NOISE REDUCTION AND SPEECH ENHANCEMENT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority and benefit from United States provisional patent application number 62/075,967, filed on November 6, 2014, which is incorporated herein by reference in its entirety. This application further claims priority and benefit from United States patent application number 14/608,372, filed on January 29, 2015, which is incorporated herein by reference in its entirety. FIELD OF THE INVENTION

[0002] The present invention generally relates to methods and systems for reducing noise from acoustic signals and/or audio signals; and more particularly to methods and systems for reducing noise from acoustic signals and/or audio signals for the purpose of speech detection and enhancement. BACKGROUND OF THE INVENTION

[0003] Various types of electronic devices utilize acoustic microphones in order to capture acoustic signals. For example, a cellular phone, a smartphone, and a laptop computer typically include a microphone able to capture acoustic signals. Unfortunately, such microphones typically also capture noises and/or interference, in addition to or instead of capturing a desired acoustic signal (e.g., speech of a speaking person).

SUMMARY OF THE INVENTION

[0004] According to some embodiments of the invention, there is provided a method of reducing noise from acoustic signals and/or audio signals, and/or producing enhanced speech data associated therewith. In some embodiments, the method comprises, for example: (a) receiving distant (or distal) signal data from at least one distant (or distal) acoustic sensor or audio sensor or acoustic microphone; (b) receiving proximate (or proximal) signal data of the same time domain, from at least one other proximate (or proximal) acoustic sensor (or audio sensor, or acoustic microphone) which is located closer to a speaker than the at least one distant acoustic sensor; (c) receiving optical data of the same time domain, originating from at least one optical sensor (e.g., optical microphone, laser microphone, laser-based microphone) configured for optically detecting acoustic signals in an area (e.g., spatial area or spatial region, or spatial vicinity, or estimated spatial vicinity) of the speaker, and outputting data associated with speech of the speaker; (d) processing the distant signal data and the proximate signal data, and producing a speech reference and a noise reference of the time domain; (e) automatically operating an adaptive noise estimation module (or automatically executing an adaptive noise estimation process), which uses at least one adaptive filter for updating and/or improving accuracy of the noise reference, by identification of stationary and transient noise by using the optical data in addition to the proximate and distant signal data for outputting an updated noise reference; and (f) producing an enhanced speech data by deducting the updated noise reference from the speech reference.

[0005] According to some embodiments of the present invention, the optical data is indicative of speech and non-speech and/or voice activity related frequencies of the acoustic signal as detected by the at least one optical sensor. For instance, the optical data is indicative of voice activity and pitch of the speaker's speech, wherein the optical data is obtained by using voice activity detection (VAD) and/or pitch detection processes, or other suitable processes.

[0006] In some embodiments, the method further comprises, optionally: operating a post filtering module, configured for further reducing residual-noise components and for updating the at least one adaptive filter used by the adaptive noise estimation module; such that, for example, the post filtering module receives the optical data and processes it to identify transient noise by identification of speech and non-speech and/or voice activity related frequencies of the acoustic signal as detected by the at least one optical sensor.

[0007] Additionally or alternatively to the above, the method optionally comprises: a preliminary stationary noise reduction process, comprising: detecting stationary noise at the proximate and distant acoustic sensors; and reducing stationary noise from the proximate signal data and distant signal data. For example, the preliminary stationary noise reduction process may be performed before step (d) of processing of the distant and proximate signal data. Other suitable order(s) of execution may be used. [0008] Optionally, the preliminary stationary noise reduction process is carried out using at least one speech probability estimation process. In some embodiments, the preliminary stationary noise reduction process is carried out using optimal modified mean-square error Log-spectral amplitude (OMLSA) based algorithm or process.

[0009] Optionally, the speech reference is produced by superimposing the proximate data to the distant data; and the noise reference is produced by subtracting the distant data from the proximate data.

[0010] Additionally or alternatively, the method further comprises operating a short term Fourier transform (STFT) operator over the noise and speech references, wherein the adaptive noise reduction module uses the transformed references for the noise reduction process; and inversing the transformation using inverse STFT (ISTFT) for producing the enhanced speech data.

[0011] Optionally, the method further comprises: outputting an enhanced acoustic signal using the enhanced speech data, which is a noise-reduced speech acoustic signal, using at least one audio output device (e.g., audio speaker, audio earphones, or the like).

