EP1212923B1 - Verfahren und anordnung zur erzeugung eines zweiten audiosignales von einem ersten audiosignal - Google Patents

Verfahren und anordnung zur erzeugung eines zweiten audiosignales von einem ersten audiosignal Download PDF

Info

Publication number
EP1212923B1
EP1212923B1 EP00956732A EP00956732A EP1212923B1 EP 1212923 B1 EP1212923 B1 EP 1212923B1 EP 00956732 A EP00956732 A EP 00956732A EP 00956732 A EP00956732 A EP 00956732A EP 1212923 B1 EP1212923 B1 EP 1212923B1
Authority
EP
European Patent Office
Prior art keywords
audio signal
delayed
gain
signal
audio
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP00956732A
Other languages
English (en)
French (fr)
Other versions
EP1212923A2 (de
Inventor
Michael 43 Nasmyth Street PERCY
Alastair Sibbald
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Creative Technology Ltd
Original Assignee
Central Research Laboratories Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Central Research Laboratories Ltd filed Critical Central Research Laboratories Ltd
Publication of EP1212923A2 publication Critical patent/EP1212923A2/de
Application granted granted Critical
Publication of EP1212923B1 publication Critical patent/EP1212923B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S5/00—Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation 

Definitions

  • This invention relates to the reproduction of 3D-sound from two-speaker stereo systems, headphones, and multi-speaker audio systems. It relates particularly, though not exclusively, to a method for the creation of one or more virtual sound sources simultaneously from a single, common sound signal which, nevertheless, can be discerned separately from one another by a listener in use.
  • the Haas (or Precedence) Effect [M B Gardner, J. Acoust. Soc. Am., 43, (6), pp.1243-1248 (1968)] is the phenomenon that the brain, when presented with several similar pieces of audio information at slightly differing times to process, uses only the first information to arrive from which to compute directional information. The brain then attributes the subsequent, similar information packets with the same directional information. The key to this is that the brain recognises signals which are related to one another (i.e. correlated), and processes them in a particular way.
  • This effect is also known under the names "law of the first wavefront”, “auditory suppression effect”, “first-arrival effect” and “threshold of extinction”, and it is used for the basis of sound reinforcement used in Public Address systems.
  • the relevance of the precedence effect here is that it can contribute to "spatial fusion", under particular circumstances, during the synthesis of virtual 3D-sound images.
  • the "Spatial Fusion” effect is not widely appreciated or known, and it is common both to loudspeaker and headphone listening. It occurs when synthesising several virtual sound sources from a single, common source, such that there is a significant common-mode content present in the left and right channels (and rear-left and rear-right channels in a four-speaker 3D-audio system).
  • Example 1 Primary signal + derived reverberation.
  • any signals which have been derived directly from another sound source (such as a [secondary] reverberation signal created from a primary source), are perceived to "combine” spatially with the primary signal if they are presented to the listener within a period of about 15 ms. Beyond this time period, they begin to be discernible as separate entities, in the form of an echo.
  • the effect of such spatial combination is to inhibit the secondary image and create an imprecise and vaguely positioned spatial image at the location of the primary sound source.
  • the HRTF processing decor relates the individual signals sufficiently such that the listener is able to distinguish between them, and hear them as individual sources, rather than "fuse” them spatially into apparently a single sound.
  • the HRTF processing decor decorrelates the individual signals sufficiently such that the listener is able to distinguish between them, and hear them as individual sources, rather than "fuse” them spatially into apparently a single sound.
  • the symmetry enhances any correlation between the individual sound sources, and the result is that the perceived sounds can become spatially "fused” together into one. For example, if it is required to "virtualise stereo" for headphone listening (i.e.
  • a line or area sound-emitter can be considered to be the sum of many individual elemental sound-sources which all possess differing amplitude and phase characteristics.
  • Dolby Pro-Logic system or Dolby Surround . It is characterised by the encoding of four channels of analogue audio into two channels of analogue audio, such that it can be recorded on to video tapes and DVDs (and also used for TV broadcast), from which the signals are decoded and used to drive four loudspeakers (left, centre, left-surround and right-surround), together with an optional sub-woofer.
  • the bandwidth limitations only allow a single rear-channel "surround” signal. If this signal was fed in parallel to both rear loudspeakers, the Precedence Effect would make the surround channel audio all appear to come from the nearest loudspeaker only.
  • the surround signal is fed directly to one of the rear speakers, but it is inverted before being sent to the other rear loudspeaker.
  • This is a crude way to decorrelate the signals being emitted from both surround speakers, but it assists the listeners to perceive sounds emanating from both loudspeakers, rather then just one, thus creating a more spacious experience.
  • 3D Positional Audio processing for computer games.
