What Makes a Good Recording? Page 4
Another rather abtruse aspect of recorded sound, this pertains to the recording's freedom of strain or irritation. Steve Weiman of Pro Musica (an Urbana, IL dealer) has found that most listeners can detect the difference, not so much on the basis of conscious aural cues as by what the sound does to their muscle set. Irritating sounds tend to cause involuntary muscle tension; easy sound allows relaxation while listening.
This means freedom from distracting extramusical noises, which can range from the rumblings of air conditioners or nearby traffic to hum and hiss introduced by the recording/reproducing equipment. Different people differ in their tolerance to certain kinds of noises, but the most obtrusive are usually the random variety such as traffic or audience noises. Tape hiss, for which there is little excuse in these days of effective noise reduction (dbx, for example), can be raised from an almost-subliminal rushing to an irksome hissing by upper-range frequency-response peaks in the transducers.
Many professional recording engineers are, irrationally, far less tolerant of noise than they are of any other aspects of recorded sound. Some environmental noise is almost inevitable in any recording made before an audience, but tends to be less distracting to a listener familiar with the live-performance experience than to one who listens mainly to studio-made recordings.
14. Dynamic Range.
Not to be confused with signal/noise ratio, dynamic range is the span of volume levels from the softest to the loudest produced by a sound source. Although maximum volume levels for a full symphony orchestra have been cited as high as 120dB (approaching the threshold of pain), most observers now agree that 100dB is a more reasonable figure. Since the softest instrumental sounds are around 25dB in level, this means that the dynamic range of a full orchestra is around 75dB. (Signal/noise ratio, on the other hand, is the range between the loudest recorded passage and the recording medium's background noise. It should be at least 5dB lower than the dynamic range's bottom.)
It is quite possible to tape-record, without noise reduction, the full dynamic range of a large orchestra, but some hiss will be audible at listening levels approaching the originals. Dolby or dbx noise reduction will eliminate most of this. Volume compression—"gain riding"—is thus rarely necessary when recording with a two-mike pickup, even when "accent mikes" must be used. Balances and maximum recording level should be set beforehand and then left strictly alone. Only when recording pop groups, or closely-miked singers, is constant balance and level adjustment needed, and the word then is subtlety; the manipulations should not call attention to themselves unless that is their specific intent.
A disc, for various reasons, cannot accommodate as wide a dynamic range as an original tape, but again there should be as little awareness as possible of the volume compression. Restricted dynamic range has the effect of reducing surface noise (because signal levels never get down to near the background noise), but it tends to strip choral and symphonic music of its emotional impact. As a matter of fact, few things are as frustrating to classical-music listeners as a crescendo which builds towards a climax, then "crests out" before it gets there. One technique for avoiding this—and one that more commercial recording companies should consider—is to have the conductor raise the level of the quietest passages, while allowing crescendos to go to full volume. This effectively holds dynamics to within a practical range without putting a cap on the crescendos.
15. The Gestalt.
Again, this is directed at listeners familiar with live music. Does the recording convey the feel of a live musical experience, or doesn't it? If it doesn't, can it be high fidelity?
Finally, was the performance worth recording in the first place? A fantastic recording may be able to sustain itself for a few listenings, but even the best recording soon palls if the musical execution was sloppy, eccentric, or—worst of all—just downright dull. (How many of those supersound Telarcs do you listen to for the enjoyment of the music?) Fortunately, there are few performing groups bad enough that they can't turn in an occasional hair-raising performance, but you may have to record a whole season of indifferent performances before it happens. But when it does, you'll have a tape to treasure.