[0012] Additionally or alternatively, some or all the steps of the method are carried out in real time or near real time, or substantially in real time; such that, for example, noise is cleaned or mitigated or removed while the speaker talks, or concurrently or simultaneously while the speaker talks.

[0013] According to some embodiments of the invention, there is provided a system for reducing noise from acoustic signals for producing enhanced speech data associated therewith, wherein the system comprises, for example: (a) at least one distant acoustic sensor or microphone, outputting distant signal data; (b) at least one other proximate acoustic sensor or microphone, located closer to a speaker than the at least one distant acoustic sensor, the proximate acoustic sensor outputs proximate signal data; (c) at least one optical sensor (e.g., laser microphone, laser-based microphone, optical microphone) configured for optically detecting acoustic signals in an area (or vicinity, or estimated location) of the speaker and outputting optical data associated therewith; and (d) at least one processor or controller or CPU or DSP or Integrated Circuit (IC) or logic unit, operating modules configured for processing received data from the acoustic and optical sensors for enhancing speech of a speaker in the area thereof. [0014] In some embodiments, the processor (or other suitable module or unit) operates modules which may be configured for: (i) receiving proximate data, distant data and optical data from the acoustic and optical sensors; (ii) processing the distant signal data and the proximate signal data for producing a speech reference and a noise reference of the time domain; (iii) operating an adaptive noise estimation module, which uses at least one adaptive filter for updating and improving accuracy of the noise reference by identification of stationary and transient noise by using the optical data in addition to the proximate and distant signal data for outputting an updated noise reference; and (iv) producing an enhanced speech data by deducting the updated noise reference from the speech reference.

[0015] Optionally, the at least one proximate acoustic sensor comprises a microphone; and the at least one distant acoustic sensor comprises a microphone.

[0016] Additionally or alternatively, the at least one optical sensor comprises a coherent light source or coherent laser source; and at least one optical detector for detecting vibrations of the speaker related to the speaker's speech through detection of reflection of transmitted coherent light beams or coherent laser beams.

[0017] In some embodiments, the acoustic proximate and distant sensors and the at least one optical sensor are positioned such that each is directed to the speaker, or towards the speaker, or towards the general location or general vicinity of the speaker, or towards the estimated vicinity of the speaker.

[0018] Optionally, the optical data is indicative of speech and non-speech and/or voice activity related frequencies of the acoustic signal as detected by the optical sensor. The optical data may specifically be indicative of voice activity and pitch of the speaker's speech; the optical data may be obtained by using voice activity detection (VAD) and/or pitch detection processes.

[0019] The system optionally further comprises a post filtering module, configured for identifying residual noise and updating the at least one adaptive filter used by the adaptive noise estimation module; for example, by receiving the optical data and processing it to identify transient noise by identification of speech and non-speech and/or voice activity related frequencies of the acoustic signal as detected by the optical sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Fig. 1 is a schematic illustration of a system for noise reduction and speech enhancement having one proximate microphone, one distant microphone and one optical sensor located in a predefined area of a speaker, according to some embodiments of the invention.

[0021] Fig. 2 is a block diagram schematically illustrating the operation of the system, according to some embodiments of the invention.

[0022] Fig. 3 is a flowchart, schematically illustrating a process of noise reduction and speech enhancement, according to some embodiments of the invention. DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

[0023] In the following detailed description of various embodiments, reference is made to the accompanying drawings that form a part thereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0024] The present invention, in some embodiments thereof, provides systems and methods, which use auxiliary one or more non-contact optical sensors for improved noise reduction and speech recognition. For example, the present invention may utilize optical sensor(s) or optical microphone(s) or laser microphone(s), which may not be in contact with the speaker's body or face, and which may be located away from or remotely from the speaker's body or face. The speech enhancement process(es) of the present invention efficiently uses multiple acoustic sensors such as acoustic microphones located in a predefined area of a speaker at different distances in respect to the speaker and one or more optical sensors located in proximity to the speaker, yet not necessarily in contact with the speaker's skin, for improved noise reduction and speech recognition. In some embodiments, the output of this noise reduction and speech enhancement process is an enhanced noise-reduced acoustic signal data indicative of speech of the speaker.

[0025] The data from the acoustic sensors is first processed to create speech and noise references and the references are used in combination with data from the optical sensor to perform an advanced noise reduction and speech recognition to output data indicative of a significantly noise-reduced acoustic signal representing only the speech of the speaker.

