EP1410678A2 - Procede et systeme de transmission et/ou de reception de signaux audio dans le sens souhaite - Google Patents

Procede et systeme de transmission et/ou de reception de signaux audio dans le sens souhaite

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Publication number
EP1410678A2
EP1410678A2 EP02707081A EP02707081A EP1410678A2 EP 1410678 A2 EP1410678 A2 EP 1410678A2 EP 02707081 A EP02707081 A EP 02707081A EP 02707081 A EP02707081 A EP 02707081A EP 1410678 A2 EP1410678 A2 EP 1410678A2
Authority
EP
European Patent Office
Prior art keywords
signals
acoustic
acoustic signals
deshed
signal
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.)
Withdrawn
Application number
EP02707081A
Other languages
German (de)
English (en)
Inventor
David Zlotnick
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.)
D-START ADVANCED TECHNOLOGIES Ltd
Original Assignee
D-Start Advanced Technologies Ltd
START ADVANCED TECHNOLOGIES LT
Zlotnick David
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 D-Start Advanced Technologies Ltd, START ADVANCED TECHNOLOGIES LT, Zlotnick David filed Critical D-Start Advanced Technologies Ltd
Publication of EP1410678A2 publication Critical patent/EP1410678A2/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/005—Circuits for transducers, loudspeakers or microphones for combining the signals of two or more microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/02—Constructional features of telephone sets
    • H04M1/19—Arrangements of transmitters, receivers, or complete sets to prevent eavesdropping, to attenuate local noise or to prevent undesired transmission; Mouthpieces or receivers specially adapted therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/12—Circuits for transducers, loudspeakers or microphones for distributing signals to two or more loudspeakers

