Patent Publication Number: US-2023142711-A1

Title: Method and device for spectral expansion of an audio signal

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 16/783,624, filed 6 Feb. 2020, which is a continuation of and claims priority to U.S. patent application Ser. No. 16/047,612, which is a continuation of and claims priority to U.S. patent application Ser. No. 14/155,724 filed Jan. 15, 2014, now U.S. Pat. No. 10,043,535, which claims the benefit of U.S. Provisional Patent Application No. 61/752,569 filed Jan. 15, 2013 and further claims the benefit of U.S. Provisional Patent Application No. 61/920,321 filed Dec. 23, 2013. All of which are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to audio enhancement for automatically increasing the spectral bandwidth of a voice signal to increase a perceived sound quality in a telecommunication conversation. 
     BACKGROUND 
     Sound isolating (SI) earphones and headsets are becoming increasingly popular for music listening and voice communication. SI earphones enable the user to hear an incoming audio content signal (be it speech or music audio) clearly in loud ambient noise environments, by attenuating the level of ambient sound in the user ear-canal. 
     SI earphones benefit from using an ear canal microphone (ECM) configured to detect user voice in the occluded ear canal for voice communication in high noise environments. In such a configuration, the ECM detects sound in the users ear canal between the ear drum and the sound isolating component of the SI earphone, where the sound isolating component is, for example, a foam plug or inflatable balloon. The ambient sound impinging on the ECM is attenuated by the sound isolating component (e.g., by approximately 30 dB averaged across frequencies 50 Hz to 10 kHz). The sound pressure in the ear canal in response to user-generated voice can be approximately 70-80 dB. As such, the effective signal to noise ratio measured at the ECM is increased when using an ear canal microphone and sound isolating component. This is clearly beneficial for two-way voice communication in high noise environments: where the SI earphone wearer with ECM can hear the incoming voice signal reproduced with an ear canal receiver (i.e., loudspeaker), with the incoming voice signal from a remote calling party. Secondly, the remote party can clearly hear the voice of the SI earphone wearer with the ECM even if the near-end caller is in a noisy environment, due to the increase in signal-to-noise ratio as previously described. 
     The output signal of the ECM with such an SI earphone in response to user voice activity is such that high-frequency fricatives produced by the earphone wearer, e.g., the phoneme /s/, are substantially attenuated due to the SI component of the earphone absorbing the air-borne energy of the fricative sound generated at the user&#39;s lips. As such, very little user voice sound energy is detected at the ECM above about 4.5 kHz and when the ECM signal is auditioned it can sound “muffled”. 
     A number of related art discusses spectral expansion. Application US20070150269 describes spectral expansion of a narrowband speech signal. The application uses a “parameter detector” which for example can differentiate between a vowel and consonant in the narrowband input signal, and generates higher frequencies dependent on this analysis. 
     Application US20040138876 describes a system similar to US20070150269 in that a narrowband signal (300 Hz to 3.4 kHz) is analysis to determine in sibilants or non-sibilants, and high frequency sound is generated in the case of the former occurrence to generate a new signal with energy up to 7.7 kHz. 
     U.S. Pat. No. 8,200,499 describes a system to extend the high-frequency spectrum of a narrow-band signal. The system extends the harmonics of vowels by introducing a non-linearity. Consonants are spectrally expanded using a random noise generator. 
     U.S. Pat. No. 6,895,375 describes a system for extending the bandwidth of a narrowband signal such as a speech signal. The method comprises computing the narrowband linear predictive coefficients (LPCs) from a received narrowband speech signal and then processing these LPC coefficients into wideband LPCs, and then generating the wideband signal from these wideband LPCs 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  illustrates a wearable system for spectral expansion of an audio signal in accordance with an exemplary embodiment; 
         FIG.  1 B  illustrates another wearable system for spectral expansion of an audio signal in accordance with an exemplary embodiment; 
         FIG.  1 C  illustrates a mobile device for coupling with the wearable system in accordance with an exemplary embodiment; 
         FIG.  1 D  illustrates another mobile device for coupling with the wearable system in accordance with an exemplary embodiment; 
         FIG.  1 E  illustrates an exemplary earpiece for use with the enhancement system in accordance with an exemplary embodiment; 
         FIG.  2    illustrates flow chart for a method for spectral expansion in accordance with an embodiment herein; 
         FIG.  3    illustrates a flow chart for a method for generating a mapping or prediction matrix in accordance with an embodiment herein; 
         FIG.  4    illustrates use configurations for the spectral expansion system in accordance with an exemplary embodiment; and 
         FIG.  5    depicts a block diagram of an exemplary mobile device or multimedia device suitable for use with the spectral enhancement system in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Similar reference numerals and letters refer to similar items in the following figures, and thus once an item is defined in one figure, it may not be discussed for following figures. 
