Sunday, February 05, 2006

hi-fi dummed down

Everything is black and white these days: Right and wrong, good and evil, for us or against us [by the way - we’re against you George]. Whatever happened to the grey areas: to subtlety, to the implicit, to ambiguity, to the transitory? Not everything can be deconstructed, quantified, referenced and categorised – least of all, music.

We could be forgiven for overlooking this annoying anomaly of the contemporary world when music industry professionals present us with a simple choice between lossy and lossless audio. The terms themselves are clear enough – insofar as they describe types of audio data compression. But the fact that they make no mention of the quality of the original recording can be misleading. As far as I can tell, iTunes files are limited to 128Kbit/sec, which they claim to be ”high-quality format that rivals CD quality”! Not much of a rival in my estimation – variable bit rate or not. To compress these files with a lossless encoder saves nothing, when 90% of the data from the original recording has already been jettisoned.

The name Compact Disc doesn’t merely describe a format, or data carrier, it also defines a clear standard of quality: at least the commercially available (Red Book) CD does. Typically, Apple (and it is not alone in doing so) suggests that iTunes makes it wonderfully easy to create your own custom music CD. Well, what they are describing here is not a CD in any qualitative sense, but as the public, quite reasonably associates the carrier with content; I think that such claims are misleading.

For the last decade and more, classical engineers have encoded their recordings at 20, and later at 24bit resolution – presenting a data stream of more than 2000Kbits/second, a quality only available commercially on a comparatively limited number of HDCDs and DVDAs. This chasm between state-of-the-art Hi-fi and what the public seem to be prepared to accept [in the name of portability] leaves the industry professionals in an invidious position: are we to continue making recordings at the highest possible quality, or follow the market trend, and record in lo-resolution?

Such an enquiry deserves to be left in rhetorical limbo but it does pose another question: what actually is contained in all that apparently redundant data? It’s all audio information after all. We’re told that it’s a pile of stuff of no real interest that we probably can’t hear anyway. I for one don’t believe that it’s quite so easy to define what we can and cannot hear. Besides, I find it extraordinary that less than 20 years ago not only hi-fi enthusiasts, but music lovers in general, were embroiled in heated debates about the relative merits of vinyl and CD. It wasn’t an esoteric debate either; the exclusive preserve of woolly-bearded audiophiles, but was of concern to everyone who wanted to ensure that an unscrupulous industry shouldn’t fob them off with a substandard product.

As Andrew Dickson noted in the Guardian, "Classical's not dead - it's discerning. Fans aren't uncooperative - they're uncared-for".

Classical music is more dependent on hi-fidelity than popular music for the simple reason that it requires a much wider dynamic range to capture effectively both the nuances of low-level ambient sound and the blazing fortissimo of a full symphony orchestra for example. Dynamic range refers to the difference between the softest and loudest sounds that a system can reproduce.

A broad dynamic range is not a prerequisite of most popular music forms for a number of reasons. Consequently, it is comparatively common to employ audio compression techniques to reduce or compress recorded sound. Audio compression is a delicate craft used to reduce the range in decibels between the loudest and softest audio signals. The sound of a whispering voice, for example, depends less on the absolute sound pressure level than on the character of the sound. It is quite usual to hear a very soft voice quite clearly above an entire rock band [Think of Moorcheba for example]. This is obviously not a natural acoustic phenomenon but the crafty work of audio compression. Its effect is to render popular music quite effectively within a limited dynamic range, thereby allowing us to appreciate the full range of softly spoken lyrics and full-bloodied screams without needing to make continual adjustments to the volume control. It also allows sound engineers to balance the very different natural sound levels of soft acoustic instruments with much louder electronic instruments.

Many of the elements which comprise modern popular music are electronic but even those which originate in acoustic sound become heavily stylised in the production process; acoustic instruments and voices are close miked to exclude acoustic reflections or reverberation and recorded sounds are often treated with special effects or given an unnaturally liberal coating of artificial reverb to enhance the raw, natural sound. Indeed, it is rarely the intention for popular music forms to even attempt to re-create a real acoustic. Moreover, audio compression has the added benefit of facilitating listening in the car, on portable players, and in noisy environments without undue disruption from background noise, and it makes it much easier to data compress the resultant audio with little sacrifice to the sonic fidelity.

The objectives of classical music recording differ from those of popular music recording in its attempt to capture and reproduce the experience of listening to music in a real acoustic space. [Artificial reverberation and other effects are used only to enhance the sense of reality or to try to re-create the concert hall experience.] Audio compression is not an effective solution because the intension is, as far as possible, to preserve the illusion of listening in a real acoustic space – or to capture the true essence of a live performance. Rather than making soft sounds louder we need to hear, and feel the difference between soft and loud – the full dynamic range of natural acoustic music.

These are not easily quantifiable qualities to capture or reproduce but if we are to improve the quality of recorded music we must continue to forge ahead with technological developments and to pass these on to the public: the alternative path of least resistance leads only to mediocrity.

1 Comments:

Blogger Pliable said...

Guthry - very interesting post.

See this link for a related article.

Tuesday, February 07, 2006 12:37:00 pm  

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