Definitions

  • This invention is generally in the field of ttansnnssion/receiving of acoustic signals and relates to a method and system for ttansnutting and/or receiving acoustic signals in and/or from a desired direction.
  • the invention is particularly useful with a communication device, such as a phone device, for increasing the directionality of ttansnutting and receiving acoustic signals to and from a subject location, voice operated system such a computer program, as well as television and other audio sets.
  • a voice communication device such as a phone device (e.g., mobile phone), personal computer or Palm device, typically utilize one of three main alternative techniques:
  • the first technique either requires a spare hand, or limits the speaker's free movement. Furthermore, a mobile phone is a source of emits? radiation that is suspected to be hazardous.
  • the second technique is also inconvenient because a wired earphone and microphone unit has the same limitation of movement, while a wireless unit is clumsy and may be unsafe due to its RF transmission output.
  • the third technique suffers from such disadvantages as high sensitivity to background noise, no privacy for the speakers, and a low quality of sound for both parties.
  • US Patent No. 5,901,232 discloses a technique for detecting the position (coordinates) of an external sound source and pointing (rotating) a paraboloid microphone/speaker towards the detected position.
  • US Patent No. 5,657,393 discloses a device having several microphones and utilizing enhancement of an external sound signal received by the microphones.
  • the device utilizes a suitable time delay to each microphone channel to compensate for the difference in distance, and a propagation delay from the sound source to each microphone channel. This is implemented by reading the samples of the different microphone channels from a memory at different subsequent periods in accordance with the desired delay.
  • An amphtude distributor circuit is used to modify the digitized amplitudes of the outputs of the sub-array to reduce the beam side-lobe levels.
  • US Patent No. 5,121,426 discloses a loudspeaker telephone station (speakerphone) that includes a loudspeaker and one or more directional microphones within the same housing station to overcome the creation of sustained oscillation ("singing"), emerging from the proximity between the loudspeaker and the microphones in the system.
  • the microphones have a polar response characteristic that includes a major lobe, one or more side-lobes, and nulls in-between.
  • the loudspeaker is positioned in the null of the polar response characteristic that resides between the major lobe and an adjacent side lobe.
  • the microphone apparatus is positioned so that its major lobe is aimed in a direction that is generally perpendicular to the direction that the loudspeaker is aimed at, such as to substantially reduce the acoustic coupling between the loudspeaker and the microphones.
  • Means are provided for increasing the distance between input sound ports of a frrst-order-gradient (FOG) microphone and thereby improving its sensitivity.
  • a pair of such improved FOG microphones is used in assembling a second-order-gradient microphone. Full duplex operation is achieved when a pair of echo cancellers is added to further reduce the coupling between the transmit- and receive-directions of the speakerphone.
  • US Patent No. 6,041,127 discloses a technique of producing a response pattern of a microphone array having an adjustable orientation of maximum reception. This is implemented by detecting difference signals between the pairs of the individual microphone output signals, and actuating a selected pair of microphones to receive signals.
  • a directional microphone system is described in US Patent No. 5,483,599.
  • the system comprises at least two microphones utilizing a surnming means for producing a sum signal of the signals produced by the microphones, a product means for producing a product of the at least two signals d a mixing means for combining the signals for the presentation to the summing and product means.
  • the mixing and summing means includes a signal time delay means so that at least some of the signals are time delayed before they are summed.
  • Signals coming from directions other than directly perpendicular to the two microphones are attenuated first by the surriming means, since they may not be in phase, and secondly by a gain circuit, which is controlled by a multipher, since the product of signals not in phase falls off rapidly with the increase in the angle away from perpendicular.
  • a low-pass filter in conjunction with a rectifier causes the multipher to function as a cross-correlation mechamsm which effectively rejects all mcoming signals that are not precisely in phase.
  • the main idea of the present invention consists of utilizing an array (generally, at least two) of omni-directional transmitters and/or receivers of acoustic signals, and processing signals to be transmitted as acoustic signals and/or processing received acoustic signals with a wavelet packet transform model.
  • the model (algorithm) performs spatial filtering of signals received by the acoustic receivers and/or a signal to be transmitted by acoustic transmitters, as the case may be.
  • This filtering consists of suppressing energy components coming from directions other than the desired direction (defined by the subject location relative to the receivers), and/or directional beam forming of a beam to be transmitted by the acoustic ttansntitting devices such as to be directed substantially in the desired direction (towards the subject).
  • the received signal are thus composed in a way that performs spatial filtering from the desired direction.
  • the desired direction of the transmission/reception can be determined utilizing a suitable technique for identifying the relative location of the subject.
  • the Wavelet Packet Transform based approach is a frequency and time domain transform, and has been disclosed for example in the following publications:
  • signal processing with the wavelet packet transform model includes decomposing the signal into a matrix of sub-signals, wherein each sub-signal is a base function of frequency and time multiplied by a predeterrr ⁇ ned coefficient characterizing energy of the respective sub-signal, hi order to create a preferred (desired) direction for signal transmission, or collect coming acoustic signals substantially from a desired direction, the coefficients are optimized in accordance with the desired direction such that the maximal energy in the processed signal is that associated with the desired direction.