[0026] Reference is now made to Fig. 1, schematically illustrating a system 100 for noise reduction and speech enhancement of speech acoustic signals originating from a speaker 10 in a predefined area, according to some embodiments of the invention. The system 100 uses at least three sensors: at least one proximate acoustical sensor such as a proximate microphone 112 preferably located in proximity to the speaker 10, at least one distant acoustical sensor such as a distant microphone 111 located at larger distance from the speaker 10 than the proximate microphone 112, and at least one optical sensor unit 120 such as an optical microphone, which is preferably directed to the speaker 10. The system 100 additionally comprises one or more processors such as processor 110 for receiving and processing the data arriving from the distant and proximate microphones 111 and 112, respectively, and from the optical sensor unit 120 to output a dramatically noise-reduced audio signal data which is an enhanced speech data of the speaker 10. This means that the system 100 is configured mainly for enhancing speaker's speech related signals by operating one or more highly advanced noise reduction and voice activity detection (VAD) processes using the data from the sensors of 111, 112 and 120 and using the relative localization of the acoustic sensors 111 and 112.

[0027] According to some embodiments, the optical sensor unit 120 is configured for optically measuring and detecting speech related acoustical signals and output data indicative thereof. For example, a laser based optical microphone having a coherent source and an optical detector with a processor unit enabling extracting the audio signal data using extraction techniques such as vibrometry based techniques such as Doppler based analysis or interference patterns based techniques. The optical sensor, in some embodiments, transmits a coherent optical signal towards the speaker and measures the optical reflection patterns reflected from the vibrating surfaces of the speaker. Any other sensor type and technique may be used for optically establishing the speaker(s)'s audio data.

[0028] In some embodiments the sensor unit 120 comprises a laser based optical source and an optical detector and merely outputs a raw optical signal data indicative of detected reflected light from the speaker or other reflecting surfaces. In these cases, the data is further processed at the processor 110 for deducing speech signal data from the optical sensor e.g. by using speech detection and VAD processes (e.g. by identification of speaker's voice pitches). In other cases the sensor unit includes a processor that allows carrying out at least part of the processing of the detector's output signals. In both cases the optical sensor unit 120 allows deducing a speech related optical data shortly referred to herein as "optical data".

[0029] The output signal from the distant and proximate sensors e.g. from the distant and proximate microphones 111 and 112, respectively, may first be processed through a preliminary noise-reduction process. For example, a stationary noise- reduction process may be carried out to identify stationary noise components and reducing them from the output signals of each acoustic sensor (e.g. microphones 111 and 112). In other embodiments, the stationary noise may be identified and reduced by using one or more speech probability estimation processes such as optimal modified mean-square error Log-spectral amplitude (OMLSA) algorithms or any other noise reduction technique for acoustic sensors output known in the art.

[0030] The distant and proximate sensors' audio data (whether improved by the initial noise reduction process or the raw output signal of the sensors), shortly referred to herein as the distant audio data and proximate audio data, respectively, are processed to produce: a speech reference, which is a data packet such as an array or matrix indicative of the speech signal; and a noise reference, which is a data packet such as an array or matrix indicative of the speech signal of the same time domain as that of the speech signal.

[0031] The noise reference is then further processed and improved through an adaptive noise estimation module and the improved noise reference is then used along with the data from the optical unit 120 to further reduce noise from the speech reference using a post filtering module to output an enhanced speech data. The enhanced speech data can be outputted as an enhanced speech audio signal using one or more audio output devices such as a speaker 30.

[0032] According to some embodiments of the invention, the processing of the output signals of the sensors 111, 112 and 120 may be carried out in real time or near real time through one or more designated computerized systems in which the processor is embedded and/or through one or more other hardware and/or software instruments.

[0033] Fig. 2 is a block diagram schematically illustrating the algorithmic operation of the system, according to some embodiments of the invention. The process comprises four main parts: (i) a pre-processing part that slightly enhances the data originating from the distant and proximate microphones (Block 1) and extracts voice- activity detection (VAD) and pitch information from the optical sensor (Block 2); (ii) generation of a speech- and noise-reference signals (Blocks 3 and 4, respectively); (iii) adaptive-noise estimation (Block 5); and (iv) post-filtering procedure (Block 6) with post-filtering optionally using filtering techniques as described in Cohen et al., 2003 A.

