Abstract:
A system adjusts audio levels so as to maintain a constant perceived audio level at a user&#39;s location. The system includes a sensor ( 110 ) and an audio device ( 120 ). The sensor ( 110 ) receives a first audio signal, receives at least one data packet ( 1000 ) comprising a second audio signal, determines whether a difference between an average volume level of the first audio signal and the second audio signal exceeds a threshold value, generates a response data packet ( 1200 ) including a volume adjustment command when the difference between the average volume level of the first audio signal and the second audio signal exceeds the threshold value, and transmits the response data packet ( 1200 ). An audio device ( 120 ) transmits the first audio signal, transmits the at least one data packet ( 1000 ) to the sensor ( 110 ), receives the response data packet ( 1200 ), and adjusts an audio level based on the response data packet ( 1200 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a radio receiving apparatus and, more particularly, to a system and method for automatically adjusting the volume of an audio source. 
     BACKGROUND OF THE INVENTION 
     Listening to radio and television broadcasts, whether they are music, news, or discussion-based programming, consumes a large amount of time of the average individual. As people&#39;s lives become busier, there is more of a tendency for multi-tasking. It is quite common for an individual to perform one or more tasks while watching television or listening to the radio. These tasks may involve the individual moving from one location to another (e.g., from the living room to the kitchen). As a result, the individual may be forced to constantly adjust the audio level of the radio or television in order to maintain a comfortable listening level. 
     For example, suppose that a person is listening to a radio or stereo that is playing from a fixed location, such as the living room. As the listener moves throughout the house, the perceived volume at the listener&#39;s location does not remain constant but varies based on the listener&#39;s distance from the audio source. It would be impractical to constantly go back to the radio or stereo system to manually adjust the volume to retain a relatively constant volume as perceived by the listener as he or she moves throughout the house. 
     As another example, suppose that an automobile driver is listening to the car radio while driving. The noise level inside the car is constantly changing. For example, most drivers find that they have to adjust the volume of the radio to different levels as the car changes from highway to city driving speeds. As a result, the automobile radio listener is repeatedly required to manually adjust the volume of the radio to keep it at a perceived constant volume. 
     Suppose, as a further example, that a telephone with hands-free speaker operation is being used by a consumer in the kitchen of a house. As the consumer moves away from the telephone and moves about the kitchen, it may become difficult to hear the caller out of the telephone&#39;s speaker due to either the distance from the telephone or the noise in the kitchen, or both. 
     Accordingly, there is a need in the art for a system and method that will allow the perceived volume of an audio source to remain at a constant level irrespective of a listener&#39;s location. 
     SUMMARY OF THE INVENTION 
     Systems and methods consistent with the present invention address this and other needs by providing a mechanism through which an audio source and an associated local sensor can maintain a constant perceived volume level for a user in close proximity to the local sensor. 
     In accordance with the purpose of this invention as embodied and broadly described herein, a method adjusts an audio level of an audio device. The method includes receiving a first audio signal from the audio device; receiving a data packet from the audio device, the data packet comprising a second audio signal; determining whether a difference between the first audio signal and the second audio signal exceeds a threshold value; and adjusting the audio level of the audio device when the difference between the first audio signal and the second audio signal exceeds the threshold value. 
     In another implementation consistent with the present invention, a system for adjusting an audio level includes a sensor and an audio device. The sensor receives at least one first audio signal, generates a data packet, the data packet comprising the at least one first audio signal, and transmits the data packet. The audio device receives the data packet, retrieves at least one second audio signal, determines average volume levels of the at least one first audio signal and the at least one second audio signal, multiplies the average volume level of the at least one second audio signal with a volume setting value to produce an adjusted average volume level, compares a difference between the average volume level of the first audio signal and the adjusted average volume level to a threshold value, and adjusts the audio level when the difference exceeds the threshold value. 
     In yet another implementation consistent with the present invention, a computer-readable medium having a packet data structure is provided. The packet data structure includes a volume setting field that stores a value representing a volume setting of an audio device and an audio sample field that stores at least one audio sample. 
     In still yet another implementation consistent with the present invention, a computer-readable medium having a packet data structure is provided. The packet data structure includes a destination address field that stores a destination address and a volume adjustment command field that stores a value indicating that a volume of an audio device is to be adjusted. 
