The Audio-Transparency Initiative focuses on shifting a listener's attention from gadgets and technology to music and its authors. To this end, clear guidelines are proposed for designing and manufacturing audio equipment with extremely low sound degradation, inaudible to human hearing. A transparent audio path - an ideal channel for communication between music authors and listeners - should become a new norm and a standard commodity. The accompanying study of the audio quality in the market of portable players is aimed at (1) defining the required level of transparency for audio equipment and (2) showing how far current portable players are from this level. Exceptional audio quality at low prices can be achieved through the united effort of music lovers.
Music is the universal language of mankind.
Henry Longfellow
Music is everybody's possession.
It's only publishers who think that people own it.
John Lennon
It is not currently possible to say with certainty how and why our species of Homosapiens started to sing (hunting, rituals/dances, lullabies, language-genesis, etc.). Our closest relatives in the animal world - chimpanzees - have no such musical behavior at all (and poorly developed larynxes), but, for example, among birds, it is common. At the same time, in all known human communities, musical culture in one form or another is inherently present, and some researchers believe that the Neanderthals were even more musical than us. Considering that the oldest known musical instrument is about 37000 years old (primative bone-flute with holes), we can confidently say that our musical culture has its roots in the very earliest stages of the emergence of humans as a species, and that music itself is one of the oldest forms of social interaction.
With the emergence and extinction of new hearths of human civilization, our musical practices also developed. Despite local successes (ancient Egypt, India, Greece, etc.), musical culture up to the Renaissance was quite basic and most people could easily be both listeners and performers. The rise of Western civilization at the end of the Late Middle Ages gave a powerful impetus to the development of science, technology, and culture as a whole. The deepest and most important component of any culture - music - also experienced a rapid blossoming. There appeared advanced musical notation, professional composers and performers, new musical genres and instruments, a music economy, entrepreneurs, sound recording and distribution of the recordings to listeners. A deeper understanding of the structure of music appeared, its regularities, peculiarities and perception by humans. In the context of the current initiative, two aspects of this musical evolution are most interesting.
Musical instruments. Since about the 15th century, the variety and complexity of musical instruments increased drastically. The separation of musicians from listeners began and reached its peak at the end of the 20th century. With the advent of electronic musical instruments, sampling techniques and personal computers, the process of separation began to slow and even reverse. It became possible to create music at home without requiring an education in music. The rapid development in recent years of AI technology has led to the emergence of so-called generative music [Mubert, Jukebox ...]. Such "artificial" music in terms of its technical and, most importantly, artistic characteristics is already not so different from the human creation (we often hear it now without knowing the origin). The mass availability of AI technologies will inevitably lead to the explosive growth of people making music, further blurring the boundary between musicians and listeners. Each person will have the opportunity to compose and perform new music by training a neural network with some selected music material and the author's music experiments - playing instruments, and/or singing. The "quality" of such music may be questionable but the quantity will be huge and there will surely be some outstanding examples.
Music economy. Somewhere around the turn of the 18th century, more elaborate music started to develop and move beyond the realms of churches and the mansions of noble people and began to flourish on its own. The first music intermediaries and managers appeared, helping musicians to organize performances, and to inform and encourage listeners to attend those performances. The commercialization of music had begun. This process also reached its peak at the end of the 20th century, when most of the music business found itself in the hands of the four record companies - EMI, Sony Music Entertainment, Universal Music Group, and Warner Music Group. In the music market, they set the rules for both musicians and listeners. Over two centuries, the humble helpers had turned into the owners of the world music business, controlling almost any interaction between musicians and listeners, and taking the bulk of all profits. To be fair, it should be noted that despite such an unhealthy commercial situation, the recording industry in the 20th century produced a huge number of real musical masterpieces that will be in demand for several generations of listeners. And again, the technological progress in the late 20th century changed the rules of the game. Internet, compact audio file formats (mp3, FLAC, etc.), and decentralized file-sharing protocol (Bittorrent) have formed an open technological environment for direct communication between musicians and listeners. During the last two decades we have been actively searching for new forms of such interaction: personal websites/blogs of musicians, services for promotion/sales of their music (MySpace, Soundcloud, TuneCore, FB Social Audio), free distribution of music by authors, payment by the formula of "pay what you want", direct financial support of musicians by listeners and participation in their releases. Despite the serious complications of this process, there is little doubt it will be successful because musicians and listeners need each other, they have all required network technologies for self-organization, and the differences between them, as mentioned above, are becoming increasingly blurred and conditional. Conversely, any closed proprietary mass delivery channels for music on any medium would seem to have no future. Meanwhile, new types of intermediary services will be in demand as listener navigation in the new boundless ocean of music becomes more and more complicated, and musicians require increasingly sophisticated technical support. It is worth adding that it will remain very challenging to create great works and hits.