     In some embodiments, a system increases the spectral range of the ECM signal so that detected user-voice containing high frequency energy (e.g., fricatives) is reproduced with higher frequency content (e.g., frequency content up to about 8 kHz) so that the processed ECM signal can be auditioned with a more natural and “less muffled” quality. 
     “Voice over IP” (VOIP) telecommunications is increasingly being used for two-way voice communications between two parties. The audio bandwidth of such VOIP calls is generally up to 8 kHz. With a conventional ambient microphone as found on a mobile computing device (e.g., smart phone or laptop), the audio output is approximately linear up to about 12 kHz. Therefore, in a VOIP call between two parties using these conventional ambient microphones, made in a quiet environment, both parties will hear the voice of the other party with a full audio bandwidth up to 8 kHz. However, when an ECM is used, even though the signal to noise ratio improves in high noise environments, the audio bandwidth is less compared with the conventional ambient microphones, and each user will experience the received voice audio as sounding band-limited or muffled, as the received and reproduced voice audio bandwidth is approximately half as would be using the conventional ambient microphones. 
     Thus, embodiments herein expand (or extend) the bandwidth of the ECM signal before being auditioned by a remote party during high-band width telecommunication calls, such as VOIP calls. 
     The relevant art described above fails to generate a wideband signal from a narrowband signal based on a first analysis of a reference wideband speech signal to generate a mapping matrix (e.g., least-squares regression fit) that is then applied to a narrowband input signal and noise signal to generate a wideband output signal. 
     There are two things that are “different” about the approach in some of the embodiments described herein: One difference is that there is an intermediate approach between a very simple model (that the energy in the 3.5-4 kHz range gets extended to 8 kHz, say), and a very complex model (that attempts to classify the phoneme at every frame, and deploy a specific template for each case). Embodiments herein can have a simple, mode-less model, but where it has quite a few parameters, which can be learned from training data. The second significant difference is that the some of the embodiments herein use a “dB domain” to do the linear prediction. 
     Referring to  FIG.  1 A , a system  10  in accordance with a headset configuration is shown. In this embodiment, wherein the headset operates as a wearable computing device, the system  10  includes a first ambient sound microphone  11  for capturing a first microphone signal, a second ear canal microphone  12  for capturing a second microphone signal, and a processor  14 / 16  communicatively coupled to the second microphone  12  to increase the spectral bandwidth of an audio signal. As will be explained ahead, the processor  14 / 16  may reside on a communicatively coupled mobile device or other wearable computing device. 
     The system  10  can be configured to be part of any suitable media or computing device. For example, the system may be housed in the computing device or may be coupled to the computing device. The computing device may include, without being limited to wearable and/or body-borne (also referred to herein as bearable) computing devices. Examples of wearable/body-borne computing devices include head-mounted displays, earpieces, smartwatches, smartphones, cochlear implants and artificial eyes. Briefly, wearable computing devices relate to devices that may be worn on the body. Bearable computing devices relate to devices that may be worn on the body or in the body, such as implantable devices. Bearable computing devices may be configured to be temporarily or permanently installed in the body. Wearable devices may be worn, for example, on or in clothing, watches, glasses, shoes, as well as any other suitable accessory. 
     Although only the first  11  and second  12  microphone are shown together on a right earpiece, the system  10  can also be configured for individual earpieces (left or right) or include an additional pair of microphones on a second earpiece in addition to the first earpiece. 
     Referring to  FIG.  1 B , the system in accordance with yet another wearable computing device is shown. In this embodiment, the system is part of a set of eyeglasses  20  that operate as a wearable computing device, for collective processing of acoustic signals (e.g., ambient, environmental, voice, etc.) and media (e.g., accessory earpiece connected to eyeglasses for listening) when communicatively coupled to a media device (e.g., mobile device, cell phone, etc.). In one arrangement, analogous to an earpiece with microphones but further embedded in eyeglasses, the user may rely on the eyeglasses for voice communication and external sound capture instead of requiring the user to hold the media device in a typical hand-held phone orientation (i.e., cell phone microphone to mouth area, and speaker output to the ears). That is, the eyeglasses sense and pick up the user&#39;s voice (and other external sounds) for permitting voice processing. An earpiece may also be attached to the eyeglasses  20  for providing audio and voice. 
