Patent Publication Number: US-8538492-B2

Title: System and method for localized noise cancellation

Description:
BACKGROUND 
     In recent years, more and more individuals and employees work in close proximity. The close quarters of many office environments result from increasing expenses, lack of available office space, expanding business, and desired proximity of employees for purposes of efficiency. Cubicle- and open-office type settings are particularly prevalent because of the perceived efficient usage of space that allows a large number of people to work in close proximity to one another. 
     Although cubicles may be used to efficiently exploit available office space, cubicles lack privacy, allowing conversations, speech, and other information, to be easily overheard by others within the office. Hearing others&#39; conversations or noise generated by others or their office equipment may be distracting or prohibitive while working, on the phone, or carrying on one&#39;s own conversation. Some users feel uncomfortable carrying on a conversation in public because they prefer privacy for sharing personal, business, or other information. As a result, working in a similar office environment may be frustrating and inconvenient. 
     SUMMARY 
     One embodiment includes a system and method for localized noise cancellation and is received from an environment in close proximity to a primary area. The audio signal is processed to generate an inverse signal of the audio signal. The inverse signal is broadcast within the primary area to destructively interfere with the audio signal. The inverse signal is configured to prevent the audio signal from being broadcast through a telephone conversation ongoing in the primary area. 
     Another embodiment includes a noise cancellation system. The noise cancellation system may include one or more microphones configured to receive an audio signal from areas in near proximity to a primary area. The noise cancellation system may also include a noise cancellation device including a signal generator in communication with the one or microphones configured to process the voice communication to determine a voice signal and the inverse of the voice signal. The noise cancellation system may also include one or more speakers in communication with the noise cancellation device configured to broadcast the inverse signal within the primary area as the audio signal is received for reducing the audio signal discernible by one or more users communicating using a telephone within the primary area. 
     Yet another embodiment includes a method for providing noise cancellation for a telephone conversation. An original signal entering the primary area of an open environment may be received and digitally approximated. An inverse signal to the original signal may be generated and the inverse signal is amplified. The inverse signal may broadcast to interfere with the original signal. The inverse signal may operate to cause the original signal to be less discernible by parties involved in a telephone conversation in the primary area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the present invention are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein and wherein: 
         FIG. 1  is a pictorial representation of a conversation environment in accordance with an illustrative embodiment; 
         FIG. 2  is a pictorial representation of a noise cancellation environment in accordance with an illustrative embodiment; 
         FIG. 3  illustrates noise cancellation signals in accordance with an illustrative embodiment; 
         FIG. 4  is a block diagram of a noise cancellation system in accordance with an illustrative embodiment; 
         FIG. 5  is a flowchart of a process for noise cancellation in accordance with an illustrative embodiment; and 
         FIG. 6  is a flowchart of a process for generating an inverse signal in accordance with an illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Illustrative embodiments provide a system and method for localized noise cancellation. Speech and noise entering a primary area in the form of an audio signal may be processed. A response signal may be generated to interfere with the audio signal. In one embodiment, the response signal is an inverse signal or digital approximation of the audio signal that is 180 degrees out of phase. The audio signal and the inverse signal may destructively interfere to provide individuals within the primary area increased privacy and a quieter work environment to more efficiently perform various work tasks. In particular, the inverse signal may be used to ensure that voice communications using a telephonic device, such as a wireless telephone, standard telephone, or Voice over Internet Protocol (VoIP) telephone, may occur without excessive background noise. 
       FIG. 1  is a pictorial representation of a conversation environment in accordance with an illustrative embodiment. The conversation environment  100  is any environment in which various sounds, noises, and speech are present and conversations may occur between any number of individuals. The conversation environment  100  may include a primary area  102 , a telephone  103 , a cubicle  104 , a cubicle  106 , a secondary area  108 , individuals  110 ,  112 ,  114 ,  116 ,  118 ,  120 , and  122 , a noise cancellation device  124  and microphones  126 ,  128 , and  130 . As shown in  FIG. 1 , the conversation environment  100  may be a building, office space, or home. However, the conversation environment  100  may be any location, such as a restaurant, building, or other environment suitable for users to carry on a conversation. Illustrative embodiments may be particularly useful in an open office environment. 