  • the signals In order to synthesise audio material bearing 3D-sound cues for the listener to perceive, the signals must be convolved with one or more appropriate HRTFs, and then delivered to the listener's ears in such a way that his or her own hearing processes do not interfere with the in-built 3D cues. This can be achieved either by listening through headphones, or via loudspeakers in conjunction with a suitable transaural crosstalk-cancellation scheme (as described in co-pending patent application GB9816059.1).
  • a suitable transaural crosstalk-cancellation scheme as described in co-pending patent application GB9816059.1
  • we recently devised a method for creating line and area virtual sound-sources GB9813290.5).
  • US 5,844,993 discloses use of a complementary comb filter pair to create a pair of rear channels from the single "surround" channel, and shows the first notch and peak features occurring at 100 Hz.
  • a signal can be decorrelated by means of comb-filtering, as is known in the prior art.
  • Figure 1 shows a simple comb filter, in which the source signal, S, is passed through a time-delay element, and an attenuator element, and then combined with the original signal, S.
  • the time-delay corresponds to one half a wavelength
  • the two combining waves are exactly 180° out of phase, and cancel each other, whereas when the time delay corresponds to one whole wavelength, the waves combine constructively. If the amplitudes of the two waves are the same, then total nulling and doubling, respectively, of the resultant wave occurs.
  • the magnitude of the effect can be controlled.
  • the time delay is chosen to be 1 ms
  • the first cancellation point exists at 500 Hz.
  • the first constructive addition frequency points are at 0 Hz, and 1 kHz, where the signals are in phase. If the attenuation factor is set to 0.5, then the destructive and constructive interference effects are restricted to -3 dB and +3 dB respectively. These characteristics are shown in Figure 1 (lower).
  • Inversion can be achieved either by (a) changing the summing node to a "differencing" node (for signal subtraction), or (b) inverting the attenuation coefficient (e.g. from +0.5 to -0.5); the end result is the same in both cases.
  • the output of such a pair of complementary filters exhibits maximal amplitude decorrelation within the constraints of the attenuation factors, because the peaks of one correspond to the troughs of the other ( Figure 2), and vice versa.
  • a source "triplet" were required, then a convenient method for creating such an arrangement is the creation of a pair of maximally decorrelated sources, which are then used in conjunction with the original source itself, thus providing three sources.
  • Audible artefacts As can be seen in Figure 1, the property of a comb filter is to create a series of notches and peaks throughout the spectrum, with the frequency of the lowest feature determined by the time-delay of the filter. Our hearing processes are particularly good at noticing notches in the audio spectrum, and we are also good at detecting tones and notches which are repeated at octave intervals (where the frequencies are multiple values of a fundamental value). Consequently, a comb-filtered signal sounds very artificial, tonally.
  • Doppler interaction When more than one comb-filtered signals are subjected to Doppler-effect type processing (as happens in computer game audio applications), then the comb artefacts in the audio become exaggerated, apparently by the interaction between the comb features. Even if one uses complementary comb-filters to make the sources, as described above, the Doppler processing can shift the features in the frequency domain such that they "slide” over each other and become noticeable as artefacts. Notches which are caused to "move” in the frequency domain are especially noticeable: a good example of this is the "flangeing" effect used for music-effects processors, and another is the effect which is heard as a steam train arrives, hissing, at the station platform.
  • the hiss sound is, approximately, a form of white noise, and it arrives at the listener both directly and also reflected from the platform surface where it combines with the direct path sound.
  • the time-delay difference between the two is small when the train is distant, but increases to correspond to a path length of about twice the listener's ear height above ground when the sound source is above the listener's head and close. For example, if the train were about 4 m distant (with an elevated source), and the ear height were 1.8 m, then the delay would be about 4 ms, and so the first (lowest) notch would occur at about 125 Hz.
  • the present invention is a means of decorrelating a sound source so as to provide one or more sound sources which can be used for 3D-sound synthesis such that they can be perceived independently of one another.
  • the invention is advantageous over the use of simple comb-filtering, in that: (a) there are no significant audible artefacts present; (b) the derived sources can be Doppler processed without flangeing artefacts, and (c) a plurality of sources can be derived from one single source.
  • It includes an audio delay-line (1), which is tapped at two (or more) points within a prescribed range, said points changing frequently and randomly.
  • the outputs of the tap nodes are multiplied by predetermined gain factors, one of which is negative, and then added to the original signal. The effect of this is to cause the spectral profile of the derived signal to change, continually, with respect to the original (and, similarly, there are continual changes in relative phase).
  • the central feature is an audio delay line (1) in the form of a buffer, as shown at the top of Figure 3, to which audio is written via the "audio write” pointer (2).
  • the current data byte is read via the "t 0 " pointer (3).
