Philosophical and Pragmatic
Approaches to Stereo
The first three chapters have focused on
the various physiological, acoustical, and psychoacoustic
parameters that form the basis of stereophonic perception.
The technical procedures employed to produce today’s
stereo sound recording and reproduction process will be
discussed in subsequent chapters. All of these are tangible
elements involved in the creating the stereophonic illusion
and all are solidly grounded on scientific principles of
physics, acoustics, and biophysics.
Before any recording project can begin, however, certain fundamental decisions need to be made — decisions that will indicate the format, style, and even the procedures implemented during the recording process. Some of these decisions are dictated by the content or style of the subject to be conveyed, for example: music, speech, sound effects, etc. Other, more pragmatic factors considered at this stage include: whether the recording/reproduction process is intended to be solely an auditory experience, or will it combine sound with picture; the medium of the recording — commercial record release, radio or television broadcast, film, etc.; the mode of the project (entertainment, documentary, sports or news, etc.); and the anticipated reproduction or listening environment.
These fundamental decisions will determine how a recording project is to proceed, and many of them will be based on more intangible factors such as mood, feeling, and intuition than on scientific fact. Thus science and philosophy must go hand in hand in the creation of the stereo illusion.
All writers know that for any idea to be
communicated effectively The Five W’s should be
addressed: Who, What, When, Where, and Why. These five
considerations are equally important to the process of
making a recording. After all, sound recording is really
just another medium of communication — a means of
expressing an idea aurally rather than visually.
• Who is the listener? Is he/she
experienced in the subject of the recording? Is he/she a
“critical” or a “casual” listener?
• What is the medium? Is it a purely auditory one such as a cassette, compact disc, or the radio, or does it also involve pictures, such as film or television, multi-media, or DVD?
• When is he/she listening? Does the listening experience occur in the background or foreground of the listener’s attention?
• Where is the listening environment? Is it at home, at work, in an elevator, a theatre, while jogging, or in a car?
• Why is he/she listening? Is it for the pleasure of the experience, for information content, or simply for entertainment?
The answers to each of these questions
contribute significantly to the determination of how the
recording should proceed. Some factors can be
complementary, while others prove to be mutually exclusive.
The technical procedures employed, however, must be
compatible with all of these dictates. A producer even
might decide that more than one answer is appropriate to
each of the questions, possibly forcing a compromise
between various technical procedures.
To initiate the decision-making process,
the flavor of the recording first must be determined. This
“flavor” establishes the essential listening
experience that the producer, performer, and/or engineer
wants to convey to the listener. A recording is, by its
very nature, an artificial substitute for a
“live” experience — reality — and
can never be expected to equal the essential qualities
inherent in “being there.” The best any
recording can attain is a reasonable simulation of the live
experience; this simulation can be derived from two
related, although nonetheless quite different,
philosophical approaches to the recording process:
“Recreative” and “Creative.”
As the term “recreative” implies, this philosophy of recording intends to recreate a sonic experience for listeners in their own environment. The purpose is to make listeners feel that they are listening to a real event — something that actually happened, or could have happened — that has been transferred in time and/or space and transported into their presence via the recording process. This requires that all sense of the event’s realism must be captured and retained, so that listeners will feel as though they are participants at the event. Concerts, sporting events, news and documentaries are among the sonic events most appropriate to this recording philosophy.
Technical procedures for recreative recordings generally involve what are sometimes called “purist” microphone techniques (as will be discussed in Chapters Five, Six, Seven, and Nine) and uncomplicated recording methods to try to maintain the original ambience of the sonic space. These generally offer minimal alteration of the sonic perspective of the original event.
a New Event
“Creative” recording brings to
the listener an experience which never happened in
“real time,” but which the creators of the
sonic illusion would like to have happened. As before, the
intent is to make listeners participants at this sonic
event — even though this might be impossible to
achieve in the “real world.”
When creating a listening experience, applicable recording techniques allow considerably more experimentation, so that multi-microphone, multi-track procedures are more commonly utilized. Significant signal processing, synthesis, and artificial ambience are also employed to create a new, unique listening experience.
Some believe that these two approaches to expressing a sonic image — “Creative” or “Recreative” — are one and the same. This stems from the concept that the two are merely alternate means of observing an event and conveying its essence. The fundamental belief here is that the illusion can never equal the reality, because the only true reality is being there. In the context of recorded sound, however, reality is what you make of it.
The listener’s aural
“viewpoint” of the recording also can be
described by two contrasting sonic perspectives, which are
often called “You Are There” or “They Are
Here” (In this context, “you” refers to
the listener and “they” are the performers.)
When considering the listener’s perspective, the
differences between the approaches are more distinct than
the styles of creating a listening experience.