     In the configuration shown, the first  13  and second  15  microphones are mechanically mounted to one side of eyeglasses. Again, the embodiment  20  can be configured for individual sides (left or right) or include an additional pair of microphones on a second side in addition to the first side. 
       FIG.  1 C  depicts a first media device  14  as a mobile device (i.e., smartphone) which can be communicatively coupled to either or both of the wearable computing devices ( 10 / 20 ).  FIG.  1 D  depicts a second media device  16  as a wristwatch device which also can be communicatively coupled to the one or more wearable computing devices ( 10 / 20 ). As previously noted in the description of these previous figures, the processor for updating the adaptive filter is included thereon, for example, within a digital signal processor or other software programmable device within, or coupled to, the media device  14  or  16 . 
     With respect to the previous figures, the system  10  or  20  may represent a single device or a family of devices configured, for example, in a master-slave or master-master arrangement. Thus, components of the system  10  or  20  may be distributed among one or more devices, such as, but not limited to, the media device  14  illustrated in  FIG.  1 C  and the wristwatch  16  in  FIG.  1 D . That is, the components of the system  10  or  20  may be distributed among several devices (such as a smartphone, a smartwatch, an optical head-mounted display, an earpiece, etc.). Furthermore, the devices (for example, those illustrated in  FIG.  1 A  and  FIG.  1 B ) may be coupled together via any suitable connection, for example, to the media device in  FIG.  1 C  and/or the wristwatch in  FIG.  1 D , such as, without being limited to, a wired connection, a wireless connection or an optical connection. 
     The computing devices shown in  FIGS.  1 C and  1 D  can include any device having some processing capability for performing a desired function, for instance, as shown in  FIG.  5   . Computing devices may provide specific functions, such as heart rate monitoring or pedometer capability, to name a few. More advanced computing devices may provide multiple and/or more advanced functions, for instance, to continuously convey heart signals or other continuous biometric data. As an example, advanced “smart” functions and features similar to those provided on smartphones, smartwatches, optical head-mounted displays or helmet-mounted displays can be included therein. Example functions of computing devices may include, without being limited to, capturing images and/or video, displaying images and/or video, presenting audio signals, presenting text messages and/or emails, identifying voice commands from a user, browsing the web, etc. 
     In one exemplary embodiment of the present invention, there exists a communication earphone/headset system connected to a voice communication device (e.g. mobile telephone, radio, computer device) and/or audio content delivery device (e.g. portable media player, computer device). Said communication earphone/headset system comprises a sound isolating component for blocking the users ear meatus (e.g. using foam or an expandable balloon); an Ear Canal Receiver (ECR, i.e. loudspeaker) for receiving an audio signal and generating a sound field in a user ear-canal; at least one ambient sound microphone (ASM) for receiving an ambient sound signal and generating at least one ASM signal; and an optional Ear Canal Microphone (ECM) for receiving a narrowband ear-canal signal measured in the user&#39;s occluded ear-canal and generating an ECM signal. A signal processing system receives an Audio Content (AC) signal from the said communication device (e.g. mobile phone etc) or said audio content delivery device (e.g. music player); and further receives the at least one ASM signal and the optional ECM signal. Said signal processing system processing the narrowband ECM signal to generate a modified ECM signal with increased spectral bandwidth. 
     In a second embodiment, the signal processing for increasing spectral bandwidth receives a narrowband speech signal from a non-microphone source, such as a codec or Bluetooth transceiver. The output signal with the increased spectral bandwidth is directed to an Ear Canal Receiver of an earphone or a loudspeaker on another wearable device. 
       FIG.  1 E  illustrates an earpiece as part of a system  40  according to at least one exemplary embodiment, where the system includes an electronic housing unit  100 , a battery  102 , a memory (RAM/ROM, etc.)  104 , an ear canal microphone (ECM)  106 , an ear sealing device  108 , an ECM acoustic tube  110 , a ECR acoustic tube  112 , an ear canal receiver (ECR)  114 , a microprocessor  116 , a wire to second signal processing unit, other earpiece, media device, etc. ( 118 ), an ambient sound microphone (ASM)  120 , a user interface (buttons) and operation indicator lights  122 . Other portions of the system or environment can include an occluded ear canal  124  and ear drum  126 . 