  • the "audio write” pointer (and all the data pointers) moves incrementally towards the right after each sample has been written.
  • the audio sampling rate will be 44.1 kHz, and hence the corresponding sampling period is about 22.68 ⁇ s.
  • the processing blocks Q and R both comprise a crossfader and a fixed gain amplifier (or attenuator), and the Q block also contains an inverter.
  • Each crossfader has two audio inputs and a single audio output. One input to each crossfader is connected so as to receive audio data from a read pointer in the "A" range, and the other input is connected so as to receive audio data from a read pointer in the "B" range.
  • the crossfader is set to transfer signal to the output from one of the inputs with a gain of unity, and from the other input with a gain of zero.
  • a crossfade cycle rate of greater than 0.5 Hz, preferably 5 - 100 cycles per second is chosen, although much higher cycle rates can, in principle, be used.
  • the Q and R processing block gain stages have fixed gain (or attenuation). It is convenient, but not essential, that they are set equal to one another, because the decorrelation contributions from both cells would be equally weighted. It is also convenient that the sum of all the gain stages (G P , G Q and G R ) is unity, because this corresponds to a maximum overall gain of unity (0 dB) through the system with respect to the original audio signal written to the buffer.
  • the output from the Q and R sections are fed into a summing node, together with the output from the t 0 "read" pointer, which is transferred to the node via a fixed gain stage, Gp (4).
  • the output of the summing node is the final system output: the dynamically decorrelated signal.
  • the system is initialised prior to use: (a) the "write" and "t 0 " pointers are allocated; (b) the R 1 , R 2 , Q 1 and Q 2 pointers are allocated to random locations within their respective ranges (the R 1 and Q 2 pointers always lie in the "B" range of the buffer, and the R 2 and Q 1 pointers always lie in the "A” range of the buffer); (c) the gain of the Q and R gain stages is set; and (d) the Q and R crossfaders are configured such that, initially, the Q 1 and R 1 pointers transfer data to the Q and R gain blocks with unity-gain, and from the Q 2 and R 2 pointers with zero-gain.
  • the first audio sample is written into the buffer. Data is read from all "read” taps, processed by the associated crossfaders and gain stages, and then summed by the summing (output) node.
  • the pointers are all shifted by one sample (to the right in Figure 3), ready for the next read/write event, and the crossfaders are incremented.
  • the gain of the zero-gain crossfade path i.e. Q 2 and R 2 at this point
  • the gain of the zero-gain crossfade path is increased by a factor of: ⁇ crossfade cycle period ⁇ x ⁇ sample frequency ⁇ .
  • the gain factor for the zero-gain crossfade path would be increased from 0 to 1/8192.
  • the gain factor for the unit gain (at this point) crossfade path would be decreased from 1 to 8191/8192. Items 2 and 3 are repeated until the crossfade from Q 1 to Q 2 (and R 1 to R 2 ) has fully occurred, after 8192 samples (see Figure 4). At this point, the gain contribution from pointers Q 1 and R 1 is zero, and they are reallocated to new, random positions within their specified ranges.
  • the crossfade process is now reversed so as to fade progressively, sample by sample, to these newly allocated taps, such that after another 8192 samples (16384 in all), the unity-gain path is, once again, from pointers Q 1 and R 1 , and the zero-gain path from Q 2 and R 2 , at which point they are reallocated to new, random positions within their specified ranges. This cyclic process is repeated continually.
  • the output signal at this point in time is the sum of three vectors (in contrast to the comb filter described earlier, which is the sum of only two vectors), although it is the sum of five vectors almost all of the time.
  • An amplitude spectrum of the resultant signal created by the parameters used in the above example is shown in Figure 5.
  • the maximum gain is unity (0 dB), which occurs when all three contributions are effectively in phase (taking account of the inverter) and because the gains are 0.50, 0.25 and 0.25.
  • the spectral profile is somewhat pseudo-randomly aperiodic (albeit not perfectly so), unlike that of a comb filter, which is perfectly regular and periodic. This feature is important because the profiling is much less audible as an artefact, making the overall effect "tone-neutral".
  • the output signal is the sum of the three vectors, but now the pseudo-random modifications of the amplitude and phase spectra are different because of the changed tap locations, as is indicated by the amplitude spectrum shown in Figure 6, which also includes the previous data of Figure 5 to show the differences. (The phase spectra have not been shown here because they are relatively meaningless owing to the "wrap-around" effect which happens when phase differences exceed 2 ⁇ .)
  • the decorrelated spectral profile of Figure 5 has been gradually transformed into the spectral profile of Figure 6 (solid line) in about one fifth of a second, and it continues to change, smoothly, continuously and randomly, within the constraints of the specified parameters.
  • the main applications are related to (a) Sensaura ZoomFX; (b) the virtualisation of Dolby Digital (creating several right-surround and left-surround sources, rather than a single pair, thus creating a "diffuse" sound-field effect as is important for THX -specified systems), and (c) the virtualisation of Dolby Surround for headphones, creating a pair of decorrelated rear channels from the single, provided surround channel.