Thus, having made dizzying progress together with Western civilization, musicians and listeners are uniting again. The question of whether to listen to, or to write, music will soon be a question of mood and preference. However, another barrier between musicians and listeners remains.
Playback obsession
Following the advances in sound recording that began in the late 19th century, rapidly-increasing technical complexity resulted in musicians starting to require the assistance of sound engineers. The quality of the final product - the master record - became highly dependent on their knowledge, experience, and musical taste. Listeners also needed technically advanced devices for sound reproduction. While the technology and equipment are much more complex for recording than for playback and the skill of the sound engineer has a significant impact on the final quality of the recording, the quality of the listening experience has been mostly associated with playback devices. In Hi-Fi/Hi-End magazines, forums, websites, etc., the characteristics of recorded sound such as detail, resolution, imaging, timbre, layering, sound stage depth and width, fidelity, transparency, etc., are invariably discussed only in the context of the playback audio path. It is difficult to say why such an unnatural discourse has emerged. Perhaps it can be explained by the fact that the first playback devices were truly of poor quality, and their advancement was seen as the main potential for improving the listening experience. Perhaps economic factors also played a role - the nascent market for playback equipment looked promising, and so the issue of sound quality was debated mostly within the marketing of these new consumer devices. But whatever the reason, this crafty approach remains dominant to this day and, it should be noted, is fully in the interests of manufacturers of consumer audio equipment.
Flawed audiometric
This confusing tradition is favored by the fact that a listener has the last word in determining the sound quality of an audio device and there is no reliable method of measuring it with an instrument. The traditional set of objective audio parameters - THD, IMD, SNR, frequency response, etc. - does not correlate well enough with subjectively-perceived sound quality. This was well known to audio engineers from the very beginning. With the advent of digital-audio technology, this weakness of traditional audiometric (TAM) became even more evident. Today, only an experienced audio specialist can benefit from the results of traditional measurements; the average user is unable to interpret them correctly. While a manufacturer of audio equipment necessarily has such a specialist in the staff and no doubt clearly understands the actual quality of its products, the listener has to rely only on his/her feelings and impressions from listening. And the listening experience is strongly influenced by many extraneous factors - the appearance of the device, its brand and price, reviews and friends' advice, etc. In short, the manufacturer knows everything about the product; the consumer knows little more than nothing. Such an information asymmetry in the market creates the opportunity for a manufacturer to pass off lower-quality goods as high-quality [Information Asymmetry, G. Akerlof]. This is exactly what has happened in the consumer audio market and, to a lesser extent, in the professional market. Taking advantage of this information asymmetry, manufacturers have gradually become more focused on marketing rather than research and development. As a result, today's audio equipment prices are mostly backed by quasi-scientific marketing stories. Thousand-dollar audio cables and fabulously expensive high-end products are the most egregious manifestations of this phenomenon.
This exaggerated importance of modern playback equipment is the last barrier between musicians and listeners. This barrier can be safely removed with the help of a new approach to designing an audio path and an assessment of its quality. The integral part of this approach is the new audiometric - df-metric, which was developed to overcome the shortcomings of TAM [Audio metric that makes a difference].
The basic idea of df-metric
In its simplest form, the basic idea of the new audiometric can be explained as follows. Since sound is entirely determined by the shape of the sound wave, the task of preserving the sound quality is the task of preserving the waveform of a signal along the audio path. The level of degradation (distortion) of the waveform is measured with a special parameter - Difference Level, dB [Difference Level. An objective audio parameter]. The main advantage of this parameter is the ability to measure the degradation of any signals, including real music. When using the latter, this parameter correlates well with the results of listening tests.
