EP0050100A2 - Einrichtung zur räumlichen Aufnahme von Schall - Google Patents

Einrichtung zur räumlichen Aufnahme von Schall Download PDF

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Publication number
EP0050100A2
EP0050100A2 EP81830187A EP81830187A EP0050100A2 EP 0050100 A2 EP0050100 A2 EP 0050100A2 EP 81830187 A EP81830187 A EP 81830187A EP 81830187 A EP81830187 A EP 81830187A EP 0050100 A2 EP0050100 A2 EP 0050100A2
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EP
European Patent Office
Prior art keywords
cavity
sounds
auditory meatus
spatial
sound
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Application number
EP81830187A
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English (en)
French (fr)
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EP0050100A3 (de
Inventor
Hugo Zuccarelli
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Individual
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Individual
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Publication date
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Publication of EP0050100A2 publication Critical patent/EP0050100A2/de
Publication of EP0050100A3 publication Critical patent/EP0050100A3/de
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R5/00—Stereophonic arrangements
    • H04R5/027—Spatial or constructional arrangements of microphones, e.g. in dummy heads

Definitions

  • This invention concerns a device for spatial codification of sounds which may be defined as 'holophonic' in analogy with holography.
  • the invention allows direct recording or transmission of stereophonic sounds; so as to give the listener effective spatial and true stereophonic dimension rather than a bidimensional one.
  • stereophonic recording was done by placing two or more microphones in strategic points and recording on a record or tape two separate tracks which are then reproduced through two strategically placed speakers.
  • Another existing device consists of an artificial head equipped with internal microphones placed in the base of the neck so as to obtain a limited and imperfect sound prospective which may furthermore only be appreciated by using ear phones.
  • the human ear may be considered as a system in which a stimulus enters and a sensation exits, and the auricle of the ear acts as a collector of sound energy, concentrating it in the meatus and sending it to the eardrum in the form of resonant pressures.
  • the present invention gives another interpretation of the way in which sound energy is transmitted to the hearing organ and, starting from this interpretation, develops a recording system which is able to give a true stereophonic perception of the sound transmitted.
  • an examination of the hearing organ shows that it must analyze information from sound sources using its own mechanism.
  • the hearing organ dynamically analyzes sound information by the sensorial effect of the entire body as well as by spatial codification through the auricles.
  • this organ only performs an instantaneous statistical analysis of the sound information, which thus also instantaneously gives the position of the sound source with respect-to the listener.
  • this mechanism of analysis has been found to conform to laser holography, that is, to holography of sound..
  • laser holography consists of the formation and photographic impression of a diffraction figure formed by two laser rays (that is, by coherent light) coming from the same source.
  • One of these is reflected in a mirror and impinges directly on the photographic plate, while the second directly illuminates an object and is then reflected by it.
  • the two rays hit the plate with different angles and optical paths and so interfere with one another.
  • This interference leads on the plate to a very complex pattern of light and shadow which however contains all the spatial information of the holo- graphed object.
  • Recomposition of the refraction pattern with an analogous technique gives rise to a spatial image of the object. Therefore, a person seeing this spatial image has the complete sensation of observing the original, not only its shape but also its volume.
  • interference patterns seem disordered, they contain a series of information like a hologram. Thus, this series of information can give the shape of the-reflecting surface of the obstacle. If an obstacle is shaped symmetrically, it will give a symmetric interference pattern. However, this pattern gives incomplete information since there-are two images possible, one re real one and one completely analogous but rotated 180°. Therefore, the real position of the wave source cannot be part of this information. For an asymmetric reflecting surface, however, there is one and only one possibility of spatial reconstruction. Of course, the interference pattern will also be asymmetric and will be unequivocal in that the exact position of the wave source may be determined. Note that as in laser holography, the interference pattern is a formation of points, each one of which contains the information of the entire hologram. That is , a suitably programmed computer could reconstruct the entire hologram with the information contained in only one of its points.
  • the auricle of the human ear is such a surface.
  • the ear is in itself the synthesis of perfection never before developed, a sublime and extremely precise work of engineering. Its morphological dimensions are such that it forms almost a complete spiral, up to half of the third quadrant before starting to decrease. Therefore, in light of the above discussion, the auricle of the ear shows total asymmetry; in front of a wave source of a given frequency both the ears and the head of the listener give rise to the interference patterns necessary for spatial analysis, but it is the auricle itself which gives the most valuable information.
  • the longer vertical dimension allows the auricle to spatially perceive low frequency waves (on the order of 1400 Hz), while the shorter horizontal dimension allows the perception of high frequencies up to 3400 Hz.