Claims (8)

  1. Verfahren zur Erzeugung eines zweiten Audiosignals (DDC out) aus einem ersten Audiosignal (1) zur Verwendung beim Synthetisieren eines dreidimensionalen Klangfeldes, wobei das zweite Audiosignal derart aus dem ersten Audiosignal dekorreliert wird, dass es im Betrieb von einem Zuhörer als von dem ersten Audiosignal unabhängig wahrgenommen werden kann, wobei das Verfahren die folgenden Schritte umfasst oder aus ihnen besteht: a) Ableiten eines ersten verzögerten Audiosignals (Q) aus dem ersten Signal; b) Multiplizieren dieses ersten verzögerten Audiosignals mit einem Verstärkungsfaktor zwischen null und minus eins zum Erhalt eines ersten verzögerten, Pegel-angepassten Audiosignals; c) Ableiten eines zweiten verzögerten Audiosignals (R) mit einer von dem ersten verzögerten Audiosignal abweichenden Verzögerungszeit aus dem ersten Signal; d) Multiplizieren dieses zweiten verzögerten Audiosignals mit einem Verstärkungsfaktor zwischen null und plus eins zum Erhalt eines zweiten verzögerten, Pegel-angepassten Audiosignals; und e) Kombinieren dieser ersten und zweiten verzögerten, Pegel-angepassten Signale mit dem ersten Audiosignal oder einer zeitlich verzögerten (to) Version des ersten Audiosignals, um das zweite Audiosignal zu erzeugen, dadurch gekennzeichnet, dass die ersten und zweiten verzögerten Audiosignale um Zeitperioden verzögert werden, die dazu veranlasst werden, sich in einer zufälligen oder pseudo-zufälligen oder quasi zufälligen Weise zu verändern.
  2. Verfahren nach Anspruch 1, bei dem sich die Verstärkungsfaktoren der ersten und zweiten verzögerten, Pegel-angepassten Signale auf null summieren.
  3. Verfahren nach Anspruch 1 oder 2, bei dem die Verzögerungszeiten dazu veranlasst werden, sich mit einer Frequenz von größer als 0,5 Hz zu verändern.
  4. Vorrichtung zum Erzeugen eines zweiten Audiosignals (DDC out) aus einem ersten Audiosignal zur Verwendung beim Synthetisieren eines dreidimensionalen Klangfeldes, wobei das zweite Audiosignal derart aus dem ersten Audiosignal dekorreliert wird, dass es im Betrieb von einem Zuhörer als von dem ersten Audiosignal unabhängig wahrgenommen werden kann, wobei die Vorrichtung eine Audiosignal-Laufzeitschaltung (1) umfasst oder aus ihr besteht, mit dem ersten Audiosignal als Eingangssignal und einer Mehrzahl von Ausgangs-Abgriffpunkten (2) mit jeweils einer entsprechend unterschiedlichen Verzögerungszeit innerhalb eines vorbestimmten Bereichs von Verzögerungszeiten, wobei die Ausgangssignale von jedem Abgriffpunkt dieser Mehrzahl mit einem ausgewählten Verstärkungsfaktor (4) vervielfältigt werden, wobei einer der ausgewählten Verstärkungsfaktoren negativ und einer der ausgewählten Verstärkungsfaktoren positiv ist, wobei die Mehrzahl der Pegel-angepassten Ausgangssignale von den Ausgangs-Abgriffpunkten mit dem ersten Audiosignal oder einer zeitlich verzögerten Version des ersten Audiosignals kombiniert werden, um das zweite Audiosignal zu erzeugen, dadurch gekennzeichnet, dass den jeweiligen unterschiedlichen Verzögerungszeiten, die jedem Ausgangs-Abgriffpunkt entsprechen, ausgewählte feste Werte zugeordnet sind, welche so angeordnet sind, dass sie sich in andere feste Werte innerhalb des vorbestimmten Bereichs von Verzögerungszeiten umwandeln.
  5. Vorrichtung nach Anspruch 4, wobei die Mehrzahl ausgewählter Verstärkungsfaktoren sich auf null summiert.
  6. Vorrichtung nach Anspruch 4 oder 5, wobei die ausgewählten festen Werte so angeordnet sind, dass sie sich bei einer Frequenz größer als 0,5 Hz in andere feste Werte umwandeln.
  7. Vorrichtung nach Anspruch 4 bis 6, wobei die ausgewählten festen Werte der jeweiligen abweichenden Verzögerungszeiten in einer zufälligen oder pseudo-zufälligen oder quasi zufälligen Weise umgewandelt werden.
  8. Vorrichtung nach Anspruch 4 bis 7, wobei das zweite Audiosignal aus dem ersten Audiosignal oder einer zeitlich verzögerten Version des ersten Audiosignals und zwei Ausgangs-Abgriffpunkten oder zwei Gruppen von überblendeten Ausgangs-Abgriffpunkten erzeugt wird, wobei die Amplitude des Ausgangssignals von einem beliebigen Abgriffpunkt null ist, wenn die Verzögerungszeit des betreffenden Anzapfungspunktes von einem festen Wert zu einem anderen verändert wird.
EP00956732A 1999-09-04 2000-09-04 Verfahren und anordnung zur erzeugung eines zweiten audiosignales von einem ersten audiosignal Expired - Lifetime EP1212923B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB9920811A GB2353926B (en) 1999-09-04 1999-09-04 Method and apparatus for generating a second audio signal from a first audio signal
GB9920811 1999-09-04
PCT/GB2000/003393 WO2001019138A2 (en) 1999-09-04 2000-09-04 Method and apparatus for generating a second audio signal from a first audio signal