     The primary area  102  is an area in which a noise or noise cancellation system may be utilized to enhance effective verbal or telephonic communications involving individuals  110  and  112 . As shown, the primary area  102  may be surrounded or abutted by areas in which noises, sounds, speech, and conversations may be generated. For example, the individuals  114 ,  116 ,  118 ,  120 , and  122  may be carrying on conversations amongst themselves, on the telephone, or may otherwise be generating sound that may constitute noise and/or speech. The noise and speech in the form of audio signals may propagate through the air from the cubicles  104  and  106 , and the secondary area  108 , into the primary area  102 . 
     In one example, the speech and noise from each of these areas may interfere with the communications between the individuals  110  and  112 . As a result, the individuals  110  and  112  may be unable to effectively concentrate, convey words and messages, or otherwise communicate with one another. Effective communication between the individuals  110  and  112  may be necessary in order to convey thoughts and ideas, perform business transactions, and maintain effective social communications. 
     In particular, the individuals  110  and  112  may be involved in a phone conference using the telephone  103  and they, as well as, the party(ies) with whom the individuals  110  and  112  are communicating may be unable to effectively communicate because of the incoming audio signals from the conversation environment. In one embodiment, the telephone  103  may be a cellular telephone. However, the telephone  103  may be any communications device suitable for carrying on a verbal conversation, including, but not limited to, a plain old telephone service (POTS) telephone, VoIP phone, base station and cordless handset, and conference phone. 
     In one embodiment, the individuals  110  and  112  may activate a noise cancellation device  124  for the primary area  102 . For example, the individual  110  may turn on a power switch of the noise cancellation device  124  which may activate the microphones  126 ,  128 , and  130 . In another embodiment, the noise cancellation system may function at all times to ensure effective communications of one or more individuals within the primary area  102 . The noise cancellation device  124  may also be automatically activated based on time of day, usage of the telephone  103 , or motion sensors. 
     As shown, the primary area  102  is the only portion of the conversation environment  100  that includes a noise cancellation system. However, any number of noise cancellation systems or a single integrated noise cancellation system may be implemented to ensure effective communications within the primary area  102 , the cubicles  104  and  106 , and the secondary area  108  based on the needs of the individuals within the conversation environment  100 . 
     The noise cancellation system, and particularly the noise cancellation device  124 , is further described in  FIG. 2  and  FIG. 4 . The microphones  126 ,  128 , and  130  are auditory input devices configured to receive sound, speech, and other noises propagating into the primary area  102  from the surrounding cubicles  104 ,  106 , and the secondary area  108 , and from other areas within the conversation environment  100 . As shown, the primary area  102  may be a cubicle or office in which the individual  110  or individuals  110  and  112  work, live, or otherwise caryon business. 
     The microphones  126 ,  128 , and  130  may be strategically located in order to receive the loudest or interfering speech, noise, or sounds from the surrounding areas. The microphones  126 ,  128 , and  130  may be wired to the noise cancellation device  124 . In another embodiment, the microphones  126 ,  128 , and  130  may wirelessly communicate with the noise cancellation device  124 . For example, the microphones  126 ,  128  and  130  may use a WiFi, Bluetooth, or WiMAX connection in order to send sounds, noises, and speech or the electronic waveforms, received from the cubicles  104  and  106  and the secondary area  108 , to the noise cancellation device  124 . 
     The noise cancellation system may be hard wired or portable. For example, the noise cancellation system, including the noise cancellation device  124  and microphones  126 ,  128 , and  130 , may be installed at the time the cubicles are assembled or at the time the office or conversation environment  100  is constructed. In another embodiment, the noise cancellation system may be a portable system suitable to be temporarily installed, or uninstalled as needed, in order to enhance communications within the primary area  102 . Correspondingly, the noise cancellation system may be battery powered or may be hard wired into a power infrastructure of the conversation environment  100 , a building, or another available power source. 