[0034] According to some embodiments, the output from the two acoustic sensors (proximate microphone 12 output thereof represented by z (n) and distant microphone 11 output thereof represented by z ₂ (n)) are first enhanced by a preliminary noise- reduction process (Block 1) using one or more noise reduction algorithms 11a and 12a operating blocks 3 and 4 for creating a speech reference and a noise reference from the initially noise-reduced outputs of the distant and proximate microphones 11 and 12. The speech reference is denoted by y(n) and the noise reference by u(n). These references (outputted as signals or data packets for instance) are further transformed to the time- frequency domain e.g. by using the short-time Fourier transform (STFT) operator 15/16. The transformed output of the noise reference signal is indicated by U(k,l). The transformed noise reference U(k,l) is further processed through an adaptive noise-estimation operator or module 17 to further suppress stationary and transient noise components from the transformed speech reference to output an initially enhanced speech reference Y(k,l). The speech reference transformed signal Y(k, l) is finally post-filtered by Block 6 using a post filtering module 18 using optical data from the optical sensor unit 20 to reduce residual noise components from the transformed speech reference. This block also incorporates information from the optical sensor unit such as VAD and pitch estimation, derived in Block 2 optionally for identification of transient (non- stationary) noise and speech detection. Accordingly, some hypothesis- testing is carried out in Block 6 to determine which category (stationary noise, transient noise, speech) a given time-frequency bin belongs to. These decisions are also incorporated into the adaptive noise-estimation process (Block 5) and the reference signals generation (Blocks 3-4). For instance, the optically-based hypothesis decisions are used as a reliable time-frequency VAD for improved extraction of the reference signals and estimation of the adaptive filters related to stationary and transient noise components. The resulting enhanced speech audio signal is finally transformed to the time domain via the inverse-STFT (ISTFT) 19, yielding x(n). In the next subsections, each block will be briefly explained.

[0035] Block 1 : Stationary-noise reduction: In the first step of the algorithm, the pre-processing step, the proximate- and distant- microphone signals are slightly enhanced by suppressing stationary-noise components. This noise suppression is optional and may be carried out by using conventional OMLSA algorithmic such as described in Cohen et al., 2001. Specifically, a spectral-gain function is evaluated by minimizing the mean-square error of the log-spectra, under speech-presence uncertainty. The algorithm employs a stationary-noise spectrum estimator, obtained by the improved minima controlled recursive averaging (IMCRA) algorithm such as described in Cohen et al., 2003B, as well as signal to noise ratio (SNR) and speech- probability estimators for evaluating the gain function. The enhancement-algorithm parameters are tuned in a way that noise is reduced without compromising for speech intelligibility. This block functionality is required for successively producing reliable speech- and noise- reference signals for Blocks 3 and 4.

[0036] Block 2: VAD and Pitch Extraction: This block, a part of the pre-processing step, attempts to extract as much information as possible from the output data of the optical unit 20. Specifically, according to some embodiments, the algorithm inherently assumes the optical signal is immune to acoustical interferences and detects the desired-speaker's pitch frequency by searching for spectral harmonic patterns using for example a technique described in Avargel et al., 2013. The pitch tracking is accomplished by an iterative dynamic -programming-based algorithm, and the resulting pitch is finally used to provide soft-decision voice-activity detection (VAD).

[0037] Block 3: Speech-reference signal generation: According to some embodiments, this block is configured for producing a speech-reference signal by nulling-out coherent- noise components, coming from directions that differ from that of the desired speaker. The block consists of a possible different superposition of outputs or improved outputs (after preliminary stationary noise reduction) originating from the proximate and distant microphones 12 and 11, respectively, like beam forming, proximate-cardioid, proximate super-cardioid, and etc.

[0038] Block 4: Noise -reference signal generation: This block aims at producing a noise-reference signal by nulling-out coherent-speech components, coming from the desired speaker directions, for example by making use of appropriate delay and gain, the distant-cardioid polar pattern can be generated (see Chen et al., 2004). Consequently, the noise-reference signal may consist mostly of noise.

