Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
  • H04S3/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R5/00—Stereophonic arrangements
  • H04R5/033—Headphones for stereophonic communication
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
  • H04S3/02—Systems employing more than two channels, e.g. quadraphonic of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S2400/00—Details of stereophonic systems covered by H04S but not provided for in its groups
  • H04S2400/01—Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S2420/00—Techniques used stereophonic systems covered by H04S but not provided for in its groups
  • H04S2420/01—Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]

Definitions

• the present invention relates to the field of spacialized sound spatialization of sound signals, integrating in particular a room effect, particularly in the field of transaural techniques.
• the term "binaural” refers to the reproduction on a stereophonic headphones, or a pair of headphones or a pair of speakers, a sound signal with nevertheless spatialization effects.
• the invention is however not limited to the aforementioned technique and applies, in particular, to techniques derived from "binaural” such as "transaural" (commercial name) restitution techniques, that is to say on remote loudspeakers, installed for example in a concert hall or cinema with a multi-point sound system.
• a specific application of the invention is, for example, the enrichment of audio content broadcast by a pair of speakers to immerse a listener in a spatialized sound scene, including in particular a room effect or outdoor space.
• the state of the art defines a transfer function, or filter, of a sound signal between a position of a sound source in the space and the two ears of a listener.
• the acoustic transfer function of the aforementioned head is designated HRTF for "IHead Related Transfer Function” in English in its form. frequency and HRIR for "JHead Related Impulse Response” in English in its temporal form.
• HRTF for one direction of space, we finally get two HRTFs: one for the right ear and one for the left ear.
• the binaural technique consists in applying such acoustic transfer functions of the head to monophonic audio signals, in order to obtain a stereophonic signal which makes it possible, when listening to headphones, to have the feeling that the sources sounds come from a particular direction of space.
• the signal from the right ear is obtained by filtering the monophonic signal by the HRTF of the right ear and the left ear signal is obtained by filtering the same monophonic signal by the HRTF of the left ear.
• FIG. 1 represents a general block diagram of the installation intended for the phase of constructing the pulse signal database.
• FIG. 2 represents a schematic view of the installation for acquiring pulse signals
• the method according to the invention comprises a first processing (1) of producing a database of pulse signals from the acquisition of acoustic signals in a plurality of physical spaces, by
• the method consists in applying a succession of
• the method comprises a preliminary stage (2) of constructing a signal N.i from the stereo signal
• This stereo signal can then be broadcast by a pair of standard loudspeakers, to restore a spatialized sound environment corresponding to the space that has been used to produce the impulse response signals or a combination of such spaces.
• This step is replicated a plurality of times.
• impulses to be arranged in a physical space such as a concert hall, an open or closed place, a given room, a series of known loudspeakers (5 to 11; 17) associated with an amplifier (14), preference of recognized quality, as well as a microphone pair (12, 13) whose position relative to the speaker series (5 to 11; 17) is fixed for the series being acquired.
• Each of the speakers (5 to 11) is then successively applied to an original multifrequency signal using the amplifier (14).
• This original signal is for example a sequence of a duration of between 10 and 90 seconds, with a frequency variation in the sound spectrum.
• This signal is for example a linear variation between 20 Hz and 20 kHz, or any signal covering the entire spectrum of the enclosure.
• the sound signal produced by the active speaker is picked up by the microphone torque (12, 13) and produces a recorded stereo signal. From this signal, 96 kHz sampling is carried out in a known manner and at a
• This step is reproduced for each of the speakers (5 to 11) of the series, then for different physical spaces where a series of identical or identical speakers is re-inserted.
• This first step leads to the construction of a database of stereo impulse responses.
• This step makes it possible to construct a spatial stereo audio signal from a multichannel signal N.i
• This step consists in selecting in the database formed during the initial step N + i impulse responses.
• the selection will consist in associating with each of the N + 1 signals one of the impulse responses of said database, ensuring that the acquisition position in the space of the impulse response corresponds to the position in the space of the channel with which it is associated.
• a convolution processing is applied to calculate a stereo spatialized signal cut S sG and S sD .
• channel equalization is performed to improve the dynamics of the signals.
• the final step is to recombine the signals to build a right and left signal pair
• the channels are equalized to improve the dynamics of the two channels.
• Case of a stereo start signal increasing the number of channels and creating intermediate channels
• the signal to be spatialized is not of the Ni type but simply a stereo signal
• a step is taken intermediate consisting of building a signal Ni by phase extraction treatments between the left and right track, to build different new signals.
• This extraction by phase consists in producing a signal corresponding to a reconstructed central channel, by a processing consisting in adding the signal of the left channel with a signal of the straight line which is out of phase, for example in phase opposition.
• the left and right tracks are phase-shifted, with different phase-shift angles, and the out-of-phase signal pairs are added, with determined weights.
• frequency filters are applied to right and left signals when creating "reconstructed" channels, in order to increase signal dynamics and maintain high fidelity sound quality.
• FIG. 3 represents a schematic view of the reproduction installation, from a pair of actual speakers (17, 18).
• This pair of speakers (17, 18) receives a signal for simulating calculated speakers (20 to 27 and 30 to 37).
• the effective number of calculated speakers (20 to 27) corresponds to the number of physical speakers (5 to 11; 17) used for the production of the pulse signal database, or to the number of virtual speakers reconstructed by the method referred to above.
• Virtual speakers (30 to 37) are also created which produce a perception in the sound space of a combination of real neighboring speakers, to fill the sound holes.
• These virtual speakers are created by a modification of the signal supplying the neighboring real speakers.
• the signals are distributed according to their right, left or central component to produce a left signal (17) for the left speaker, and a right signal for the right speaker (18):
• the "right” signal corresponds to the addition of the calculated “right” signals (21, 22, 23) and virtual “right” signals (30, 31, 32), as well as the "central” signals calculated (20, 27) and virtual (33) with an amplitude weighting of 50%
• the "left" signal corresponds to the addition of the left calculated signals (24, 25, 26) and the left virtual signals (34, 35, 36), as well as the calculated central (20, 27) and virtual (33 ) with an amplitude weighting of 50%.
• This stereo signal is then applied to a conventional audio equipment, connected to a pair of speakers (18, 19), which will reproduce a spatialized sound environment corresponding to the sound environment of the installation that was used to build the base impulse signals, or a virtual sound environment corresponding to the combination of several original atmospheres, where appropriate enriched with virtual atmospheres.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Algebra (AREA)
• General Physics & Mathematics (AREA)
• Mathematical Analysis (AREA)
• Mathematical Optimization (AREA)
• Mathematical Physics (AREA)
• Pure & Applied Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Stereophonic System (AREA)

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• 2012
  • 2012-02-13 FR FR1251328A patent/FR2986932B1/fr active Active
• 2013
  • 2013-02-11 RU RU2014133066A patent/RU2639955C2/ru active
  • 2013-02-11 EP EP13710449.3A patent/EP2815589B1/fr active Active
  • 2013-02-11 CN CN201380009062.2A patent/CN104160722B/zh active Active
  • 2013-02-11 JP JP2014556128A patent/JP6421385B2/ja not_active Expired - Fee Related
  • 2013-02-11 BR BR112014019926A patent/BR112014019926A2/pt not_active Application Discontinuation
  • 2013-02-11 WO PCT/FR2013/050278 patent/WO2013121136A1/fr not_active Ceased
  • 2013-02-11 IN IN6776DEN2014 patent/IN2014DN06776A/en unknown
  • 2013-02-11 KR KR20147024937A patent/KR20140128412A/ko not_active Abandoned

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