     The microphones  126 ,  128  and  130  may be directionally mounted in order to receive sounds, signals, and noises that are most likely to interfere with voice and telephone communications within the primary area  102 . As shown, the microphones  126 ,  128  and  130  are directionally focused on the cubicle  104 , the cubicle  106 , and the secondary area  108  in from which sounds, noises, and conversations are most likely to enter the primary area. 
     The noise cancellation device  124  receives the audio input or audio signals from each of the microphones  126 ,  128 , and  130  and processes the incoming signals individually or as a group in order to generate an inverse signal. The inverse signal may be a digital approximation of the audio signals received from each of the microphones  126 ,  128  and  130 , with the exception that the inverse signal is out of phase with the combined signals received from the cubicles  104  and  106  and the secondary area  108 . In one embodiment, the inverse signal is 180 degrees out of phase with the combined signals received so that when added through propagation the signals destructively interfere. 
     The noise cancellation device  124  may process the audio signals from the surrounding areas to generate the inverse signal based on the amplitude, frequency, phase, and other characteristics of the analog audio signals. The phase of the inverse signal may be tuned based on the feedback and analysis that may be performed by the noise cancellation device  124  to ensure destructive interference is occurring. The noise cancellation device  124  may then use an integrated multi-direction speaker to broadcast the inverse signal or inverse signals in the primary area  102  for the benefit of the individuals  110  and  112 . As a result, the conversation and/or telephone communication involving the individuals  110  and  112  may be readily distinguishable and outside noise coming into the primary area  102  from the cubicles  104 , and  106  and the secondary area  108  may be substantially decreased or cancelled out. 
     The noise cancellation device  124  may dynamically adjust the inverse signal that is broadcast based on changes in frequency, volume, other voice and noise characteristics of the audio signals received by the microphones  126 ,  128 , and  130 . The noise cancellation device  124  may be used to ensure that a party on the other end of a voice conversation with the individuals  110  and  112  through the telephone  103  is able to hear what the individuals  110  and  112  are communicating, regardless of the happenings in the conversation environment  100 . In part, the cancelling waveform may be determined by the distance and configuration of the one or more microphones and the one or more speakers broadcasting the inverse signal. The inverse signal may be broadcast at a lower amplitude because the individuals  110  and  112  are farther away from the sounds coming from the cubicles  104  and  106  and the secondary area and the incoming sounds be further attenuated as it propagates and is heard by the individuals  110  and  112 . 
     Additionally, the noise cancellation device  124  may compensate for humidity, air temperature, air pressure, viscosity, and other propagation and interference factors. In addition, the noise cancellation device  124  may compensate for glass walls, furniture, and other obstacles and mediums that may diffract sound waves in the conversation environment  100 . As sound propagates through the air throughout a distance, the decibel levels decrease because of the inherent nature by which sound waves propagate through air molecules. The noise cancellation device  124  may compensate for distances between the microphones  126 ,  128 , and  130 , the noise cancellation device  124 , and primary area  102 . As mentioned, audio signals and sound waves lose energy as they propagate. As a result, the noise cancellation device  124  and corresponding speakers may broadcast the inverse signal based on the distance between the microphones  126 ,  128 , and  130 , speaker, and the other configuration of the primary area  102 . 
     The noise cancellation device  124  may be connected to one or more speakers that may broadcast the inverse signal generated by the noise cancellation device. In one example, the microphones  126 ,  128 , and  130  may also include a speaker for directionally broadcasting the inverse signal received from each of the cubicles  104 ,  106 , and secondary area  108 , respectively. The inverse signal as referred to herein may include any number of inverse signals generated and broadcast for the benefit of the primary area  102 . The inverse signal(s) may be configured to individually or collectively destructively interfere with the audio signals that are propagated from the cubicles  104  and  106  and the secondary area  108  toward the primary area  102 . As a result of the destructive interference, the individuals  110  and  112  may be better able to carry on a telephone conversation without extraneous audio signals. 