  • a holophonic recording system was developed characterized by the fact that it involves a microphonic device shaped like a human head, equipped with auricles and internal cavities which faithfully reproduce the shape of the auricle, the auditory meatus, the Eustachian tubes and the oral cavity, as well as a wig which serves to generate asymmetry for front-back discrimination and two microphones placed in cavity acting as auditory meatus, in the exact posi- ; tion and orientation as the eardrum and in communication in back with the cavities acting as Eustachian tubes.
  • the oral cavity is in communication with the outside.
  • the microphones have a cardioid-shaped membrane no smaller than 7mm.
  • the cavity acting as auditory meatus is in the shape of an elliptical section cylinder twisted on its axis so that the wall (which is behind the internal orefice) inclines gradually so as to become lower-back, while the upper part becomes upper-back.
  • the cavity acting as auditory meatus preferably has an average length along its axis of 24mm, the first eight of which are made of the same material as the auricle.
  • the other 16 have a covering layer of more rigid material, so as to simulate the fibro-cartilaginous (8mm) and the bony portions (16mm).
  • cords for the two microphones pass through the oral cavity and come out through the outside opening.
  • the two ears that are the basis of our auditory system enable us to distinguish the source of the sound. But the sound itself (for example, the violin) does not come from one point but rather a collection of points. Moreover, the room where we are, which reflects the sound generated by the violin, in turn generates a collection of sounds which are perceived by our hearing system to arise from a space outside the area of the primary sound source (in this case the violin).
  • the holophonic recording system involves a microphonic support 1 shaped like a human head.
  • This support is preferably made of plastic material like polystyrene and has two ears 2 with an auricle 3 which faithfully copies the auricle of a human ear.
  • Each auricle 3 has a cavity 4 shaped exactly like the auditory meatus, at the bottom of which a microphone 5 is placed in the same position and orientation as the eardrum of the ear.
  • the rear face of each microphone 5 is in free communication with a tubular cavity 6 which faithfully reproduces the shape of the Eustachian tubes.
  • These cavities 6 are in communication with a central cavity 7 which faithfully reproduces the shape of the oral cavity and which is in communication with the outside through a tubular cavity 8.
  • Auricles 5 and the first 8mm of the auditory meatus are preferably made of rubber, while the remaining 16mm has an interior layer of plaster or the like 11, to simulate respectively the fibro-cartilagenous and bony portions of the middle ear.
  • the top is covered with a wig 9 to generate the desired asymmetry front to back.
  • Wires 10 of the microphones come out of tubular cavity 6, enter central cavity 7 and go outside through tubular cavity 8.
  • the human ear and therefore the system according to this invention have in the meatus a sharp dilation 12 which acts like the muffler of an internal combustion engine.
  • Microphones 5 have a cardioid membrane no smaller than 7mm, preferably delineated by the external covering of the microphone which has an opening this shape.
  • Cavity 4 acting as the meatus has a section of an elliptical section cylinder with a torsion on its axis such that the wall in correspondence with the external orefice is anterior, inclining gradually so as to become lower front, while the posterior wall becomes upper rear. The flatter the former, the more highly convex is the latter.
  • reproduction of a magnetic tape recroding on a conventional stereo system allows the listener to mentally reproduce how the recording was made in a studio, independently of the hearing sense. In this way, even if two listeners are facing one another, they will have the front-back sensation in the exact sense in which they are arranged. It is interesting to observe that it is not necessary to put the acoustic boxes in a pre-fixed position, since their sound has already been codified and this information cannot be altered.
  • the critical measurements of the entire external auditory system are 20cm for the head (equal to a frequency of 450Hz) and 6cm for the ear (equal to a frequency of 1400Hz). Above these frequencies, anomalies are to be expected arising from the cancellation, due to the interference patterns created near the ear.
  • the frequency response curve of the human head is measured, it will correspond to that of the device according to this invention, as precisely as the anatomical characteristics are respected in its construction.
  • the curves traced with sounds coming from the sides of the device resemble the mean normal audiogram known to all who study physiological acoustics.
  • said curves show a striking drop corresponding to low and high frequencies and two resonance peaks at 2500Hz and 7500Hz, corresponding to the 1st and 3rd resonance frequency of the auditory system.
  • This negative aspect may be eliminated by cancelling the resonances in a known fashion with suitable filters and by using octave amplifiers for the missing low and high frequencies.
  • phase displacement of the harmonics with respect to the fundamental a dynamic analysis of a sound composed using this invention reveals a delay of some upper frequencies while the low frequencies remain stable on the oscillograph.
  • the speakers must be placed in strategic points so as to avoid sizeable modifications of the original phase'displacement.
  • phase codes during electro-acoustic, transduction, that is, to use acoustic boxes with phase correction or a single speaker of the extended range type.
  • the device according to this invention with spatial codification of sounds, may be used in the same way in direct transmissions in addition to recordings.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Stereophonic Arrangements (AREA)
  • Stereophonic System (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
EP81830187A 1980-10-09 1981-10-08 Einrichtung zur räumlichen Aufnahme von Schall Withdrawn EP0050100A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT8025248A IT8025248A0 (it) 1980-10-09 1980-10-09 Sistema di registrazione olofonico.
IT2524880 1980-10-09

