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Technical History of a Listening Revolution In discussing the technical standards of sound delivered online, it may be helpful to review some of the basics of digital sound technology and especially its evolution in online environments over the last several years. Many of the same principles that apply to digital imaging also apply to digital sound. For both, a measure of resolution is accompanied by bit-depth, also known as word length. Where in imaging pixels per inch define resolution, in digital “sampling” of sound the measure of resolution is Kilohertz (or sound wave frequency) per second. Where greater bit depth in imaging allows for a larger color palette and therefore greater color precision in the digital scan, so in sampling greater bit depth allows for a larger spectrum of tones and therefore greater tonal precision in the digital sample. The advent of the compact disc in the early 1980s set the first widely held standard in digital audio, with a sampling rate of 44.1Khz and a bit depth of 16 bits (or two bytes). The CD offered extended playtime, greater clarity than LPs or tapes when played on most consumer equipment, and a seemingly unlimited number of plays. CDs changed the way music was both recorded and listened to, and according to some not for the better. Audiophiles accustomed to high-end analogue setups in fact called foul early on, as the digital spectrum allowable by CDs clipped out what they considered hear-able chunks of sound, harmonics and nuances not picked up at 44.1/16. Sound archivists, already hard-edged audiophiles with a sense of historical mission, continued to preserve to tape. Fifteen years on, digital technology capable of rendering analogue sound into digital had grown considerably stronger and become tremendously cheaper. A basic consumer computer with a merely decent soundcard could generate better-than-CD quality copies of analogue sources (typically 48Khz/16-bit), while with some modest investment in a meatier soundcard and extra RAM a home computer could make a .WAV file at 96Khz/24-bit (even if this file couldn’t be rendered onto a playable CD without dumbing it down to a 44.1/16 AIFF file). The .WAV file, the audio equivalent of the .BMP raster image, had become the common currency of digital audio recording.2 The drawback of the .WAV file was its size; with a CD-quality 3-minute file taking up around 30,000 megabytes, the format did not lend itself to easy desktop processing or web transfer (especially on a dial-up modem) and thus creators of .WAVs could not easily share them using the internet. MPEG technology, particularly .mp3 technology, mitigated this problem. At work on compression standards for audio visual materials since 1988, by 1992 the Motion Picture Experts Group developed a means of dramatically reducing sound file size. Based on the psychoacoustic principle that humans best hear tones of 2Khz-4Khz (within an overall hearing spectrum of 20Hz to 20Khz), an .mp3 file rendered from an uncompressed source at 128 kilobytes per second (Kbps) reduced an uncompressed audio file by a factor of ten, getting ride of the tonal ranges humans don’t hear so well. This “lossy” compression scheme sliced out audio information from the extreme portions of the audio spectrum, much as the JPEG image rendering system did with pictures, leaving behind what to the human senses might constitute a fair mirror of the original.3 The passable audio quality provided by .mp3, especially when compared to other portable sound packages with inherent limitations (e.g., cassette tape), sparked a revolution in the way people listened to recorded music; or, put another way, changed the face of delivering cultural material to audiences. In retrospect the success of .mp3 appears to be serendipity: By the time .mp3 emerged, consumer technology had developed at a pace where it could capably handle the format, and users recognized that digital music could finally be effectively processed on a desktop and online. Audio quality in this context was secondary; convenience was king in the .mp3, much as it had been in the format’s cassette tape predecessors. Although interests of the recording industry and issues of copyright will not be addressed in this paper, it is significant that .mp3 technology is non-proprietary and that it is the first audio medium that was neither created nor controlled by the recording or broadcasting industry.4 It is difficult to overstate the significance of the cultural shift that has occurred because of this. In the space of four years audio “file-sharing” via .mp3 has decimated the recording industry, redefined popular perceptions of copyright, and given rise to a whole new business model: online music vendors who believe they can offer both an alternative to the dubious business practices of their traditional recording industry rivals, as well as a convenient way to legally own cheap tunes. However, the emerging online .mp3 giants are haunted by the populist stance of the lamented Napster mach 1, a file-sharing software of and by the people whose free music swapping service succumbed in 2001 to the legal entanglements of copyright. Vendors like iTunes, legally picking up Napster’s dropped torch in pay-to-download services, are faced with a singular problem. As long as .mp3 was the currency of grassroots users, it could avoid close scrutiny by critics regarding quality standards or best practices. Because users of the service also provided its content, and because Napster was so free it was libertarian, the concept of “standards” was anathema.5 Less than self-governing, it was little more than controlled chaos. New services delivering online music for pay cannot afford such freedom, when customers demand value.6 Held to even higher standards, as is perhaps
appropriate, some music libraries and archives have seen fit to use .mp3,
as well as other formats, to deliver audio files to academic audiences
online. And again, convenience rather than audio quality, the desire to
cater to an increasingly online audience, appears to be a major motivating
factor (although not always). Here the quality stakes may be a little
higher, but as we will see, in the context of online music providers,
quality is a matter of perspective, and can be measured in many ways.
In assaying quality in the delivery of online music, to see how providers
are meeting the challenges of their audiences for worthwhile cultural
material, we must take a thoughtful approach that goes beyond simple measurement
of the sound technology itself, and even beyond the more complicated measurement
of convenience. As important as these factors are, this study of quality
extends to selection and uniqueness of the materials in the archive or
repository, authenticity of the material as delivered, and the trust and
expectations of the client population. NOTES
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