     In another embodiment, the audio signals generated within the primary area may be monitored in order to ensure the privacy of the individuals  110  and  112 . For example, the microphones  126 ,  128 , and  130  may receive signals from within the primary area  102 . The microphones  126 ,  128 , and  130  may also include speakers. The audio signals from within the primary area  102  may be processed from each of the microphones  126 ,  128 , and  130  to generate multiple response signals that are then broadcast by the microphones  126 ,  128 , and  130  to make the voice signals emanating from within the primary area  102  to the cubicles  104 ,  106 , and secondary area  108  less intelligible, the result being that the individuals  114 ,  116 ,  118 ,  120 , and  122  may be unable to distinguish speech generated within the primary area  102 . The response signals broadcast may make the speech, words, and noises emanating from the primary area  102  unintelligible by distorting or otherwise cancelling the original audio signals. 
     In one embodiment, the response signal may be an inverse signal or a disruption signal. The response signal may be a digital approximation of the voice communications occurring in the primary area  102  with the only difference being that the response signal is out of phase with the voice communications signal. For example, the response signal may be an inverse signal 180 degrees out of phase with the voice communication signal. 
     The response signal may be approximated and generated by the noise cancellation device  124  to destructively interfere with voice communications, such as a phone conversation through the telephone  103 . The response signal may be emitted as controlled by the noise cancellation device  124  to ensure that the voice communications spoken by the individuals  110  and  112  are substantially decreased or cancelled as they leave the primary area  102 . The response signal may function as a cancellation signal intended to be of equal amplitude and opposite phase of the voice communications within the primary area  102 . 
     In another embodiment, the response signal may be unable to completely destructively interfere with the voice communications occurring in the primary area  102 . However, the response signal may make the words and meaning of the conversation unintelligible by distorting or otherwise modifying the original voice communications signal once combined. Once the voice communications signal  114  and distortion signal combine, the originally spoken words and sounds become distorted, muddled, and otherwise unintelligible. In one example, the distortion signal may be the verbal phone conversation of the individuals  110  and  112 , played at a different pitch and with a slight time delay for making any signals overheard in the cubicles  104  and  106  and secondary area  108  seem like overlapping conversations. Pitch refers to the perceived fundamental frequency of a sound. In another embodiment, additional sounds, pre-recorded words, conversations, or noises, random tones, and frequent pitch changes may be integrated or played as part of the distortion signal. In another example, the response signal  116  may be an inverse signal generated at a lower power level with the purpose of convoluting or dampening the original communications signal  114 . 
     The noise cancellation device  124  may be configured to destructively interfere with the sounds, voice signals, and noises generated outside or within the primary area based on a user selection or preference. In one embodiment, the noise cancellation system, and particularly the noise cancellation device  124 , may broadcast inverse signals within the primary area  102  to destructively interfere with audio signals entering the primary area  102  and concurrently generate inverse signals that are broadcast to cubicle  104 , cubicle  106 , and secondary area  108  to destructively interfere with the voice signals that are generated by the individuals  110  and  112  from within the primary area  102 . As a result, the individuals  110 ,  112 ,  114 ,  116 ,  118 ,  120 , and  122  may all more effectively communicate within their respective areas, knowing that the noise cancellation system may provide them with enhanced privacy, security, and a more personal environment fostering better communications. 
     In another embodiment, the noise cancellation device  124  may be an integrated portion of the telephone  103 . For example, the microphone, speaker, and noise cancellation features may be part of the telephone  103 . The speaker for receiving incoming signals may be part of a cordless handset and the signal generator, noise cancellation functionality, and speaker may be part of the cordless base station. The telephone  103  may also be a cellular telephone, conference phone, or other telephone device that may perform noise cancellation or portions of the localized noised cancellation features herein described. 
       FIG. 2  is a pictorial representation of a noise cancellation environment in accordance with an illustrative embodiment.  FIG. 2  includes a noise cancellation environment  200  which is a particular implementation of the primary area  102  of  FIG. 1 . The noise cancellation environment  200  may include elements of a noise cancellation system, including a noise cancellation device  202 , a speaker  204 , microphones  206 ,  208 , and  210  and telephone  211 . The noise cancellation environment  200  may further include an inverse signal  212 , signals  214 ,  216 , and  218 , voice communication signal  220 , and users  222  and  224 . 