[0039] Block 5: Adaptive-noise estimation: This block is utilized in the STFT domain and is configured for identifying and eliminating both stationary and transient noise components that leak through the side-lobes of the fixed beam-forming (Block 3). Specifically, at each frequency bin, two or more sets of adaptive filters are defined: a first set of filters corresponds to the stationary-noise components, whereas the second set of filters is related to transient (non-stationary) noise components. Accordingly, these filters are adaptively updated based on the estimated hypothesis (stationary or transient; derived in Block 6), using the normalized least mean square (NLMS) algorithm. The output of these sets of filters is then subtracted from the speech reference signal at each individual frequency, yielding the partially or initially- enhanced speech reference signal Y(k, 1) in the STFT domain.

[0040] Block 6: Post-filtering: this module is used to reduce residual noise components by estimating a spectral-gain function that minimizes the mean-square error of the log-spectra, under speech-presence uncertainty (see Cohen et al., 2003B). Specifically, this block uses the ratio between the improved speech-reference signal (after adaptive filtering) and noise-reference signal in order to properly distinguish between each of the hypotheses - stationary noise, transient noise, and desired speech - at a given time-frequency domain. To attain a more reliable hypothesis decision, a priori speech information (activity detection and pitch frequency) from the optical signal (Block 2) is also incorporated. This hypothesis testing, combined with the optical information, is employed to attain an efficient SNR and speech-probability estimators, as well as background noise power spectral density (PSD) estimation (for both stationary and transient components). The resulting estimators are then used in evaluating the optimal spectral-gain G(k, 1), which in turns yields the clean desired- speaker's STFT estimator via:

[0041] Finally, applying the inverse STFT (ISTFT), we obtain the time-domain desired speaker estimator x(n) , which is indicative of the enhanced audio signal data of the speech of the speaker. [0042] Reference is now made to Fig. 3, which is a flowchart schematically illustrating a method for noise reduction and speech enhancement, according to some embodiments of the invention. The process includes the steps of: receiving data/signals from a distant acoustic sensor 31a, receiving data/signals from a proximate acoustic sensor 31b and receiving data/signals from an optical sensor unit 31c all indicative of acoustics of a predefined area for detection of a speaker's speech, wherein the distant acoustic sensor is located at a farther distance from the speaker than the proximate acoustic sensor. Optionally, the acoustic sensors' data is processed through a preliminary noise reduction process as illustrated in steps 32a and 32b, e.g. by using stationary noise reduction operators such as OMLSA.

[0043] The raw signals from the acoustic sensors or the stationary noise reduced signals originating from the acoustic sensors are then processed to create a noise reference and a speech reference 33. Both sensors' data is taken into consideration for calculation of each reference. For example, to calculate the speech reference signal, the proximate and distant sensors are properly delayed and summed such that noise components from directions that differ from that of the desired speaker are substantially reduced. The noise reference is generated in a similar manner with the only difference being that the coherent speaker is now to be excluded by proper gains and delays of the proximate and distant sensors.

[0044] Optionally, the noise and speech reference signals are transformed to the frequency domain e.g. via STFT 34 and the transformed signals data referred to herein as speech data and noise data are further processed for refining the noise components identification e.g. for identifying non- stationary (transient) noise components as well as additional stationary noise components using an adaptive noise estimation module (e.g. algorithm) 35. The adaptive noise estimation module uses one or more filters to calculate the additional noise components such a first filter which calculates the stationary noise components and a second filter that calculates the non-stationary transient noise components using the noise reference data (i.e. the transformed noise reference signal) in a calculation algorithmic that can be updated by a post filtering module that takes into account the optical data from the optical unit 31c and the speech reference data. The additional noise components are then filtered out to create a partially enhanced speech reference data 36. [0045] The partially enhanced speech reference data is further processed through a post filtering module 37, which uses optical data originating from the optical unit. In some embodiments, the post filtering module is configured for receiving speech identification 31c (such as speaker's pitch identification) and VAD information from the optical unit or for identifying speech and VAD components using raw sensor data originating from the detector of the optical unit. The post filtering module is further configured for receiving the speech reference data (i.e. the transformed speech reference) and enhancing thereby the identification of speech related components.

[0046] The post filtering module ultimately calculates and outputs a final speech enhanced signal 37 and optionally also updates the adaptive noise estimation module for the next processing of the acoustic sensors data 38 relating to the specific area and speaker therein.

[0047] The above-described process of noise reduction and speech detection for producing enhanced speech data of a speaker may be carried out in real time or near real time.