     The reader is now directed to the description of  FIG.  1 E  for a detailed view and description of the components of the earpiece  100  (which may be coupled to the aforementioned devices and media device  50  of  FIG.  5    for example), components which may be referred to in one implementation for practicing the methods described herein. Notably, the aforementioned devices (headset  10 , eyeglasses  20 , mobile device  14 , wrist watch  16 , earpiece  100 ) can also implement the processing steps of methods herein for practicing the novel aspects of spectral enhancement of speech signals. 
       FIG.  1 E  is an illustration of a device that includes an earpiece device  100  that can be connected to the system  10 ,  20 , or  50  of  FIG.  1 A,  2 A , or  5 , respectively for example, for performing the inventive aspects herein disclosed. As will be explained ahead, the earpiece  100  contains numerous electronic components, many audio related, each with separate data lines conveying audio data. Briefly referring back to  FIG.  1 B , the system  20  can include a separate earpiece  100  for both the left and right ear. In such arrangement, there may be anywhere from 8 to 12 data lines, each containing audio, and other control information (e.g., power, ground, signaling, etc.) 
     As illustrated, the system  40  of  FIG.  1 E  comprises an electronic housing unit  100  and a sealing unit  108 . The earpiece depicts an electro-acoustical assembly for an in-the-ear acoustic assembly, as it would typically be placed in an ear canal  124  of a user. The earpiece can be an in the ear earpiece, behind the ear earpiece, receiver in the ear, partial-fit device, or any other suitable earpiece type. The earpiece can partially or fully occlude ear canal  124 , and is suitable for use with users having healthy or abnormal auditory functioning. 
     The earpiece includes an Ambient Sound Microphone (ASM)  120  to capture ambient sound, an Ear Canal Receiver (ECR)  114  to deliver audio to an ear canal  124 , and an Ear Canal Microphone (ECM)  106  to capture and assess a sound exposure level within the ear canal  124 . The earpiece can partially or fully occlude the ear canal  124  to provide various degrees of acoustic isolation. In at least one exemplary embodiment, assembly is designed to be inserted into the user&#39;s ear canal  124 , and to form an acoustic seal with the walls of the ear canal  124  at a location between the entrance to the ear canal  124  and the tympanic membrane (or ear drum). In general, such a seal is typically achieved by means of a soft and compliant housing of sealing unit  108 . 
     Sealing unit  108  is an acoustic barrier having a first side corresponding to ear canal  124  and a second side corresponding to the ambient environment. In at least one exemplary embodiment, sealing unit  108  includes an ear canal microphone tube  110  and an ear canal receiver tube  112 . Sealing unit  108  creates a closed cavity of approximately 5 cc between the first side of sealing unit  108  and the tympanic membrane in ear canal  124 . As a result of this sealing, the ECR (speaker)  114  is able to generate a full range bass response when reproducing sounds for the user. This seal also serves to significantly reduce the sound pressure level at the user&#39;s eardrum resulting from the sound field at the entrance to the ear canal  124 . This seal is also a basis for a sound isolating performance of the electro-acoustic assembly. 
     In at least one exemplary embodiment and in broader context, the second side of sealing unit  108  corresponds to the earpiece, electronic housing unit  100 , and ambient sound microphone  120  that is exposed to the ambient environment. Ambient sound microphone  120  receives ambient sound from the ambient environment around the user. 
     Electronic housing unit  100  houses system components such as a microprocessor  116 , memory  104 , battery  102 , ECM  106 , ASM  120 , ECR,  114 , and user interface  122 . Microprocessor ( 116 ) can be a logic circuit, a digital signal processor, controller, or the like for performing calculations and operations for the earpiece. Microprocessor  116  is operatively coupled to memory  104 , ECM  106 , ASM  120 , ECR  114 , and user interface  120 . A wire  118  provides an external connection to the earpiece. Battery  102  powers the circuits and transducers of the earpiece. Battery  102  can be a rechargeable or replaceable battery. 
     In at least one exemplary embodiment, electronic housing unit  100  is adjacent to sealing unit  108 . Openings in electronic housing unit  100  receive ECM tube  110  and ECR tube  112  to respectively couple to ECM  106  and ECR  114 . ECR tube  112  and ECM tube  110  acoustically couple signals to and from ear canal  124 . For example, ECR outputs an acoustic signal through ECR tube  112  and into ear canal  124  where it is received by the tympanic membrane of the user of the earpiece. Conversely, ECM  114  receives an acoustic signal present in ear canal  124  though ECM tube  110 . All transducers shown can receive or transmit audio signals to a processor  116  that undertakes audio signal processing and provides a transceiver for audio via the wired (wire  118 ) or a wireless communication path. 