  • a method for conttolling one or both of tt-ms ⁇ titting acoustic signals from at least two tiansntitting devices in a desired direction towards a subject location and receiving acoustic signals propagating in a desired direction from a subject location by at least two receiving devices comprising:
  • the collected signals are digital signals to be transmitted to the subject as acoustic signals through the at least two frans ⁇ tting devices.
  • the ttansntitting devices are operable by the digital output signal to generate and transmit an acoustic signal shaped such that the maximal energy of the transmitted acoustic signal is directed substantially in the desired direction.
  • the collected signals are digital signals representative of acoustic signals received by the receiving devices. These digital signals are thus processed to produce the output digital signal whose maximal energy is that collected substantially from the desired direction (from the subject location).
  • the processing of the collected signals consists of effective filtering out of the collected signals background noise and/or acoustic signals from directions other than the desired direction.
  • the case may be such that an acoustic receiver-subject and/or acoustic transmitter-subject is positioned stationary at a known location with respect to the ttansmittkg/receiving devices, and the regular non-directional ttansnntt g/receiving devices are to periodically transmit/receive acoustic signals to or from the subject, hi this case, data indicative of the desired direction is previously determined and stored in the memory utility of the processor.
  • the data indicative of the desired direction is to be obtained each time the ttansrnitting/receiving process is to be started.
  • this data also has to be dynamically determined during the process.
  • the data indicative of the desired direction (defined by the location of the subject relative to the ttansrmttmg/receiving devices) can be obtained by receiving external acoustic signals including those coming from the subject location, and analyzing the received acoustic signal. Analyzing the received acoustic signals can be a med at identifying whether the received acoustic signals include signals associated with an authorized subject.
  • the audio signature of the authorized person is previously determined and stored. Identification of the signature can utilize a wavelet packet transform approach.
  • the optimal wavelet packet transform model is previously selected and stored.
  • the analyzing of the received acoustic signals can be aimed at deter ⁇ iing the audio signature of a specific person.
  • a person who intends to use a system of the invention actuates the system by starting to speak to enable the location of the direction from which the person is speaking, and detemiine his her audio signature.
  • more than one wavelet packet transform model can be preset in order to select the optimal one in response to the determined audio signature.
  • Obtaining the data indicative of the desired direction can be based on the generation of an excitation (control) signal to be transmitted from the vicinity of the tiansn ⁇ tting/receiving devices to thereby produce a response to the control signal generated at the subject location by an external device (e.g., attachable to a person).
  • an excitation (control) signal may be an acoustic signal (e.g., ultrasound).
  • a person tending to use a system of the present invention e.g., phone system
  • a suitable acoustic transceiver designed to match the signal generator of the system, or an acoustic reflector.
  • At least one of said at least two tiansntitting devices can be used to transmit the control signal, and the array (at least two) of the receiving devices can be used to receive the response.
  • the processing of the collected signals with the selected wavelet packet transform model includes providing digital representation of the collected signals and decomposing each of the collected digital signals into a matrix of sub-signals, each being a base function of both frequency and time, multiplied by a predetermined coefficient characterizing the energy component of the respective sub-signal. These coefficients are optimized in accordance with the desired direction to shape the output signal such that the maximal energy is that associated with the desired direction.
  • the subject e.g., person
  • the system is preferably preprogrammed for dynamically deterrnining the relative position of the subject and dynamically optimizing the coefficients in accordance with the variations of the maximal energy direction.
  • a system for conttolling one or both ttansntitting acoustic signals in a desired direction towards a subject location and receiving acoustic signals propagating in a desired direction from a subject location comprising:
  • the system also comprises a direction finding utility operable to identify the subject location relative to the system, and thereby obtain data indicative of the desired direction for ttansrmtting and/or receiving acoustic signals by the system substantially in and/or from this direction.
  • Such a system utilizing only the directional transmission of acoustic signals may be used with an audio set, e.g., TV or radio set.
  • a system utilizing only the directional reception of acoustic signals may be used with a computer device, such as a personal computer (e.g., laptop) or PDA, aimed at carrying out speech recognition or voice operation of a specific software application, for example, word processing software, or computer games.
  • a system utilizing both the directional signal transmission and direction signal reception may be used with a phone system (e.g., mobile phone, speakerphone, car phone), or a computer system for caixying out Intercom session, video conference, etc.
  • the term "used with” signifies that the system is either a separate unit connectable to the respective device (e.g., a phone device) through signal transmission (wire-based or wireless), or is a part of the respective device.
  • a system for ttansntitting acoustic signals substantially in a desired direction and receiving acoustic signals substantially from the desired direction comprising:
  • a processor connectable to the communication utility, the acoustic receiving array, and the acoustic tiansnutting array, the processor being responsive to digital signals representative of acoustic signals received by the receiving array to process them with a selected wavelet packet transform model in accordance with data indicative of the desired direction and produce an output digital signal to operate the communication utility, said output signal to the communication utility being shaped such that maximal energy of said output signal is that received by the receivers substantially from the desired direction, the processor being responsive to digital signals representative of signals collected by the communication utility to process them with a selected wavelet packet transform model in accordance with the data indicative of the desired direction and produce an output digital signal to operate the acoustic ttansn ⁇ tting array, said output signal to the acoustic ttansn ⁇ tting array being shaped such that maximal energy of said output signal is directed substantially in the desired direction.
  • the present invention can be used with a mobile phone device.
  • Mobile communication devices today are small hand-held devices with an RF transceiver incorporated in them.
  • RF transceiver incorporated in them.
  • the technique of the present invention limits the problem associated with RF radiation by the communication device by providing directional transmission and reception of audio signals. This enables conducting a communication session with there being neither the need to hold the phone device close to the person's head, nor to equip the phone device with additional means for reducing RF radiation.
  • FIG. 1 A illustrates schematically the system according to one example of the present invention
  • Fig. IB is a flowchart of the process according to the present invention.
  • FIG. 2 illustrates schematically the system according to another example of the present invention
  • Figs. 3A and 3B illustrate the system according to yet another example of the present invention
  • Fig. 4 illustrates a flow diagram of an initial stage in the operation of the system of Figs. 3A-3B aimed at deternriering the desired direction of signal transmission/reception;
  • Fig. 5 shows the principles of a wavelet packet decomposition process.
  • a system 100 according to one embodiment of the invention, h the present example, the system 100 is used with a personal computer 102 for voice operation of a specific programming utility 104 (e.g., word processing software).
  • the system is to be operated by voice (audio) signals coming from a specific person at a subject location TL.
  • the system 100 comprises such main constructional parts as a microphone assembly, generally at 106, and a processor 108 (which may be implemented on the CPU of the personal computer) connected to the output of the microphones and preprogrammed to process digital data representative of the received audio signals to thereby control the signal reception process.
  • a direction finding utility 110 which may be part of the processor 108 or may include a separate device as in the present example of Fig 1A.
  • the microphone assembly 106 is composed of an array of microphones (generally, at least two microphones, constituting receiving devices for receiving audio signals) - four such microphones 106A, 106B, 106C and 106D being shown in the present example of Fig. 1A.
  • the microphones are regular omm-directional microphones for receiving audio signals (AS(A), AS B), AS( , AS( ⁇ )) from within the surroundings of the system.
  • the microphones may be arranged in a one- or two-dimensional array (which may be linear or circular), where the distance between two locally adjacent microphones may and may not be the same.
  • the output of the microphones 106 is connected to the processor 108 through an A D converter 112 to thereby provide digital input data components H)(A) - DD ) to the processor 108 that are representative of the audio signals AS(A>- AS(D> collected by the microphones, respectively
  • the direction finding utility 110 is designed and operable to locate the direction from the subject relative to the system 100 and thereby enable determination of the desired direction for the signal reception, hi the present example, the direction finding utility 110 is composed of two remote units 110A and HOB capable of cormnunicating with each other through signal transmission, wherein the unit 110A is incorporated in the system 100, and the unit HOB is positioned at the subject location (e.g., is attached to a person intended for operating the word processing software).
  • the unit 110A may be an ultrasound transceiver
  • the unit HOB may be either a shnilar transceiver matching the transceiver 110A or may be a reflector of ultrasound waves.
  • the direction finding utility 110 can be implemented by one of the following means:
  • Passive unit - a mimature retio-directive device HOB (a passive acoustic echo reflector) to be accommodated at the subject location, e.g., attachable to the user, to reflect a control signal (e.g., ultrasound signal, or a very short audio pulse unheard by the human ear) transmitted by the system 100 (through an appropriate ttansn ⁇ tting device - unit 110A), wherein the control signal may be encoded to thereby enable the use of a specific control signal for communicating with a specific person.
  • HOB a passive acoustic echo reflector
  • Active unit - a miniature acoustic transmitter HOB attachable to the user for ttansntitting a special acoustic signal (audio or ultrasound) unheard by the human ear that is to be received by the microphone assembly of the system 100.
  • the special acoustic signal may be encoded to identify the user.
  • Active unit - a miniature infrared emitter HOB attachable to the user for ttansntitting an infrared signal (e.g., encoded signal) that is to be received by an infrared detector 110A.
  • Software application incorporated within the processor 108 (or another processing utility) and capable of identifying the voice pattern of a speaker.
  • the same microphone assembly 106 may be used for collecting external acoustic signals including those coming from the subject, to be processed by the processor 108.
  • the speaker may actuate the direction finding utility through the system interface, e.g., press a button and start speaking (e.g., pronouncing a keyword or key phrase) thereby enabling the software to learn and store the voice pattern of the specific speaker, or identify the voice pattern of the specific speaker provided the person's audio signature has been previously determined and stored.
  • a biometiic detecting device either one-part device incorporated in the system 100, or a two-part device having one part 110A at the system and the other part HOB attachable to a person.