[0048] The present invention may be implemented in other speech recognition systems and methods such as for speech content recognition algorithms i.e. words recognition and the like and/or for outputting a cleaner audio signal for improving the acoustic quality of the microphones output using an acoustic/audio output device such as one or more audio speakers.

[0049] In some embodiments of the present invention, only "safe" laser beams or sources may be used; for example, laser beam(s) or source(s) that are known to be non- damaging to human body and/or to human eyes, or laser beam(s) or source(s) that are known to be non-damaging even if accidently hitting human eyes for a short period of time. Some embodiments may utilize, for example, Eye-Safe laser, infra-red laser, infra-red optical signal(s), low-strength laser, and/or other suitable type(s) of optical signals, optical beam(s), laser beam(s), infra-red beam(s), or the like. It would be appreciated by persons of ordinary skill in the art, that one or more suitable types of laser beam(s) or laser source(s) may be selected and utilized, in order to safely and efficiently implement the system and method of the present invention.

[0050] In some embodiments, the optical microphone (or optical sensor) and/or its components may be implemented as (or may comprise) a Self-Mix module; for example, utilizing a self-mixing interferometry measurement technique (or feedback interferometry, or induced-modulation interferometry, or backscatter modulation interferometry), in which a laser beam is reflected from an object, back into the laser. The reflected light interferes with the light generated inside the laser, and this causes changes in the optical and/or electrical properties of the laser. Information about the target object and the laser itself may be obtained by analyzing these changes.

[0051] The present invention may be utilized in, or with, or in conjunction with, a variety of devices or systems that may benefit from noise reduction and/or speech enhancement; for example, a smartphone, a cellular phone, a cordless phone, a video conference system, a landline telephony system, a cellular telephone system, a voice- messaging system, a Voice-over-IP system or network or device, a vehicle, a vehicular dashboard, a vehicular audio system or microphone, a dictation system or device, Speech Recognition (SR) device or module or system, Automatic Speech Recognition (ASR) module or device or system, a speech-to-text converter or conversion system or device, a laptop computer, a desktop computer, a notebook computer, a tablet, a phone- tablet or "phablet" device, a gaming device, a gaming console, a wearable device, a smart-watch, a Virtual Reality (VR) device or helmet or glasses or headgear, an Augmented Reality (AR) device or helmet or glasses or headgear, a device or system or module that utilizes speech-based commands or audio commands, a device or system that captures and/or records and/or processes and/or analyzes audio signals and/or speech and/or acoustic signals, and/or other suitable systems and devices.

[0052] In some embodiments of the present invention, the laser beam or optical beam may be directed to an estimated general-location of the speaker; or to a predefined target area or target region in which a speaker may be located, or in which a speaker is estimated to be located. For example, the laser source may be placed inside a vehicle, and may be targeting the general location at which a head of the driver is typically located. In other embodiments, a system may optionally comprise one or more modules that may, for example, locate or find or detect or track, a face or a mouth or a head of a person (or of a speaker), for example, based on image recognition, based on video analysis or image analysis, based on a pre-defined item or object (e.g., the speaker may wear a particular item, such as a hat or a collar having a particular shape and/or color and/or characteristics), or the like. In some embodiments, the laser source(s) may be static or fixed, and may fixedly point towards a general-location or towards an estimated-location of a speaker. In other embodiments, the laser source(s) may be non-fixed, or may be able to automatically move and/or change their orientation, for example, to track or to aim towards a general-location or an estimated- location or a precise-location of a speaker. In some embodiments, multiple laser source(s) may be used in parallel, and they may be fixed and/or moving.

[0053] In some embodiments, the system and method may efficiently operate at least during time period(s) in which the laser beam(s) or the optical signal(s) actually hit (or reach, or touch) the face or the mouth or the mouth-region of a speaker. In some embodiments, the system and/or method need not necessarily provide continuous speech enhancement or continuous noise reduction; but rather, in some embodiments the speech enhancement and/or noise reduction may be achieved in those time-periods in which the laser beam(s) actually hit the face of the speaker. In other embodiments, continuous or substantially-continuous noise reduction and/or speech enhancement may be achieved; for example, in a vehicular system in which the laser beam is directed towards the location of the head or the face of the driver.