     In yet a further implementation consistent with the present invention, a method adjusts an audio level of an audio device. The method includes receiving a first audio signal, the first audio signal comprising a plurality of sub-bands; receiving a data packet, the data packet comprising a second audio signal comprising a plurality of sub-bands; determining, for each sub-band, whether a difference between a sub-band of the first audio signal and a corresponding sub-band of the second audio signal exceeds a threshold value; and adjusting the audio level of a sub-band at the audio device when the difference between a sub-band of the first audio source and the corresponding sub-band of the second audio signal exceeds the threshold value. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, explain the invention. In the drawings, 
         FIG. 1  illustrates an exemplary system in which systems and methods consistent with the present invention may be implemented; 
         FIG. 2  illustrates an exemplary configuration of the elements of the local sensor of  FIG. 1 ; 
         FIG. 3  illustrates an exemplary configuration of the elements of the audio source of  FIG. 1 ; 
         FIGS. 4–9  illustrate an exemplary process, consistent with the present invention, for maintaining a constant perceived audio level at a user; 
         FIG. 10  illustrates an exemplary configuration, consistent with the present invention, of a data packet generated by audio source; 
         FIG. 11  illustrates an exemplary comparison operation consistent with the present invention; 
         FIG. 12  illustrates an exemplary configuration, consistent with the present invention, for the data packet transmitted by local sensor; 
         FIGS. 13–17  an alternative exemplary process, consistent with the present invention, for maintaining a constant perceived audio level at a user; and 
         FIG. 18  an exemplary configuration, consistent with the present invention, for the data packet transmitted by local sensor. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of implementations consistent with the present invention refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims and equivalents. 
     Implementations consistent with the present invention provide a process by which an audio level at a user may be maintained at a constant level. A local sensor is positioned in close proximity to the user. The local sensor interacts with the audio source in order to adjust the volume level of the audio source so that the user perceives a constant audio level. 
     Exemplary System Configuration 
       FIG. 1  illustrates an exemplary system  100  in which systems and methods, consistent with the present invention, for maintaining a constant perceived audio level may be implemented. System  100  includes a local sensor  110  and an audio source  120 . A single local sensor  110  and audio source  120  have been shown for simplicity. It will be appreciated that the techniques described herein are equally applicable to systems having multiple local sensors  110  and audio sources  120 . 
     Local sensor  110  may include components for receiving sound waves, performing calculations on audio signals, and receiving and transmitting data packets to other devices or systems, such as audio source  120 . Local sensor  110  may be employed as a small device attached to a listener&#39;s body, such as a watch-like device, a pager-like device, or a small microphone-like unit clipped to one&#39;s clothing. Alternately, local sensor  110  may be incorporated into a personal electronic device, a piece of clothing worn by a listener, or may be mounted near a listener, such as in an automobile or airplane. 
     Audio source  120  may include components for broadcasting audio signals in the form of sound waves and transmitting and receiving data packets to/from other devices or systems, such as local sensor  110 . Audio source  120  may include the components of a portable personal radio, a stereo system, a car radio, an intercom system, or any other audio device. Audio source  120  may also include any device that broadcasts audio signals of any nature to a listener, such as a computer-like device or a telephone-like device. 
     Exemplary Local Sensor 
       FIG. 2  illustrates an exemplary local sensor  110  configuration consistent with the present invention. In  FIG. 2 , the local sensor  110  includes a power supply  210 , a communications interface  220 , a central processing unit (CPU)  230 , a memory  240 , a converter  250 , and an input device  260 . 
     The power supply  210  may include all the components necessary to supply local sensor  110  with operating power. Power supply  210  may include a battery, fuel cell, solar collector, A/C adapter, or any other device capable of powering the components of local sensor  110 . Alternately, power supply  210  may include a combination of devices capable of supplying power to local sensor  110 . 
     The communications interface  220  may include any transceiver-like mechanism that enables local sensor  110  to communicate with other devices and/or systems, such as audio source  120 , via a wired, wireless, optical, or any other type of connection. For example, communications interface  220  may include a modem or an Ethernet interface to a network. In an implementation consistent with the present invention, communications interface  220  may include an antenna, radio frequency (RF) transceiver, and modem by which local sensor  110  may transmit and receive data packets. 
     The CPU  230  may include any type of conventional processor or microprocessor that interprets and executes instructions in a well-known manner. Alternately, CPU  230  may consist of multiple processors or microprocessors, or some combination thereof. In general, CPU  230  may control the operation of local sensor  110 . 
     The memory  240  may include a random access memory (RAM) or another type of dynamic storage device that stores information, such as information associated with the audio signals and data packets received by the local sensor, and instructions for execution by the CPU  230 . In addition to RAM, memory  240  may also include a read only memory (ROM) or another type of static storage device that stores static information and instructions for use by the CPU  230 , and/or some type of magnetic or optical recording medium and its corresponding drive. 