     Signals  214 ,  216 , and  218  represent the audio signals or audio waves received by the microphones  206 ,  208 , and  210  from the surrounding areas. The microphones  206 ,  208 , and  210  may collectively communicate with the noise cancellation device  202  through a wired or wireless connection. In another embodiment, the speaker  204  and microphones  206 ,  208 , and  210  may individually communicate with the noise cancellation device  202  through a wired or wireless connection. 
     The noise cancellation device  202  may similarly process the signals  214 ,  216 , and  218  individually or as a group. In one embodiment, the signals  214 ,  216 , and  218  are individually processed by the noise cancellation device  202  in order to generate individual inverse wave forms as received from each of the microphones  206 ,  208 , and  210 . The generation of the inverse signal is further described in  FIG. 6 . 
     The speaker  204  may be an audio output device that is configured to output the inverse signal  212 . The speaker  204  may be integrated with the cancellation device  202  or may be networked to the noise cancellation device  202  through a wired or wireless connection. In one embodiment, the noise cancellation environment  200  includes a single speaker  204 . In other embodiments, the noise cancellation environment  200  may include a number of speakers strategically located to broadcast the inverse signal  212  for the benefit of the users  222  and  224 . 
     As previously described, the microphones  206 ,  208 , and  210  may incorporate the features of the speaker  204  in order to broadcast the inverse signal  212  that destructively interferes with each of the signals  214 ,  216 , and  218 . In another embodiment, the speaker  204  may output the inverse signal  212  in multiple directions. For example, the speaker  204  may be optimally positioned or directionally focused to broadcast the inverse signal  212  to interfere with the signals  214 ,  216 , and  218  in order to maximize destructive interference or distortion of the signals  214 ,  216 , and  218 . 
     The noise cancellation device  202 , and its respective noise cancellation elements, ensure that the voice communication signal  220  exchanged between the users  222  and  224  is not disrupted, overpowered, or convoluted by the signals  214 ,  216 , and  218 . In one embodiment, the voice communication signal  220  may be part of a conversation between the individuals  222  and  224 , as well as one or more individuals communicating through the telephone  211 . Many individuals have experienced frustration from trying to concentrate on the speech of another individual during a phone conversation when multiple conversations, background noises, other sounds are interfering with the user&#39;s hearing. For example, it may be difficult to concentrate on a single conversation when multiple conversations, in the form of signals  214 ,  216 , and  218 , are propagating into the voice cancellation environment  200 . The inverse signal  212  destructively interferes with the signals  214 ,  216 , and  218  to enhance communications between the users  222  and  224  and verbal conversations through the telephone  211 . 
     For example, the users  222  and  224  may be carrying on a phone conversation or conference call with another individual, and by activating the noise cancellation device  202 , the signals  214 ,  216 , and  218  may not be communicated through the communications link to the other party. As a result, even though the users  222  and  224  may be surrounded by any number of individuals, offices, cubicles, or sounds, the voice communication signal  220  may be effectively communicated without substantial interference. 
     In one embodiment, the telephone  211  is connected to the noise cancellation device  208 . A dialed or received call activates the noise cancellation device  208 . Similarly the noise cancellation device may use adaptive filtering to ensure that the inverse signal  212  does not feed back into the telephone. 
       FIG. 3  illustrates noise cancellation signals in accordance with an illustrative embodiment.  FIG. 3  includes a number of signals that may be present in the conversation environment  100  of  FIG. 1 . The various signals are electronically represented by a wave form as a visual aid to further describe the illustrative embodiments.  FIG. 3  includes a secondary signal  302 , a primary signal  304 , an inverse signal  306 , and a combined signal  308 . The processing of the signals of  FIG. 3  are further described in  FIG. 6 . 
