34.1 34.2 Ultrasound mosquito repellents: Zapping the myth by William Kremer (11 December 2012) BBC.
  35. Electronic Rodent Repellent Devices: A Review of Efficacy Test Protocols and Regulatory Actions. University of Nebraska — Lincoln.