[0054] Although portions of the discussion herein relate, for demonstrative purposes, to wired links and/or wired communications, some embodiments are not limited in this regard, and may include one or more wired or wireless links, may utilize one or more components of wireless communication, may utilize one or more methods or protocols of wireless communication, or the like. Some embodiments may utilize wired communication and/or wireless communication.

[0055] The system(s) of the present invention may optionally comprise, or may be implemented by utilizing suitable hardware components and/or software components; for example, processors, CPUs, DSPs, circuits, Integrated Circuits, controllers, memory units, storage units, input units (e.g., touch-screen, keyboard, keypad, stylus, mouse, touchpad, joystick, trackball, microphones), output units (e.g., screen, touch-screen, monitor, display unit, audio speakers), wired or wireless modems or transceivers or transmitters or receivers, and/or other suitable components and/or modules. The system(s) of the present invention may optionally be implemented by utilizing co- located components, remote components or modules, "cloud computing" servers or devices or storage, client/server architecture, peer-to-peer architecture, distributed architecture, and/or other suitable architectures or system topologies or network topologies. [0056] Calculations, operations and/or determinations may be performed locally within a single device, or may be performed by or across multiple devices, or may be performed partially locally and partially remotely (e.g., at a remote server) by optionally utilizing a communication channel to exchange raw data and/or processed data and/or processing results.

[0057] Functions, operations, components and/or features described herein with reference to one or more embodiments of the present invention, may be combined with, or may be utilized in combination with, one or more other functions, operations, components and/or features described herein with reference to one or more other embodiments of the present invention. The present invention may thus comprise any possible or suitable combinations, re-arrangements, assembly, re-assembly, or other utilization of some or all of the modules or functions or components that are described herein, even if they are discussed in different locations or different chapters of the above discussion, or even if they are shown across different drawings or multiple drawings.

[0058] Some embodiments of the present invention may utilize, or may comprise, or may be used in association with or in conjunction with, one or more devices, systems, units, algorithms, methods and/or processes, which are described in any of the following references: [1]. M. Graciarena, H. Franco, K. Sonmez, and H. Bratt, "Combining standard and throat microphones for robust speech recognition," IEEE Signal Process. Lett., vol. 10, no. 3, pp. 72-74, Mar. 2003. [2]. T. Dekens, W. Verhelst, F. Capman, and F. Beaugendre, "Improved speech recognition in noisy environments by using a throat microphone for accurate voicing detection," in 18th European Signal Processing Conf. (EUSIPCO), Aallborg, Denmark, Aug. 2010, pp. 23-27. [3]. Y. Avargel and I. Cohen, "Speech measurements using a laser Doppler vibrometer sensor: Application to speech enhancement," in Proc. Hands-free speech comm. and mic. Arrays (HSCMA), Edingurgh, Scotland, May 2011 A. [4]. Y. Avargel, T. Bakish, A. Dekel, G. Horovitz, Y. Kurtz, and A. Moyal, "Robust Speech Recognition Using an Auxiliary Laser-Doppler Vibrometer Sensor," in Proc. Speech Process, Conf., Tel- Aviv, Israel, , June 2011 B. [5] Y. Avargel and Tal Bakish, "System and Method for Robust Estimation and Tracking the Fundamental Frequency of Pseudo Periodic Signals in the Presence of Noise," US/2013/0246062 Al, 2013. [6] T. Bakish, G. Horowitz, Y. Avargel, and Y. Kurtz, "Method and System for Identification of Speech Segments,"US2014/0149117 Al, 2014. [7]. I. Cohen, S. Gannot, and B. Berdugo, "An Integrated Real-Time Beamforming and Postfiltering System for Nonstationary Noise Environments," EURASIP Journal on Applied Signal Process., vol. 11 , pp. 1064-1073, Jan. 2003 A. [8]. I. Cohen and B. Berdugo, "Speech enhancement for nonstationary noise environment," Signal Process., vol. 81, pp. 2403-2418, Nov. 2001. [9]. I. Cohen, "Noise spectrum estimation in adverse environments: Improved minima controlled recursive averaging," IEEE Trans. Speech Audio Process., vol. 11, no. 5, pp. 466-475, Sep. 2003B.

[10] J. Chen, L. Shue, K. Phua, and H. Sun, "Theoretical Comparisons of Dual Microphone Systems," ICASSP, 2004.

[0059] While certain features of the present invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. Accordingly, the claims are intended to cover all such modifications, substitutions, changes, and equivalents.