Why traditional audiometrics work poorly
Experiments with signals of different waveforms that were used for testing real audio devices helped to identify the main cause of the low efficiency of TAM. The figure below shows the results of testing eleven players with signals of various waveforms: music, noise, rectangular, triangular, and sinusoidal signals [the source: Audio Quality of High-End Portable Players]. The devices in the picture are sorted by Df levels of the real music signal.
 | Test of portable players with signals of different waveforms: real music [Test set of music material "Variety"], noise signal simulating real music (BS EN 50332-1), rectangular, triangular and sinusoidal signals. The correlation of Df levels of each signal with Df levels of the music signal is indicated. |
We can see that the noise signal correlates best with the music signal (r=0.99), and the correlation with the sinusoidal signal is the lowest (r=0.69). It should be noted that when using a sinusoidal signal the value of the Df parameter is equal to THD+Noise of TAM (they differ from each other by 3 dB). The signals of different waveforms do not degrade accordingly or consistently. Each time we measure the quality of a group of devices with a new signal, we get a new ranking of their quality. Thus, the initial assumption that smaller distortion/degradation of one signal (typically sinusoidal) results in smaller distortion/degradation of other signals turns out to be false. A device that reproduces a sinusoidal signal more accurately than other devices may in fact be less accurate in reproducing a signal of a different waveform.
If the results of measurement depend on the type of test signal used, there is a question - which test signal should be preferred while measuring? The answer is obvious - real music/speech signals (or its noise equivalent). Audio equipment should be designed to work exactly with such signals.
Recent attempts to expand the list of test signals used in TAM can increase its efficiency only to a small extent because of the low correlation between measurements with different test signals. Today, TAM is reminiscent of Ptolemy's model with the Earth at the center, where an ever-increasing number of new epicycles had to be introduced to predict the positions of the planets more precisely. Finally, it was replaced by a heliocentric model, which proved to be both simpler and more accurate. An audiometric can provide similar benefits by eliminating the use of narrow technical signals to predict the sound quality of audio devices. There should be real music/speech signals in the center.
Features and benefits of df-metric
In the df-metric, technical signals are used only for testing specific aspects of device performance and are interesting mainly to developers and engineers. The actual sound quality of a device is measured with statistical methods using a large array of varied sound material (music and speech).
Benefits of the new audiometric:
- a fairly simple and inexpensive way to measure Difference Level
- df measurements give a comprehensive picture of device audio performance
- higher correlation of measurements with subjective sound quality due to use of real-world sound signals
- easier interpretation of measurement results, understandable to the layperson
- Df parameter can be used for both analog and digital signals (regardless of sample rates for the latter)
- df-metric helps to determine the lower threshold of sound signal degradation, at which this degradation becomes imperceptible for any listener (or a majority of listeners). In other words, it helps to determine the required transparency level of an audio path. Such transparency level can be determined both theoretically and based on measurements of real audio devices in the market. If necessary, it is possible to define several additional classes of semi-transparency.
One disadvantage of the Df parameter is its indifference to the nature/type of signal degradation. As we know, not all distortions are equally perceptible. However, all current audio engineering experience shows that weighing different types of degradation of real sound signals according to psychoacoustic regularities is hopelessly difficult. Their noticeability significantly depends both on the nature of the musical signal (genre, saturation, tempo, ...) and on the peculiarities of perception of a particular listener - his/her listening experience, musical preferences, features of his/her hearing (age), and even on the cultural musical environment in which the listener grew up (perception of consonances and dissonances). With such a set of complicating factors the establishment of any universally agreed objective audiometric that takes them all into account is simply impossible. Fortunately, there is no such need anymore.