     The secondary signal  302  may be a particular implementation of signals  214 ,  216  and  218  received from the microphones  206 ,  208 , and  210 , all of  FIG. 2 . In other words, the secondary signal  302  may be the audio signal(s) most likely to interfere with telephone and voice communications within a primary area. The secondary signal  302  may represent the speech, noises, and sounds from individuals, equipment or machines, or background noise that propagates into the primary area. As previously mentioned, the secondary signal may be a single signal or a combination of signals. The secondary signal  302  may vary in frequency and amplitude based on the loudness and types of sounds received by one or more microphones. 
     The primary signal  304  is a particular implementation of the voice communication signal  220  of  FIG. 2 . In one embodiment, the primary signal  304  may be the signal that multiple users desire to effectively communicate with each other in person or through a communications-enabled device. 
     The inverse signal  306  may be the signal that is processed and generated by a noise cancellation device in order to destructively interfere with the secondary signal  302 . In one example, the inverse signal is an approximation of the secondary signal that is 180 degrees out of phase with the secondary signal  302 . The inverse signal  306  may be an approximation based on the limitations and processing abilities of the noise cancellation device and signal processing elements. In another example, the inverse signal  306  may be a distortion signal as previously described 
     The combined signal  308  may be the combination of the secondary signal  302 , the primary signal  304 , and the inverse signal  306 . As shown by the combined signal  308 , the secondary signal  302 , and the inverse signal  306  have destructively interfered to effectively cancel each other out. The combined signal  308  is distinguished by the similarities to the primary signal  304 . As a result, the combined signal, as processed by the human auditory system and brain, nearly approximates the primary signal as originally spoken by one or more users. 
     The extraneous sounds, noises, and speech in the form of the secondary signal  302  may be minimized or cancelled by the inverse signal  306  so that the human auditory system is able to distinguish only the speech, sounds, and noises conveyed by the primary signal  304  from the combined signal  308 . 
       FIG. 4  is a block diagram of a noise cancellation system in accordance with an illustrative embodiment. The noise cancellation system  400  may be a particular implementation of the noise cancellation device  401  and interconnected elements of  FIG. 2 . The noise cancellation device  401  may include various elements including a digital signal processor  402 , a memory  404 , feedback logic  405 , an amplifier  406 , a speaker  408 , and a microphone network  410 . The speaker  408  and the microphone network  410  may be integrated with the noise cancellation device  401  or may be externally connected as shown in the embodiment of  FIG. 4 . 
     The noise cancellation device  401  may be a combination of hardware and software elements which may be implemented using various structures and implementations. The example shown in  FIG. 4  is given for illustration purposes only, and not as a limitation of required elements. The noise cancellation device  401  may be enabled to provide localized noise and voice cancellation in order to enhance communications and privacy. 
     The digital signal processor  402  may be a signal processing device, noise cancellation logic, chipset, a signal generator, or an amplifier. The digital signal processor  402  may also be any processing device suitable for processing speech, sound, noise, and communications signals. In another embodiment, the digital signal processor may include other hardware and/or software implementing conversation privacy logic configured to generate the inverse signal broadcast from the speaker  408  of the noise cancellation device  400  or an externally-linked speaker. 
     In particular, the digital signal processor  402  may include various pre-amplifiers, power amplifiers, digital-to-analog converters, and audio CODECs to dynamically generate a response signal to distort or destructively interfere with the specified voice conversation. The digital signal processor  402  may alternatively be a digital logic or a noise cancellation software program executed by a standard processor to analyze the incoming voice communications in order to generate the response signal. In particular, the digital signal processor  402  may receive audio input or signals from the microphone network. 
     The microphone network  410  may be one or more audio input devices configured to receive the audio input, voice communications, and noises from other areas or from an environment surrounding users of the noise cancellation device  401 . The microphone network  410  electronically communicates the voice communication signal to the digital signal processor  402 . The digital signal processor  402  analyzes the voice communications signal in order to generate the inverse signal, such as inverse signal  306  of  FIG. 3 . 
     The noise cancellation device  401  may include the feedback logic  405 , circuitry, or software suitable for ensuring that the inverse signal broadcast from the speaker  408  does not feed back into an interconnected telephone or the noise cancellation device  401  through the microphone network  410 . As a result, the user is able to clearly carry on a conversation even with substantial noises and sounds from the user&#39;s surrounding environment. The feedback logic  512  may include an adaptive or dynamic filter for filtering the inverse or response signal that feeds back through the microphone network  410  when broadcast through the speaker  408 . 