       FIG.  2    illustrates an exemplary configuration of the spectral expansion method  200 . The method  200  for automatically expanding the spectral bandwidth of a speech signal can comprise the steps of: 
     Step 1. A first training step generating a “mapping” (or “prediction”) matrix  206  based on the analysis  203  of a reference wideband signal  201  and a reference narrowband signal  204 . The mapping matrix is a transformation matrix to predict high frequency energy from a low frequency energy envelope. In one embodiment a frequency transform  202  is performed on the reference wideband signal  201  and a frequency transform  205  into N Bands is performed on the low bandwidth reference signal  204 . In one exemplary configuration, the reference wideband and narrowband signals are made from a simultaneous recording of a phonetically balanced sentence made with an ambient microphone located in an earphone and an ear canal microphone located in an earphone of the same individual (i.e. to generate the wideband and narrowband reference signals, respectively). 
     Step 2. Generating an energy envelope analysis  209  of an input narrowband audio signal  207 . In one embodiment, the narrowband audio signal  207  is frequency transformed at  208 . 
     Step 3: Generating at  210  a resynthesized noise signal by processing a random noise signal  211  with the mapping matrix  206  of step 1 and the envelope analysis  209  of step 2. The resynthesis at  201  provides a wideband noise signal  212 . 
     Step 4: High-pass filtering at  213  the resynthesized noise signal  212  of step 3. 
     Step 5: Summing at  214  the high-pass filtered resynthesized noise signal with the original input narrowband audio signal  207  to provide a wideband signal  215 . 
       FIG.  3    is an exemplary method  300  for generating the mapping (or “prediction”) matrix  309 . There are at least two things that are of note about the method: One is that we&#39;re taking an intermediate approach between a very simple model (that the energy in 3.5-4 kHz gets extended to 8 kHz, say), and a very complex model (that attempts to classify the phoneme at every frame, and deploy a specific template for each case). We have a simple, mode-less model, but it has quite a few parameters, which we learn from training data. 
     In the model, there are sufficient input channels for an accurate prediction, but not so many that we need a huge amount of training data, or that we end up being unable to generalize. In one embodiment, a low bandwidth reference signal  301  and a high bandwidth reference signal  304  are provided as inputs that are both respectively frequency transformed into N bands at  302  and  305  respectively. 
     The second approach or aspect of note of the method is that we use the “dB domain” (at  303  and  306  respectively) to do the linear prediction (this is different from the LPC approach). 
     The logarithmic dB domain is used since it has the ability to provide a good fit even for the relatively low-level energies. If you just do least squares at  307  on the linear energy, it puts all its modeling power into the highest 5% of the bins, or something, and the lower energy levels, to which human listeners are quite sensitive, are not well modeled (NB “mapping” and “prediction” matrix are used interchangeably). In one embodiment, a high bandwidth mapping matrix  308  is performed after the least-squares fit at  307  before providing the mapping matrix  309 . 
       FIG.  4    shows an exemplary configuration of the spectral expansion system for increasing the spectral content of two signals: 
     1. A first outgoing signal  401  where the narrowband input signal is from an Ear Canal Microphone signal in an earphone (the “near end” signal), and the output signal from the spectral expansion system  402  is directed to a “far-end” loudspeaker  403  via a voice telecommunications system. 
     2. An incoming signal from the same spectral expansion system  402  or a second spectral expansion system  402   a  processes a received voice signal from a far-end system, e.g. a received voice system from a cell-phone. Here, the output of the spectral expansion system  402  or  402   a  is directed to the loudspeaker  405  in an earphone of the near-end party. 
       FIG.  5    depicts various components of a multimedia device  50  suitable for use for use with, and/or practicing the aspects of the inventive elements disclosed herein, for instance the methods of  FIG.  2  or  3   , though it is not limited to only those methods or components shown. As illustrated, the device  50  comprises a wired and/or wireless transceiver  52 , a user interface (UI) display  54 , a memory  56 , a location unit  58 , and a processor  60  for managing operations thereof. The media device  50  can be any intelligent processing platform with Digital signal processing capabilities, application processor, data storage, display, input modality or sensor  64  like touch-screen or keypad, microphones, and speaker  66 , as well as Bluetooth, and connection to the internet via WAN, Wi-Fi, Ethernet or USB. This embodies custom hardware devices, Smartphone, cell phone, mobile device, iPad and iPod like devices, a laptop, a notebook, a tablet, or any other type of portable and mobile communication device. Other devices or systems such as a desktop, automobile electronic dash board, computational monitor, or communications control equipment is also herein contemplated for implementing the methods herein described. A power supply  62  provides energy for electronic components. 