The engineering approach to sound quality; a new paradigm
The current level of technology allows design and production of audio equipment with low level of distortion/degradation of a music signal. Available data measurements of real audio devices show that the audio transparency level for different types of devices is in the range from -70 dB to -90 dB and some devices on the market already provide such accuracy. In other words, today it is easier to provide the required transparency of an audio path by engineering methods than to sort out which distortions are acceptable due to their low audibility for hearing, and which should be excluded. The paradigm of inevitable distortions can be safely and permanently dispensed with; this is just the breeding ground for marketing abuses in the audio industry. This is especially true for manufacturers of High-End equipment, who are essentially the sellers of distortions, deluding their customers into believing their distortions are "the most musical, fully revealing the richness of recorded sound". The new paradigm of transparent audio (lossless digital/analog audio path) is more honest and allows us to shift the focus of listeners' attention from manufacturers of audio equipment to the creators of recordings [The Honest Audio]. Those in the studio should determine the warmth, depth, detail - the characteristics of sound tirelessly discussed in magazines and on sites devoted to playback equipment, supported by advertising budgets of audio manufacturers. The discussion of all those sound nuances with the manufacturer makes no more sense than a discussion of the content of letters you receive from the postman. Any sound playback equipment is just a communication channel for an audio signal and the sound quality of this channel is fully determined by only one parameter - the accuracy of music signal reproduction - the transparency of the channel. If, for some reason, achieving the required level of transparency isn't possible, it might make sense to allow certain distortions using our knowledge of psychoacoustics, but such exceptional cases are increasingly scarce nowadays.
Besides strengthening the role of authors, musicians, and engineers, the proposed paradigm has several additional features and advantages:
- Easy customer control of the quality of audio products thanks to a reliable and affordable measurement method.
- Recovery of consumer audio market by displacing unnecessarily expensive devices of dubious quality and replacing them with equipment of minimal price/quality ratio. Outstanding sound quality at minimum price is the next technological step in audio.
- Commoditization of many hardware audio solutions and improvement of their quality thanks to clear guidelines for their design and manufacturing. Everything that produces sounds, can sound perfect. It's not only a question of aesthetics, it is a question of our hearing health too.
- For audiophiles who practice attentive listening, there will be an easy way to achieve the best sound. As the experience of listening to a recorded sound cannot be any better than that achieved in the studio, preparing a listening environment according to studio standards becomes a simple and logical guide. The appropriate recommendations in the sphere of professional audio are well understood. The very division of audio equipment by sound quality (not by functionality) into professional and consumer looks increasingly far-fetched. Ideally, quality-wise, they should be identical. Not the least because the line separating creators of recordings from their listeners is becoming less distinct.
- For those who believe that a recording can sound better than that in the studio, a new market of software plug-ins for creative listening is opening up. A transparent audio path can be easily supplemented with sound processing tools: EQs, HRTFs, correctors of room acoustics and frequency response of speakers/headphones, tube/vinyl sound emulators, enhancers of depth, width, warmth, detail ..., vocal removers and other audio-photoshop filters. The list is limited only by the imagination of developers.
These changes will also affect traditional listening rituals. Instead of heating the tube amps, cleaning the vinyl, and placing the cartridge onto the groove, we will have:
- reading/viewing additional information about the author/artist and his motives for creating the track;
- searching for technical details of the record creation - equipment, technology, drawbacks/mistakes;
- listening to a pair of warm-up tracks of the same style/genre from another author/performer;
- after listening, perhaps leaving a comment on the author's page or even providing some small form of financial support.
Connection ritual is an important procedure for any attentive listener and its variants can be numerous, not only maintenance of the sound system, which soon maybe invisible to the listener (in-wall speakers, control from phone/tablet, etc.).
A step towards better audio
Many manufacturers today can produce sound equipment of the required quality/transparency level. The new audiometric provides clear recommendations for developers as to what technical parameter should be achieved for this purpose. However, for manufacturers to start doing this, they must be sure that (a) the recommended value of the Df parameter provides the required transparency level and (b) there is sufficient market demand for such devices/solutions. Listeners need to send a clear message to manufacturers, with an informed purchasing decision reflecting their preferences.
Both tasks can be solved by testing audio equipment on the market according to the new audiometric. First, such a study will make sure that the metric works and that the best examples of audio equipment have higher transparency levels. Secondly, it will help to determine more precisely the required level of transparency based on the current market overview. For the study results to be convincing and statistically meaningful, the number of devices examined should be sufficiently large, in excess of 100 models. For many reasons this study is easier to perform for specific segments of the market such as Digital Portable Audio:
- This is a popular way of listening to music in good quality both at home and on the go; almost half of all listeners are using top/specialized smartphones for this purpose. Therefore, the results of this segment of the study should be of interest to many people.