     The amplifier  406  may be used to amplify the inverse signal for output by the speaker  408 . Since each person naturally speaks at a different volume level, the amplifier  406  amplifies the inverse signal as needed to destructively interfere with the original voice communication signal. In one embodiment, a user may be able to set a privacy level for the noise cancellation device  401 . In some instances, the decision to select a specified privacy level may be based on the power output or signal amplitude required for the inverse signal broadcast from the speaker to destructively interfere with the original signals detected by the microphone network  410 . In the case of a batterypowered noise cancellation device, to generate an inverse signal that is most likely to render the voice communications completely unintelligible may require substantial power through the speaker  408  which may quickly drain a battery of the noise cancellation device  401 . As a result, the user may select a privacy level based on the required level of privacy and communications effectiveness balanced against the current battery or power availability. 
     The memory  404  may be a static or dynamic storage medium, such as static random access memory, flash memory, or dynamic random access memory. However, the memory may be a hard disk read-only memory, or other suitable form or combination of volatile or nonvolatile memory. The memory  404  may store user preferences, data, information, applications, and instructions for execution by the digital signal processor  402  to implement the noise cancellation functions of the noise cancellation device  401 . The user may establish noise cancellation preferences for dialed or received calls for various contacts, area codes, or phone numbers. For example, one or more phone numbers associated with the user&#39;s supervisor may be assigned the highest privacy level for ensuring that the conversation between the parties is as private as possible. As a result, the noise cancellation device  401  may be automatically activated and broadcast an inverse signal at full power when the user&#39;s supervisor is on the telephone. 
     The noise cancellation device  401  may further include a user interface and display which may include buttons, knobs, a touch screen, and other interactive elements to allow the user to enter and receive information. For example, the user may use an interface to set user preferences during times when the noise cancellation device  401  is automatically activated. The user preferences may also include power settings, microphone and speaker configuration, activation controls, and other features. 
     The noise cancellation device  401  may also automatically determine configuration information, including distances between the speaker  408 , microphone network  410 , and noise cancellation device  401 . The configuration is important because, depending on how the elements connected to the noise cancellation device  401  are configured, the amplifier  406  may need to increase or decrease the signal strength of the inverse signal to effectively destructively interfere with audio signals entering a primary area. In one embodiment, the noise cancellation device  401  may use wireless communication to effectively determine the distance from the speaker  408 , microphone network  410 , and a central point of the primary area. In another embodiment, a user may be required to manually enter information about the configuration of the noise cancellation system, including distance and direction, of the elements in  FIG. 4 . 
     The noise cancellation device  401  may be integrated with a personal computer or other computing device or audio system to perform the noise cancellation features herein described. For example, the noise cancellation device  401  may be an integrated part of a speaker telephone. The noise cancellation device  401  may also be a software program within a personal computer that controls noise cancellation for one or more designated areas. By activating the noise cancellation application, the user may ensure privacy and effective communications within an area. 
     In another embodiment, the noise cancellation device  401  may encompass a number of noise cancellation devices that are integrated into a single system. The noise cancellation device  401  may be a server that operates multiple other noise cancellation devices or noise cancellation clients including a VoIP telephone. For example, each area within an environment may include a noise cancellation device that is networked to the noise cancellation system. Each microphone network and speaker network may input information to the central noise cancellation system using a matrix, graph, signal chart, algorithm, or programs to effectively measure the audio signals received inside and outside of the area and distances and broadcast the inverse signal at power levels required to effectively limit the sounds entering the area through destructive interference. The noise cancellation system may use various feedback systems to ensure that the inverse signals broadcast from the multiple microphones do not feed back into one or more of the speaker networks. In one embodiment, the user may activate the noise cancellation device  401  by speaking a key word, pressing a button, or using a remote or wireless device. 