     In one embodiment where the media device  50  operates in a landline environment, the transceiver  52  can utilize common wire-line access technology to support POTS or VoIP services. In a wireless communications setting, the transceiver  52  can utilize common technologies to support singly or in combination any number of wireless access technologies including without limitation Bluetooth™ Wireless Fidelity (WiFi), Worldwide Interoperability for Microwave Access (WiMAX), Ultra Wide Band (UWB), software defined radio (SDR), and cellular access technologies such as CDMA-1X, W-CDMA/HSDPA, GSM/GPRS, EDGE, TDMA/EDGE, and EVDO. SDR can be utilized for accessing a public or private communication spectrum according to any number of communication protocols that can be dynamically downloaded over-the-air to the communication device. It should be noted also that next generation wireless access technologies can be applied to the present disclosure. 
     The power supply  62  can utilize common power management technologies such as power from USB, replaceable batteries, supply regulation technologies, and charging system technologies for supplying energy to the components of the communication device and to facilitate portable applications. In stationary applications, the power supply  62  can be modified so as to extract energy from a common wall outlet and thereby supply DC power to the components of the communication device  50 . 
     The location unit  58  can utilize common technology such as a GPS (Global Positioning System) receiver that can intercept satellite signals and there from determine a location fix of the portable device  50 . 
     The controller processor  60  can utilize computing technologies such as a microprocessor and/or digital signal processor (DSP) with associated storage memory such a Flash, ROM, RAM, SRAM, DRAM or other like technologies for controlling operations of the aforementioned components of the communication device. 
     It should be noted that the methods  200  in  FIG.  2  or  3    are not limited to practice only by the earpiece device shown in  FIG.  1 E . Examples of electronic devices that incorporate multiple microphones for voice communications and audio recording or analysis, include, but not limited to:
         a. Smart watches.   b. Smart “eye wear” glasses.   c. Remote control units for home entertainment systems.   d. Mobile Phones.   e. Hearing Aids.   f. Steering wheels.       

     Such embodiments of the inventive subject matter may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. 
     Where applicable, the present embodiments of the invention can be realized in hardware, software or a combination of hardware and software. Any kind of computer system or other apparatus adapted for carrying out the methods described herein are suitable. A typical combination of hardware and software can be a mobile communications device or portable device with a computer program that, when being loaded and executed, can control the mobile communications device such that it carries out the methods described herein. Portions of the present method and system may also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein and which when loaded in a computer system, is able to carry out these methods. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions of the relevant exemplary embodiments. Thus, the description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the exemplary embodiments of the present invention. Such variations are not to be regarded as a departure from the spirit and scope of the present invention. 
     For example, the spectral enhancement algorithms described herein can be integrated in one or more components of devices or systems described in the following U.S. Patent Applications, all of which are incorporated by reference in their entirety: U.S. patent application Ser. No. 11/774,965 entitled Personal Audio Assistant docket no. PRS-110-US, filed Jul. 9, 2007 claiming priority to provisional application 60/806,769 filed on Jul. 8, 2006; U.S. patent application Ser. No. 11/942,370 filed 2007 Nov. 19 entitled Method and Device for Personalized Hearing docket no. PRS-117-US; U.S. patent application Ser. No. 12/102,555 filed 2008 Jul. 8 entitled Method and Device for Voice Operated Control docket no. PRS-125-US; U.S. patent application Ser. No. 14/036,198 filed Sep. 25, 2013 entitled Personalized Voice Control docket no. PRS-127US; U.S. patent application Ser. No. 12/165,022 filed Jan. 8, 2009 entitled Method and device for background mitigation docket no. PRS-136US; U.S. patent application Ser. No. 12/555,570 filed 2013 Jun. 13 entitled Method and system for sound monitoring over a network, docket no. PRS-161US; and U.S. patent application Ser. No. 12/560,074 filed Sep. 15,2009 entitled Sound Library and Method, docket no. PRS-162US. 
     This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description. 
     These are but a few examples of embodiments and modifications that can be applied to the present disclosure without departing from the scope of the claims stated below. Accordingly, the reader is directed to the claims section for a fuller understanding of the breadth and scope of the present disclosure.