With “You Are There,” the intent is to generate an aural perspective which will transport the listeners into the same sonic environment as the event — to put the listeners into the audience, as it were. This approach is appropriate to almost any form of real sonic event, and lends itself particularly well to concerts, certain sporting events, dramatic or documentary presentations, environmental scenes, and the like.
On the other hand, “They Are Here,” as the name implies, attempts to bring the sonic event directly to the listener, and reproduce it in the listening environment. This approach is only plausible when the sonic “illusion” could logically be happening in this listening space. Hence, a major league ball game, large symphony orchestra, or recreation of “the Battle of the Bulge” would not be convincing, whereas a ping-pong match, a string quartet, or even a fist fight between two individuals might be.
“Two by Two” Matrix
The style of the reproduction can be
correlated with the viewpoint by placing them both into a
simple two-by-two matrix. If the top is labeled according
to philosophy and the sides according to perspective, it is
possible to derive four distinct approaches to the
recording and reproduction of a sonic experience. These
prove to be the logical result of the experience itself.
Both “You Are There” and
“They Are Here” recordings can be either
recreative or creative, depending on the sonic illusion
desired. The various technical means to accomplish these
styles can differ from one to another, which can be shown
by expanding the contents of the matrix to include some of
the relevant production techniques employed for each
approach. (Table 4-2)
The matrix implies that although there are
four initial directions a recording project can pursue,
within each are several “alternate routes”
which the producer or engineer also could follow. Once the
primary course has been determined, however, it should be
followed to its final destination. Sudden or abrupt
deviations from the chosen course might distract the
listener or lead to confusion — whether conscious or
subliminal — and thereby destroy the illusion. If the
listener becomes aware of the techniques employed to make
the recording, the program content will be pushed into the
background, rather than remain the focus of attention.
(Similarly, in the theatre, if the lighting effects or
staging draw the attention of the viewer away from the
story line, the essence of the play will be lost.)
Various technical constraints inherent to
the recording and reproduction medium also play an
important role when determining the processes to be used.
These considerations are not only the practical limitations
of the recording format (such as amplitude, dynamics,
phase, spectrum, and distortion), but also such factors as
the number of transmission channels, the placement of
loudspeakers in the listening environment, etc.
The amplitude limitation relates to the
absolute signal level inherent with the recording and
playback medium. Recording techniques intended for digital
audio production allow significantly greater freedom of
choice to the recording engineer than techniques used for
cassette or AM radio broadcast, where the signal level and
dynamic range are significantly more restricted.
Related to amplitude, the dynamic range of
a recording defines the extremes between loud and soft.
Like the absolute limit on amplitude, these extremes also
must be considered in context with both the sonic material
and the listening environment. For a recording to equal the
impact of a live concert, for example, the playback must be
at a sound pressure level near to what the listener would
experience in the concert hall. This has obvious
limitations in the practical world where the problems of
home playback equipment, consideration for the neighbors,
and other factors will restrict the playback volume to a
more conservative level. (This relates back to the where
and when discussed under “The Five W’s.”)
Nonetheless, a recording must be able to preserve the
impression — even if not the full extent — of
the dynamic range of the original, or the emotional impact
will be diminished. After all, a full symphony orchestra, a
heavy metal band, or even a competent singer can easily
overpower the acoustical capacities of a small apartment.
In Chapter Two, listening cues exhibiting
interchannel amplitude and time-of-arrival
phase) differences between the
two stereo channels were shown to be crucial to determining
our perception of stereo space throughout the entire
frequency spectrum. Thus, when considering the integrity of
the stereo image, a critical technical factor is phase
coherency between the channels. If the production
introduces contradictions between the amplitude and phase
cues in the stereo signal, serious image confusion could
result. Therefore it is of primary importance to retain
consistent amplitude and coherent phase response throughout
the entire recording/reproduction process, regardless of
the ultimate medium of distribution.
Although relative amplitude, spectrum, and dynamic range all can be compromised to some degree without causing serious deterioration of the stereo image, improper attention to phase coherency during the original recording process will produce a flawed recording from the outset, which cannot be corrected later. Therefore, the implementation of proper microphone techniques is crucial during the original recording stages, and these must be chosen to be complementary to the style of the recording and the demands of the distribution medium.
Spectrum is a technical term which
describes the texture of the waveform of all individual
sounds — defining their “sonic identity.”
Timbre is another, more musical name for spectrum. Although
the two terms are not identical (spectrum represents the
physical attributes of a sound, while timbre generally
refers to the more subjective perceptions of these
attributes), they are closely related because the
preservation of spectrum is essential to the accurate
reproduction of timbre. Throughout the recording and
reproduction process, careful preservation of the spectral
integrity of the sound is necessary to maintain the proper
illusion for the listener.