- This market segment is rather small, so almost all such devices can be tested, clearly showing who is who in portable audio.
- Portable players usually have a relatively low level of transparency (though there are exceptions), which allows use of inexpensive measurement equipment (for example, the $200 TI PCM4222 Evaluation Module). Therefore, many audio enthusiasts will be able to participate in testing over a relatively short period of time.
- The measurement method was developed/perfected while testing portable devices [hi-end DAPs, beta2, beta1], so there is already a good understanding of both the possible difficulties of the measurement process and the expected results.
Successful experience gained in this market segment can be extended to other burgeoning areas of audio, such as wireless headphones.
Digital portable audio mass testing campaign "Pump.a.DAP" will be carried out:
Who is invited to participate in the campaign
Audio enthusiasts who already have TI PCM4222 Evaluation Module (or ready to purchase it) and who can perform simple measurement procedures. As usual, the authors of the measurements will be mentioned on df-slides with results.
Stores of portable audio, planning to offer their customers high-quality devices with the best price/quality ratio; the campaign will need access to a large number of models that would be very expensive to purchase otherwise.
Audio forums and discussion platforms, ready to provide a special place for discussion of testing progress and working issues.
Scientific and research organizations; this study has a good potential for becoming the basis for the development of new standards in audio.
All music lovers and DAP users who are tired of marketing noise/hype around portable audio, who would like to see a real picture of quality in this segment of the market, and who are willing to support this initiative/campaign by sharing its news or with small donations. You most likely will be the only source of funding for this campaign, which is carried out for the benefit of ordinary listeners, possibly to the detriment of certain audio manufacturers, who are perfectly satisfied with the current market status quo. All donations will be mentioned on the page with the results of this mass testing [Screen of Fame]. If you decide to donate, don't forget to specify the model of the player whose measurements you would like to see. These models will be given priority for testing.
A step towards a better future
The 21st century has already become a turning point in the musical life of the planet. New ways of delivering music to listeners, decentralized music sharing, experiments with new music economy, remastering of old recordings, the democratization of music creation, the increasing use of AI methods for creation, processing, recognition of music and speech, VR and binaural/immersive audio ... At the same time, manufacturers of consumer audio equipment for the most part continue to live in the 20th century and still prefer to earn their money through extensive and sometimes deceptive marketing.
The advent of the Internet created a profound transformation of human society. The main driving force behind this change is broad social self-organization. Music culture was one of the first to engage in this process - P2P Music was ahead of P2P Money. It turned out that many complex technical and economic challenges associated with our music culture can be solved ourselves, using the potential of a global network that can easily connect both listeners to listeners and listeners to musicians. Progress in many other areas that follow will depend on the developments in the music industry.
Could we find and consolidate new practices of direct interaction between musicians and listeners, including new economic models? Or we will rely on third-party services with their internal corporate rules?
Will we be attentive to, and curious about, new authors and their music? Or we will continue to focus on gadgets and technical aspects of sound reproduction, just consuming music content from providers (mostly in the background)?
Will we, listeners and music lovers, be able to influence the audio market according to our interests and priorities? Or we will rapturously look at the manufacturers who still manage/manipulate this market by knowingly shaping the interests of audio technology users?
The answers to these questions will partly determine the future that we choose to create:
a future with intensifying competition and invention of ever more civilized ways of deceiving each other, with infinitely stimulated consumption and decisions made within closed interest groups;
or,
a future that is based largely on cooperation and attention to each other, transparent decision-making, and respect for nature and resources.
The Audio-Transparency Initiative and corresponding testing campaign, designed to shift listeners' attention from technology to music and its authors, is the first step towards a better future. If you would like to participate, feel free to share this #AudioTransparency initiative with your friends and colleagues:
You can also:
Thanks for your support and encouragement! Exceptional audio quality for everyone is not a utopia, but a real goal that can be achieved through the efforts of consumers alone.
Thanks, HypetheSonics for heavy editing the text and especially for the “edge rounding”. Definitely it's much more clear now.
Appendix
A few words in-person
