Stereo imaging
Encyclopedia
Stereo imaging is an audio
jargon
term used for the aspect of sound recording and reproduction
concerning spatial locations of the sound source(s), both laterally and in depth. An image is 'good' if the performers can be effortlessly located; 'bad' if there is no hope of doing so. A well-made stereo
recording, properly reproduced, can provide good imaging within the front quadrant
; a well-made Ambisonic
recording, properly reproduced, can offer good imaging all around the listener and even including height information.
For many listeners, good imaging adds markedly to the pleasure of reproduced music
. One may speculate that this is due to the evolution
ary importance to humans of knowing where sounds are coming from, and that imaging may therefore be more important than some purely esthetic considerations in satisfying the listener. Listeners do exist who have difficulty paying attention to the musical content of a recording if the imaging is not good.
The quality of the imaging arriving at the listener's ear depends on numerous factors, of which the most important is the original "miking", that is, the choice and arrangement of the recording microphones (where "choice" refers here not to the brand
s chosen, but to the size and shape of the microphone diaphragms
, and "arrangement" refers to microphone placement and orientation relative to other microphones). This is partly because miking simply affects imaging more than any other factor, and because, if the miking spoils the imaging, nothing later in the chain can recover it.
If miking is done well, then quality of imaging can be used to evaluate components in the record/playback chain (remembering that once the imaging is destroyed, it cannot be recovered).
It is worth noting that only a handful of recordings are miked for optimal imaging, and what usually passes for stereo, while being two-channel recording, is not true stereo because the imaging information is incoherent
.
Imaging is usually thought of in the context of recording with two or more channels, though single-channel recording may convey depth information convincingly.
Sound recording and reproduction
Sound recording and reproduction is an electrical or mechanical inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording...
jargon
Jargon
Jargon is terminology which is especially defined in relationship to a specific activity, profession, group, or event. The philosophe Condillac observed in 1782 that "Every science requires a special language because every science has its own ideas." As a rationalist member of the Enlightenment he...
term used for the aspect of sound recording and reproduction
Sound recording and reproduction
Sound recording and reproduction is an electrical or mechanical inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording...
concerning spatial locations of the sound source(s), both laterally and in depth. An image is 'good' if the performers can be effortlessly located; 'bad' if there is no hope of doing so. A well-made stereo
STEREO
STEREO is a solar observation mission. Two nearly identical spacecraft were launched into orbits that cause them to respectively pull farther ahead of and fall gradually behind the Earth...
recording, properly reproduced, can provide good imaging within the front quadrant
Circular sector
A circular sector or circle sector, is the portion of a disk enclosed by two radii and an arc, where the smaller area is known as the minor sector and the larger being the major sector. In the diagram, θ is the central angle in radians, r the radius of the circle, and L is the arc length of the...
; a well-made Ambisonic
Ambisonics
Ambisonics is a series of recording and replay techniques using multichannel mixing technology that can be used live or in the studio. By encoding and decoding sound information on a number of channels, a 2-dimensional or 3-dimensional sound field can be presented...
recording, properly reproduced, can offer good imaging all around the listener and even including height information.
For many listeners, good imaging adds markedly to the pleasure of reproduced music
Music
Music is an art form whose medium is sound and silence. Its common elements are pitch , rhythm , dynamics, and the sonic qualities of timbre and texture...
. One may speculate that this is due to the evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary importance to humans of knowing where sounds are coming from, and that imaging may therefore be more important than some purely esthetic considerations in satisfying the listener. Listeners do exist who have difficulty paying attention to the musical content of a recording if the imaging is not good.
The quality of the imaging arriving at the listener's ear depends on numerous factors, of which the most important is the original "miking", that is, the choice and arrangement of the recording microphones (where "choice" refers here not to the brand
Brand
The American Marketing Association defines a brand as a "Name, term, design, symbol, or any other feature that identifies one seller's good or service as distinct from those of other sellers."...
s chosen, but to the size and shape of the microphone diaphragms
Diaphragm (acoustics)
In the field of acoustics, a diaphragm is a transducer intended to faithfully inter-convert mechanical motion and sound. It is commonly constructed of a thin membrane or sheet of various materials. The varying air pressure of the sound waves imparts vibrations onto the diaphragm which can then be...
, and "arrangement" refers to microphone placement and orientation relative to other microphones). This is partly because miking simply affects imaging more than any other factor, and because, if the miking spoils the imaging, nothing later in the chain can recover it.
If miking is done well, then quality of imaging can be used to evaluate components in the record/playback chain (remembering that once the imaging is destroyed, it cannot be recovered).
It is worth noting that only a handful of recordings are miked for optimal imaging, and what usually passes for stereo, while being two-channel recording, is not true stereo because the imaging information is incoherent
Coherence (physics)
In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....
.
Imaging is usually thought of in the context of recording with two or more channels, though single-channel recording may convey depth information convincingly.
See also
- High fidelityHigh fidelityHigh fidelity—or hi-fi—reproduction is a term used by home stereo listeners and home audio enthusiasts to refer to high-quality reproduction of sound or images, to distinguish it from the poorer quality sound produced by inexpensive audio equipment...
- Phantom centerPhantom centerPhantom center refers to the way human ears detect the location of a sound; straight ahead, above, or behind the head. Since humans have one ear on each side of the head, sound in aforementioned locations creates an equal sensation in each ear. Thus, based only on hearing, the sound can be...
- Sound localizationSound localizationSound localization refers to a listener's ability to identify the location or origin of a detected sound in direction and distance. It may also refer to the methods in acoustical engineering to simulate the placement of an auditory cue in a virtual 3D space .The sound localization mechanisms of the...
- Sound stageSound stageIn common usage, a sound stage is a soundproof, hangar-like structure, building, or room, used for the production of theatrical filmmaking and television production, usually located on a secure movie studio property.-Overview:...
- WanderWanderIn telecommunication, wander are long-term low-frequency random variations of the significant instants of a digital signal from their ideal positions. Phase variations with a frequency content above 10 Hertz are considered jitter, while those with a frequency below 10 Hz are referred to as wander....