  • a biometiic detecting device is of the kind capable of identifying the presence of a person in the vicinity of the system 100 by sensing one or more of the person's biometiic attributes, such as heartbeat, breath sound or body temperature (infrared radiation).
  • the direction finding utility includes a data processing and analyzing utility, which may be part of the processor 108.
  • the data analysis technique may be similar to that disclosed in US Patent No. 5,600,727. According to this technique, acoustic pulses generated by several loudspeakers are received by each of several microphones, the time-of-flight for each pulse to each microphone is measured, and the distance and angular displacement of each microphone from a predetermined reference are derived.
  • the data indicative of the desired direction may be obtained by applying Fourier Transform analysis, or any other method based on time delay in signal reception by multiple microphones, to signals received from the identified subject location (e.g., an acoustic signal sent from a transmitter at the subject location or reflected in response to the control signal by an acoustic reflector).
  • the data analysis may include the wavelet packet transform approach, as will be described further below.
  • the provision of the direction findmg utility 110 enables to locate the required sound source (subject) among the multiple of sources. It should also be noted that location of the subject can be dynamically carried out, e.g., by preprogramming the system to continuously or periodically actuating the operation of the direction finding utility 110, to thereby track the position of the specific person with respect to the system 100.
  • the processor 108 is preprogrammed to utilize data indicative of a desired direction for signal reception (defined by relative location of the subject) to process digital data representative of the audio signals received by the microphones, and provide an output signal OD characterized by that its maximal energy is substantially that coming in a direction from the subject location TL to the system 100.
  • the processing of the input digital data is based on shaping it in accordance with a selected wavelet packet transform model, as will be described more specifically further below.
  • the so-produced output signal is received by the word processing software 104, thereby increasing signal-to-noise ratio of the signal intended for operating this software, considering noise audio signals coming from directions other than the desired one.
  • step I the direction finding utility 110 is actuated, either by the processor 108 to transmit a control signal, or by a person (e.g., by pressing a button on the system 100 and starting speaking), to thereby locate the specific (authorized) person and generate data indicative of his/her location (i.e., of the subject location).
  • the processor 108 receives this data and analyzes it to determine an angle (or angles) defining the maximal energy direction to be created (step A).
  • the data analysis may include the wavelet packet transform approach, as will be described further below.
  • microphones continue receiving audio signals (step HI) and generating data indicative thereof.
  • Digital data representative of the audio signals received by the microphones enter the processor 108, which applies a selected wavelet packet transform model to these digital data (step IV) and generates an output signal OD shaped as described above.
  • Fig. 2 illustrates a system 200 according to another example of the invention.
  • the system 200 is used with a television (or audio) set 202 for ttansntitting audio output signals AO(A>, AO B and AO(Q generated by the TV set 202 towards a specific location (subject location) TL.
  • the system 200 comprises a loudspeakers' assembly 206, e.g., composed of three loudspeakers 206A-206C; and a processor 108.
  • the system 200 also comprises a direction finding utility 110 (one or two-part utility as described above).
  • the processor 108 controls the signal transmission process, and is connected to an antenna 204 (constituting a communication utihty) of the TV set to receive input collected signals ID that are to be transmitted as audio signals through the loudspeakers, and to the loudspeakers to supply thereto digital data components (signals) OD (A )-OD( Q .
  • the latter are results of processing the collected signal ED with the wavelet packet transform model in accordance with data indicative of a desired direction, and are such that the shape of the entire output signal from the loudspeakers corresponds to the maximal energy propagation in the desired direction, i.e., to the subject location.
  • each loudspeaker is associated with a D/A converter, generally at 212, connected to the processor 108.
  • the system 300 is used with a phone device 302, e.g., a mobile phone device. Similarly, the same reference numbers are used for identifying those components, which are identical in the system 100 or 200 and in the system 300.
  • the system 300 comprises a microphones' assembly 106, e.g. composed of four standard telecommunication (semi-directional) microphones 106A-106D, and a loudspeakers' assembly 206, e.g., composed of four standard telecommunication narrow-directional loudspeakers 206A-206D; and a processor 108.
  • a direction finding utility 110 utilizes a retto-directive unit HOB attached to a person.
  • the processor 108 controls both the transmission and reception processes.
  • the processor 108 is connected to a communication utility 304 of the phone device 302 (e.g., cellular RF unit in a mobile phone or a cable in a telephone) to receive both input signals H> received from a communication network to be transmitted as audio signals through the loudspeakers, and an output signal OD generated by the processor as a result of processing audio signals AS (A) -AS (D ) collected by the microphones.
  • a communication utility 304 of the phone device 302 e.g., cellular RF unit in a mobile phone or a cable in a telephone
  • the processor 108 is connected to the loudspeakers to supply thereto digital data components (signals) OD(A)-OD D > resulting from processing the input collected signal ID, and is connected to the microphones to receive digital data components (signals) DD( A )- ⁇ (D) representative of the audio collected signals that are to be processed.
  • the output signals of both kinds i.e., OD and OD( A )-OD (D )
  • ED and ED(A)-ED D are obtained by applying a wavelet packet transform model to the processor's input, i.e., ED and ED(A)-ED D ), and are characterized by the signal shape corresponding to the maximal energy direction, i.e., a direction to or from the subject location.