       FIG. 5  is a flowchart of a noise cancellation process in accordance with an illustrative embodiment. The process of  FIG. 5  may be implemented by a noise cancellation system. In particular, a noise cancellation device may implement the features, functions, and steps described by  FIG. 5 . 
     The process may begin by receiving user input to enable localized noise cancellation (step  502 ). The user input may be a user selection or activation of the noise cancellation device. For example, the user may select a switch or use a computing device in communication with the noise cancellation device to activate the localized voice cancellation. In one example, the user may select an icon on the user&#39;s desktop to enable localized voice cancellation. 
     Next, the noise cancellation device receives outside audio input from one or more microphones (step  504 ). The audio input may be received through a wired or a wireless connection. The audio input may include separate inputs from each microphone, or a single, combined audio input from a network of microphones. 
     The noise cancellation device processes the audio input to generate an inverse signal (step  506 ). The inverse signal may be an approximation of the audio input, in particular, the inverse signal may be 180 degrees out of phase with the audio input in order to ensure destructive interference as the audio input and inverse signal propagate through the air. 
     Next, the noise cancellation device broadcasts the inverse signal within a specified area (step  508 ). The signal may be broadcast in step  508  by electronically communicating the inverse signal with one or more speakers, which may convert the inverse signal into an audio signal in order to destructively interfere with the audio input as received in step  504 . The specified area may be the primary area in which one or more users desire to communicate without outside interference or other objectionable noises. 
       FIG. 6  is a flowchart of a process for generating an inverse signal in accordance with an illustrative embodiment. The process of  FIG. 6  may be implemented by a signal generator, digital signal processor, digital logic, amplifier, analog computing device, or signal processing application of a noise cancellation system or device. Alternatively, the process of  FIG. 7  may be wholly or partly performed by a stand-alone speaker integrating the features of a noise cancellation system in communication with the wireless device. 
     The determination to perform the process of  FIG. 6  may be performed based on user input. In one embodiment, the localized noise cancellation system may be constantly activated, activated during work hours, or motion activated. For example, once a call is made or received, or a visitor, guest, or associate, comes into the primary area, the noise cancellation system may be manually or automatically activated. 
     The process may begin by receiving the original analog signal (step  602 ). The original analog signal may be the speech, noise, and sounds entering a primary area from surrounding areas. The original analog signal may be the signal the user would like to prevent himself/herself and other parties within the primary area or communicating over the phone in the primary area from overhearing. The original analog signal may be a single signal or multiple signals from a microphone network. Likewise, each of the one or more received original analog signals may be processed as described by  FIG. 6  individually or separately. 
     The signal generator generates a digital approximation of the original analog signal (step  604 ). The signal generator may use any number of pre-amplifiers, buffers, or analog-to-digital converters to generate the digital approximation. Next, the signal generator generates an inverse signal of the digital approximation (step  606 ). The inverse signal may be the anti-original signal. The original analog signal or noises coming into the primary area consists of a spectrum of frequencies and different amplitudes. In order to effectively cancel out each waveform, the signal generator may separately filter each frequency, determine its frequency, and create the same frequency and amplitude at 180 degrees out of phase. 
     Next, the signal generator amplifies the inverse signal based on user preferences (step  608 ). The user preferences may specify the power or amplitude level of the inverse signal. For example, the user may have selected to attempt complete destructive interference with the original analog signal or just dampening of the original signal. The signal may also be generated in step  608  based on available battery power if the noise cancellation device is battery operated. During step  608 , the signal generator may also convert the inverse signal to an analog equivalent that may be broadcast through the available speaker or communicating device. 
     Next, the signal generator coordinates broadcasting of the inverse signal (step  610 ). The broadcasting may be performed by one or more speakers in communication with the noise cancellation device, an integrated speaker, or other linked device. Because the original analog signal received in step  602  may include so many frequencies and fractions of frequencies, the signal generator may selectively approximate a narrow band of frequencies of the original analog signal for generating the inverse signal. 
     The previous detailed description is of a small number of embodiments for implementing the invention and is not intended to be limiting in scope. The following claims set forth a number of the embodiments of the invention disclosed with greater particularity.