Publications (2)

Publication Number Publication Date
EP1212923A2 EP1212923A2 (de) 2002-06-12
EP1212923B1 true EP1212923B1 (de) 2004-04-21

Family

ID=10860265

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00956732A Expired - Lifetime EP1212923B1 (de) 1999-09-04 2000-09-04 Verfahren und anordnung zur erzeugung eines zweiten audiosignales von einem ersten audiosignal

Country Status (5)

Country Link
EP (1) EP1212923B1 (de)
AT (1) ATE265128T1 (de)
DE (1) DE60010100D1 (de)
GB (1) GB2353926B (de)
WO (1) WO2001019138A2 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATE426235T1 (de) 2002-04-22 2009-04-15 Koninkl Philips Electronics Nv Dekodiervorrichtung mit dekorreliereinheit
SE0301273D0 (sv) * 2003-04-30 2003-04-30 Coding Technologies Sweden Ab Advanced processing based on a complex-exponential-modulated filterbank and adaptive time signalling methods
FR2853804A1 (fr) * 2003-07-11 2004-10-15 France Telecom Procede de decodage d'un signal permettant de reconstituer une scene sonore et dispositif de decodage correspondant
TWI393121B (zh) 2004-08-25 2013-04-11 Dolby Lab Licensing Corp 處理一組n個聲音信號之方法與裝置及與其相關聯之電腦程式
US8238560B2 (en) 2006-09-14 2012-08-07 Lg Electronics Inc. Dialogue enhancements techniques