  • the loudspeakers are associated with a D/A converter 212 connected to the processor 108.
  • an A/D converter 112 is interconnected between the processor 108 and the microphone assembly 106.
  • the second part of the direction finding utility 110 which generates a control signal CS to be reflected as a response CSws by the unit HOB, is implemented within the loudspeaker/microphone assembhes operable by the processor 108.
  • Fig. 4 exemplifies the initial stage in the method of the present invention aimed at deterrninrng the relative location of the authorized person (who carried the retro-directive unit) relative to the system 300, i.e. determining a desired location for signal transmission/reception.
  • the processor actuates at least one loudspeaker to transmit a control audio signal (step A) to thereby cause a response signal reflected from the unit HOB, and the microphones receive the response signal (step B).
  • the processor now processes the response signal, namely its four components collected by the four microphones, respectively (step C).
  • the processor 108 utilizes reference data stored in its memory and representative of a selected wavelet packet farnily to use it for processing the response signal, as will be described further below.
  • the result of the processing is indicative of a desired direction for signal transmission/reception, namely, is indicative of an optimal shape of a signal to be produced by the processor.
  • This shape is such that the maximal energy component of the signal is that associated with the desired direction.
  • the person may actuate the processor (e.g., by pressing a specific button on the phone system and start speaking) to thereby enable identification of his/her location (direction) and his/her audio signature for selecting the preferred wavelet packet family to be used for processing input and output signals.
  • the processor e.g., by pressing a specific button on the phone system and start speaking
  • identification of his/her location (direction) and his/her audio signature for selecting the preferred wavelet packet family to be used for processing input and output signals.
  • the following is the description of the Beam Forming algorithms used in the system of the present invention. As indicated above, the same algorithm can be used for direction finding as well.
  • the processing utilizes the so-called Beam Forming utility, which may be realized in general in software or/and in hardware.
  • the beam forming algorithm is essentially destined to shape a signal in accordance with a desired angular distribution of energy in the signal, and consists of applying the so-called software filtering to the input digital signal to produce an output shaped digital signal.
  • the algorithm utilizes the principles of Acoustic Phased Array transmission and wavelet transform theory More specifically, the algorithm utilizes processing of several signal components by applying a wavelet packet transform model to thereby produce phased array transmission reception inJfrom a predetermine direction.
  • the wavelet transform theory is known to be a powerful tool for exploring quasi-stationary signals.
  • the wavelet analysis extracts such essential features as frequency bands, including the characteristic frequencies of a signal. Operating with frequency bands instead of individual frequencies has significant advantages when dealing with signals continuously varying in time or transient signals.
  • Wavelet Packet Transform (WPT) to a signal f(t) of length 2 J generates a decomposition of the signal into a sum of n waveforms:
  • the transform involves (m+l) waveforms, whose spectra cover the whole frequency domain, and splits the spectra in a logarithmic manner.
  • Each decomposition block is linked to a certain frequency band.
  • ⁇ L is a waveform from a specific
  • the coefficients (p are the relative weights of each waveform, respectively.
  • the input signal ED received by the microphone assembly can be generally expressed in terms of WPT as follows:
  • tTM is the time delay introduced by the wavelet-based proces ssiinngg ttoo t thhee ssiiggnnaall rreecceeiivveedd bbyy tthhee mm mmii ⁇ crophone, and is defined as a function of the elevation angle to the source ⁇ (subject):
  • the "energy” of the received signal which is the sum of the “energys” of all the sub-signals at all the microphones in the assembly, is dependent on the elevation angle ⁇ or the azimuth angle ⁇ to the signal source (subject location), in the linear and circular arrays, respectively.
  • the direction to the subject location defined by the angle ⁇ o or ⁇ o is determined by optin- ⁇ zing the expression of the total "energy" of the received beams,
  • the family of waveforms ⁇ L could be chosen from a variety of known wavelet farnilies, such as the spline, Haar and Coifinan famihes.
  • preliminary tests are to be apphed to the voice of an authorized person ("the system owner") to enable fitting typical persons' voice with the best wavelet family, i.e., to select that wavelet family provichhg the best optimization possibilities of the system.
  • waveforms can be stored as reference data in the system (processor's memory) to better optimize the system's performance.
  • one wavelet family may be found to be the best fit for most personal audio samples, e.g., the spline wavelet family, thus may suffice for practical use.
  • the present invention can be used with an acoustic signal receiver device, such as a personal computer, to allow voice operation of a specific software application, with an acoustic signals ttansmitter device, such as TV or radio set, as well as a system intended for both transmission and reception of acoustic signals, such as a phone device, computer device, etc.
  • an acoustic signal receiver device such as a personal computer
  • an acoustic signals ttansmitter device such as TV or radio set
  • a system intended for both transmission and reception of acoustic signals such as a phone device, computer device, etc.
  • the present invention utilizes data indicative of a deshed drrection for signal transmission/reception, which can be obtained either by using suitable known means for identifying the subject location (e.g., acoustic retro- directive elements), and/or by using the wavelet-based processing of the input acoustic signal.
  • suitable known means for identifying the subject location e.g., acoustic retro- directive elements
  • wavelet-based processing of the input acoustic signal e.g., acoustic retro- directive elements

