Lissajous Figure
A two-dimensional visual pattern produced by the interaction of two independent signals, each controlling the amplitude of one display axis. Used in the Stereo Goniometer and Stereo Vectorscope
Search
Found 26667 results
To find the exact phrase, put the words in quotes or join them together with a plus sign e.g. live+recording or "live recording".
To find, say, all live recording articles that mention Avid, enter: live+recording +avid - and use sidebar filters to narrow down searches further.
ILD
The difference in loudness or intensity of a sound wave reaching the left and right ears. In real life this is caused by diffraction of sound around the head at high-frequencies (above about 700Hz), causing a 'sound shadow' for the more distant ear. The brain uses the inter-aural level difference as a means of identifying the location of a sound source which will be louder on the side of the closer ear. See also ITD
ITD
The difference in the arrival time of a sound wave reaching the left and right ears. In real life this is caused by the extra distance the sound wave has to travel around the head, resulting in a detectable phase shift for frequencies below about 700Hz. The brain uses the inter-aural time difference as a means of identifying the location of a sound source which will be earlier on the side of the closer ear. See also ILD
Schneider Disc
A stereo microphone device used primarily for capturing binaural stereo and a variation on the OSS technique. Similar to the Jecklin disc, the Schneider disc comprises a circular baffle of 30cm diameter with acoustic absorption material on both surfaces supplemented with a 12cm foam-covered sphere at the centre of the disc to better approximate the acoustic characteristics of the human head. Omni-directional microphones are placed on either side with a roughly 16.5cm spacing and angled outwards at 20 degrees.
Intensity Stereo
The name given by Alan Blumlein to a stereo signal comprising only amplitude differences between the two channels. It can be created by using a pan–pot in a mixing console, or with a coincident (X-Y) microphones.
Hybrid Stereo Array
A stereo microphone array designed to extract the most attractive qualities associated with both spaced-omni (A-B) and coincident (X-Y) arrays. Inter-channel level differences are captured by angling directional microphones outwards, and inter-channel time differences are obtained by spacing the microphone capsules apart. In practice, some of the imaging accuracy associated with coincident techniques is sacrificed for the much greater sense of spaciousness associated with spaced-omni techniques. Popular hybrid arrays include ORTF, NOS, DIN, EBS, RAI and Gerzon.
Hole-In-The-Middle Stereo
An effect where the stereo sound appears to ‘puddle’ near the two loudspeakers without creating a continuous soundstage between them. It commonly occurs if microphones in a stereo array are spaced too far apart.
Head Related Transfer Functions
(HRTFs) Parameters which describe a unique set of acoustic filters created by sound reflections from an individual’s head, shoulders, and pinnae which modify the sound waves entering the ear canal. These unique characteristics are learned to allow the brain to locate sound sources in the 3D space around the listener. Perceiving accurate sound placement from a binaural audio source relies very heavily on the material being processed accurately with an individual’s personal HRTFs.
Goniometer
A stereo audio vectorscope which displays the stereo sound image as a Lissajous Figure to assess the correlation and stereo width between channels, as revealed by the phase and amplitude relationships between the two channels.
The two audio channels are plotted on diagonal axes such that a left-only signal is shown as a diagonal line from top-left to bottom-right, while a right-only signal runs from top-right to bottom-left. An identical signal on both channels (dual-mono) results in a thin vertical line, while identical signals in opposite polarity create a thin horizontal line. Normal stereo creates the appearance of a circular tangled ‘ball of string’.
Gerzon Stereo Microphone Array
A near-coincident stereo microphone array described in detail by British audio engineer Michael Gerzon (1945 – 1996) but also credited to Tony Faulkner. It comprises a pair of cardioid microphones with capsules spaced 5cm apart at a mutual angle of 120°. The resulting SRA is 130 degrees. This technique captures both time and level differences between channels, and is comparable to similar techniques such as ORTF, RAI, DIN, NOS and others, but with a noticeably smaller spacing and wider mutual angle. It is often used with a shuffling process to enhance the sense of spaciousness at low frequencies.
FantaSound
A set of pioneering technologies developed by the Walt Disney Studios in the late 1930s for the film Fantasia. It was the first commercial surround sound system, which pioneered the use of pan-pots for sound positioning, multitrack recording, overdubbing, click tracks for synchronisation, control tracks for automatic gain control, and more.
EBS Stereo Mic Array
An eponymously named near-spaced stereo microphone system developed by Eberhard SengPiel. It comprises a pair of cardioid microphones with capsules spaced 25cm apart at a mutual angle of 90°. The resulting SRA is 90 degrees. This technique captures both time and level differences between channels, and is comparable to similar techniques such as ORTF, RAI, DIN, NOS and others.
Dual-Mono
Identical audio content carried in both the left and right channels of a stereo system (ie. panned centre), resulting in a phantom centre sound image.
Fletcher, Dr Harvey
Dr Harvey Fletcher (1884 – 1981) was an American physicist working for Bell Laboratories on the development of Stereophonic Sound, amongst other things, in the early 1930s. He was a contemporary of Alan Blumlein but was developing stereo techniques entirely independently.
Double Mid-Sides Array
An extension of the Mid-Sides microphone concept in which a second Mid microphone is added to the array, but facing directly backwards. This system requires only three audio channels, but can be decoded to create five channels as the shared Sides mic is used with the rearward Mid mic to generate rear left and rear right signals suitable for surround sound applications. Sometimes referred to as the DMS format and employed where a compact surround-sound mic array is required.
DIN Stereo Microphone array
An acronym for a German standards organisation founded in 1917: Deutsches Institut für Normung. Amongst many audio standards created by this organisation, the DIN stereo microphone array comprises a pair of near-spaced cardioid microphones with capsules spaced 20cm apart at a mutual angle of 90°. The resulting SRA is 101 degrees. This technique captures both time and level differences between channels, and is comparable to similar techniques such as ORTF, RAI, EBS, NOS, and others.
Curtain of Sound
An approach to capturing and reproducing stereophonic sound developed by Dr Harvey Fletcher (of Bell Labs in America) in the early 1930s. A multiplicity of microphones arrayed in front of a large ensemble sample the audio wavefront at different points in space. Each microphone is connected to a corresponding loudspeaker in front of the audience to recreate the same wavefronts. Although effective, this technique was deemed highly impractical at the time, and it evolved through simplification into various spaced-omni microphone techniques.
Cross-Feed Matrix
A technology often employed in headphone monitoring to recreate the acoustic crosstalk between ears which naturally occurs with loudspeaker listening, but which is normally excluded by headphones. A portion of the signal from each channel is fed into the opposite channel with equalisation and a short delay.