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8303945A (nl) * 1983-11-17 1985-06-17 Philips Nv Inrichting voor het realiseren van een pseudo-stereo signaal.
GB9107011D0 (en) * 1991-04-04 1991-05-22 Gerzon Michael A Illusory sound distance control method
WO1994022278A1 (en) * 1993-03-18 1994-09-29 Central Research Laboratories Limited Plural-channel sound processing
JP2959361B2 (ja) * 1993-10-21 1999-10-06 ヤマハ株式会社 残響音付加装置
US5774560A (en) * 1996-05-30 1998-06-30 Industrial Technology Research Institute Digital acoustic reverberation filter network
GB9627015D0 (en) * 1996-12-28 1997-02-19 Central Research Lab Ltd Processing audio signals

Also Published As

Publication number Publication date
WO2001019138A3 (en) 2001-11-15
ATE265128T1 (de) 2004-05-15
EP1212923A2 (de) 2002-06-12
WO2001019138A2 (en) 2001-03-15
DE60010100D1 (de) 2004-05-27
GB9920811D0 (en) 1999-11-10
GB2353926A (en) 2001-03-07
GB2353926B (en) 2003-10-29

Similar Documents

Publication Publication Date Title
EP3311593B1 (de) Binaurale audiowiedergabe
ES2249823T3 (es) Descodificacion de audio multifuncional.
US5173944A (en) Head related transfer function pseudo-stereophony
US5546465A (en) Audio playback apparatus and method
US20070223751A1 (en) Utilization of filtering effects in stereo headphone devices to enhance spatialization of source around a listener
US6658117B2 (en) Sound field effect control apparatus and method
EP3895451B1 (de) Verfahren und vorrichtung zur verarbeitung eines stereosignals
JP2005354695A (ja) オーディオ信号処理
EP2530956A1 (de) Verfahren zur Erzeugung eines Surround-Audiosignals aus einem Mono-/Stereo-Audiosignal
US5844993A (en) Surround signal processing apparatus
WO2002015637A1 (en) Method and system for recording and reproduction of binaural sound
JP2956545B2 (ja) 音場制御装置
US6754352B2 (en) Sound field production apparatus
EP1212923B1 (de) Verfahren und anordnung zur erzeugung eines zweiten audiosignales von einem ersten audiosignal
EP0959644A2 (de) Verfahren zur Veränderung eines Filters zum Implementieren einer Kopfbezogene-Übertragungsfunktion
US7796766B2 (en) Audio center channel phantomizer
GB2369976A (en) A method of synthesising an averaged diffuse-field head-related transfer function
GB2366975A (en) A method of audio signal processing for a loudspeaker located close to an ear
Sibbald Transaural acoustic crosstalk cancellation
WO2024081957A1 (en) Binaural externalization processing
AU751831C (en) Method and system for recording and reproduction of binaural sound
Shim et al. Sound field processing system using grouped reflections algorithm for home theater systems
Basha et al. Stereo widening system using binaural cues for headphones
Bejoy Virtual surround sound implementation using deccorrelation filters and HRTF
Eargle Two-Channel Stereo

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20020321

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

17Q First examination report despatched

Effective date: 20030127

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 20040421

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040421

Ref country code: FR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040421

Ref country code: CH

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040421

Ref country code: LI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040421

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040421

Ref country code: AT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040421

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040421

Ref country code: BE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040421

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

REF Corresponds to:

Ref document number: 60010100

Country of ref document: DE

Date of ref document: 20040527

Kind code of ref document: P

RAP2 Party data changed (patent owner data changed or rights of a patent transferred)

Owner name: CREATIVE TECHNOLOGY LTD.

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040721

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040721

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040721

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040722

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20040801

NLT2 Nl: modifications (of names), taken from the european patent patent bulletin

Owner name: CREATIVE TECHNOLOGY LTD.

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040904

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040904

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040906

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MC

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040930

NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

EN Fr: translation not filed
26N No opposition filed

Effective date: 20050124

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20040904

REG Reference to a national code

Ref country code: IE

Ref legal event code: MM4A

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: PT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040921