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)

Abstract

La présente invention concerne un procédé et un système permettant de mettre en oeuvre au moins un des procédés suivants : un procédé de transmission de signaux sonores à partir d'un réseau de transmission sonore dans le sens souhaité en direction de l'emplacement d'un sujet ; et un procédé de réception de signaux sonores se propageant dans un sens souhaité à partir de l'emplacement d'un sujet à l'aide d'un réseau de réception sonore. Des données indiquant le sens souhaité sont fournies et utilisées pour traiter les signaux recueillis devant être émis sous forme de signaux sonores par le réseau de transmission, et/ou pour traiter les signaux recueillis par le réseau de transmission. Le traitement se fonde sur un modèle choisi de transformée par paquets d'ondelettes. Un signal de sortie provenant du traitement est formé de manière que l'énergie maximale du signal de sortie soit sensiblement celle du sens souhaité.
EP02707081A 2001-03-22 2002-03-21 Procede et systeme de transmission et/ou de reception de signaux audio dans le sens souhaite Withdrawn EP1410678A2 (fr)

Applications Claiming Priority (3)

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US27761101P 2001-03-22 2001-03-22
US277611P 2001-03-22
PCT/IL2002/000234 WO2002078390A2 (fr) 2001-03-22 2002-03-21 Procede et systeme de transmission et/ou de reception de signaux audio dans le sens souhaite

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EP1410678A2 true EP1410678A2 (fr) 2004-04-21

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EP (1) EP1410678A2 (fr)
AU (1) AU2002241233A1 (fr)
WO (1) WO2002078390A2 (fr)

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US7346315B2 (en) 2004-03-30 2008-03-18 Motorola Inc Handheld device loudspeaker system
CA2765116C (fr) 2009-06-23 2020-06-16 Nokia Corporation Procede et appareil de traitement de signaux audio
DE102009032057A1 (de) * 2009-07-07 2011-01-20 Siemens Aktiengesellschaft Druckwellen-Aufnahme und Wiedergabe
CN110148401B (zh) * 2019-07-02 2023-12-15 腾讯科技（深圳）有限公司 语音识别方法、装置、计算机设备及存储介质

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US4586195A (en) * 1984-06-25 1986-04-29 Siemens Corporate Research & Support, Inc. Microphone range finder
US6535610B1 (en) * 1996-02-07 2003-03-18 Morgan Stanley & Co. Incorporated Directional microphone utilizing spaced apart omni-directional microphones
DE19841166A1 (de) * 1998-09-09 2000-03-16 Deutsche Telekom Ag Verfahren zur Kontrolle der Zugangsberechtigung für die Sprachtelefonie an einem Festnetz- oder Mobiltelefonanschluß sowie Kommunikationsnetz

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See references of WO02078390A3 *

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WO2002078390A3 (fr) 2004-02-19
WO2002078390A2 (fr) 2002-10-03
AU2002241233A1 (en) 2002-10-08

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