Publications (2)

Publication Number Publication Date
EP0050100A2 true EP0050100A2 (de) 1982-04-21
EP0050100A3 EP0050100A3 (de) 1982-06-16

Family

ID=11216126

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81830187A Withdrawn EP0050100A3 (de) 1980-10-09 1981-10-08 Einrichtung zur räumlichen Aufnahme von Schall

Country Status (3)

Country Link
EP (1) EP0050100A3 (de)
JP (1) JPS5799097A (de)
IT (1) IT8025248A0 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4739513A (en) * 1984-05-31 1988-04-19 Pioneer Electronic Corporation Method and apparatus for measuring and correcting acoustic characteristic in sound field
US4741035A (en) * 1983-06-01 1988-04-26 Head Stereo Gmbh Wide band, low noise artificial head for transmission of aural phenomena
US5031216A (en) * 1986-10-06 1991-07-09 Akg Akustische U. Kino-Gerate Gesellschaft M.B.H. Device for stereophonic recording of sound events
EP0637188A1 (de) * 1993-07-27 1995-02-01 Central Research Laboratories Limited System für die Tonaufzeichnung
US5793873A (en) * 1996-07-07 1998-08-11 Visual Sound Limited Partnership Sound capturing method and device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2437373C3 (de) * 1974-08-02 1977-03-10 Polygram Gmbh, 2000 Hamburg Einrichtung zur Aufnahme von Schallsignalen unter Verwendung eines Kunstkopfes
JPS5312602A (en) * 1976-07-21 1978-02-04 Hitachi Ltd Dummy head

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4741035A (en) * 1983-06-01 1988-04-26 Head Stereo Gmbh Wide band, low noise artificial head for transmission of aural phenomena
US4739513A (en) * 1984-05-31 1988-04-19 Pioneer Electronic Corporation Method and apparatus for measuring and correcting acoustic characteristic in sound field
US5031216A (en) * 1986-10-06 1991-07-09 Akg Akustische U. Kino-Gerate Gesellschaft M.B.H. Device for stereophonic recording of sound events
EP0637188A1 (de) * 1993-07-27 1995-02-01 Central Research Laboratories Limited System für die Tonaufzeichnung
US5793873A (en) * 1996-07-07 1998-08-11 Visual Sound Limited Partnership Sound capturing method and device
US6714653B1 (en) 1996-07-07 2004-03-30 Douglas Peter Magyari Sound capturing method and device

Also Published As

Publication number Publication date
JPS5799097A (en) 1982-06-19
EP0050100A3 (de) 1982-06-16
JPH0474918B2 (de) 1992-11-27
IT8025248A0 (it) 1980-10-09

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