Distortion is the primary enemy of
spectrum because distortion generates unwanted alterations
to the sonic fidelity of the audio chain. It can affect any
or all of the previous technical factors, and its insidious
effects can be introduced anywhere in the long progress
from performance to listener.
Distortion can take two forms: linear or nonlinear. Linear distortion simply produces changes in the amplitude and phase response of the audio signal, but without adding anything else to it. Nonlinear distortion, however, creates new, unwanted components and adds them to the audio signal. These components can be either harmonically or non-harmonically related to the original signal, and are quite audible even at relatively low levels compared to the original signal. Thus, nonlinear distortion is generally considered much more annoying to the listener than linear distortion.
Although these technical considerations are not inherently part of the philosophy of the recording process, they must, nonetheless, be considered during the earliest planning stages because they interact with the philosophical factors. A comparison of the technical parameters with the various distribution formats can be shown by placing them into two columns, as in Table 4-3. (Please understand, however, that these are not meant to imply directly parallel comparisons.)
Each of the different recording formats
listed in Table 4-3 imposes its own technical limitations
on the recording/reproduction process. As an example, the
cassette format places greater constraints on the recording
process than does a compact disc or even a phonograph
record. All technical parameters — amplitude, phase
response, dynamic range, distortion, and spectral content
— have fairly narrow limits and should be considered
carefully when producing an original recording intended
specifically for cassette distribution.
However, if the same recording is to be released as a compact disc (a medium which does not pose these same restrictions) should the original recording be compromised for the sake of the cassette? Of course not. The proper procedure is to make the initial recording suitable for the compact disc and then use this full range recording to produce another, more controlled master suitable for cassette duplication. The rule of downward — or upward — compatibility is to preserve the absolute integrity of the original material as far into the recording/reproduction process as possible.
A similar comparison can be drawn when considering, for example, a compact disc recording which will subsequently be broadcast. Usually, the constraints necessitated by the broadcast medium are imposed by the radio or television facility itself, whose signal chain incorporates special signal processing devices to restrict dynamic range, spectrum, etc. With many radio stations, such manipulation of the original program signal is determined as much or more by their own “on-air sound” (philosophical considerations) as by fundamental technical constraints.
Next, suppose a recording is to be made by the broadcast facility’s own production staff, perhaps initially for air, but reserving the option for subsequent release as a compact disc or other format. Should the recording be made preserving full spectrum, with maximum separation and dynamic range, or should the recording team constrain these factors to suit the limitations of the broadcast medium or the station’s particular “sound”? Ultimately, this decision will be made by the program’s producer, who might choose to tailor the original recording to suit the station’s particular sound, thereby limiting further use of the material. Alternatively, he/she could retain full options for future use of the recording and leave any technical constraints subsequently in the hands of the broadcast engineer. Both attitudes are valid, but the decision must be made at the outset.
and Visual Images
When assessing the impact of television on
the dwindling radio audience, someone once quipped:
“Yes… but radio has better pictures.”
While this implies the importance of the listener’s
imagination, this also is a direct reference to the concept
of the Sonic Illusion. The point is that the visual images
presented by television (or film) dictate to us precisely
what we, the viewer, will see, and therefore constrain our
When producing sound with pictures (television or film) severe restraints are placed on the sound department to maintain a sonic perspective that will complement the visual image. (Chapter Thirteen discusses more fully the various perspectives available for sound with pictures.) If the sound editor wishes to withhold editorial decision over the sonic image until the picture has been cut, this dictates certain microphone and recording techniques which can afford this degree of flexibility during the rerecording mix.
The introduction of visual images introduces media-imposed restraints on the purely audio component of the program, because the pictures dictate just what the sonic perspective must be. The recording engineer is no longer free to create an autonomous sonic image. “You Are There” becomes the only possible attitude, and you, the listener, are limited to being a spectator of the event, rather than a participant.
“Law of Compromises”
It is important to reemphasize that the
basic approach to making a stereo recording must be decided
at the outset of the project, and this will be determined
by the several, often competing, technical and
philosophical factors involved. This decision process
acknowledges the Law of Compromise inherent throughout the
world of audio.
This law, although not written anywhere is universally imposed nonetheless. It dictates that any decision with regard to the production or reproduction of a recorded experience must result from a choice among compromises. Simply, this means that what is best for one set of circumstances likely may sacrifice others. It is the charge of the producer to select from among these compromises those that will be the most beneficial — or, stated another way, the least damaging — to the final product. Although this may seem a rather cynical viewpoint, it is merely simple pragmatism.
In the end, the choice is between illusion or reality… you can’t have both.