     The converter  250  may include components necessary to translate audio signals from an analog format to a digital format in a well-known manner. The input device  260 , which may interact directly with converter  250 , may include any conventional mechanism that allows local sensor  110  to receive information, such as a keypad, a mouse, a microphone, and the like. 
     Local sensor  110  operates in response to CPU  230  executing sequences of instructions contained in a computer-readable medium. A computer-readable medium may include one or more memory devices or carrier waves. Execution of the sequences of instructions causes CPU  230  to perform process steps that will be described hereafter. 
     In alternate embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the present invention. Thus, the present invention is not limited to any specific combination of hardware circuitry, software, and/or firmware. 
     Exemplary Audio Source 
       FIG. 3  illustrates an exemplary audio source  120  configuration consistent with the present invention. In  FIG. 3 , the audio source  120  includes a CPU  310 , a memory  315 , a volume input device  320 , a volume controller  325 , a converter  330 , a communications interface  335 , a reactivity input device  340 , a reactivity controller  345 , an amplifier  350 , and an audio output device  355 . 
     The CPU  310  may include any type of conventional processor or microprocessor that interprets and executes instructions. Alternately, CPU  310  may consist of multiple processors or microprocessors, or some combination thereof. In general, CPU  310  may control the operation of audio source  120 . 
     The memory  315  may include a RAM or another type of dynamic storage device that stores information, such as data packets, and instructions for execution by the CPU  310 . In addition to RAM, memory  315  may include a read only memory (ROM) or another type of static storage device that stores static information and instructions for use by the CPU  310 , and/or some type of magnetic or optical recording medium and its corresponding drive. 
     Volume input device  320  may include a user interface for adjusting the volume of the audio emanating from audio source  120 . Volume input device  320  may consist of a dial, switch, or button that can be manually adjusted by a listener. In other applications, volume input device  320  may consist of an audio input device that receives verbal commands or an input device that receives signals transmitted from a remote control. Volume controller  325  may include one or more components that allow CPU  310  to sense the setting of volume input device  320 . 
     Converter  330  may include all the components necessary to translate audio signals from an analog format to a digital format in a well-known manner. The communications interface  335  may include any transceiver-like mechanism that enables audio source  120  to communicate with other devices and/or systems, such as local sensor  110 , via a wired, wireless, optical, or any other type of connection. For example, communications interface  335  may include a modem or an Ethernet interface to a network. In an implementation consistent with the present invention, communications interface  335  may include an antenna, radio frequency (RF) transceiver, and modem by which audio source  120  may transmit and receive data packets. 
     Reactivity input device  340  may include a user interface that allows a listener to adjust the rate at which the volume of audio source  120  is automatically changed in either a positive or negative direction. As used herein, a positive change in the volume of audio source  120  causes the sound level at the output of audio source  120  to increase (i.e. become louder) in contrast a negative change in the volume of audio source  120  causes the outputted sound to decrease (i.e. become quieter). Reactivity input device  340  may, for example, consist of a dial, switch, or button that can be manually adjusted by a listener. In other applications, reactivity input device  340  may consist of an audio input device that receives verbal commands or a device that receives signals transmitted from a remote control. Reactivity controller  345  may include one or more components that allow CPU  310  to sense the setting of reactivity input device  340 . 
     Amplifier  350  may process the audio input signals in a well-known manner and provide them to audio output device  355 . Audio output device  355  may include one or more components that convert audio signals into sound waves in a well-known manner. In an implementation consistent with the present invention, audio output device  355  may include one or more speakers. 
     It will be appreciated that audio source  120  may include additional hardware, software, and/or firmware components (not shown) to perform the functions associated with the operation of various types of audio sources  120 , such as radios, stereos, televisions, telephones, and the like. Audio source  120  operates in response to CPU  310  executing sequences of instructions contained in a computer-readable medium. A computer-readable medium may include one or more memory devices or carrier waves. Execution of the sequences of instructions causes CPU  310  to perform the process steps that will be described hereafter. 
     In alternate embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the above components. Thus, the present invention is not limited to any specific combination of hardware circuitry, software, and/or firmware. 
     Exemplary Processing 
       FIGS. 4–9  illustrate an exemplary process, consistent with the present invention, for maintaining a constant perceived audio level at a user location. Processing begins with the audio source  120  sampling an incoming audio signal, such as the audio input in  FIG. 3  [step  410 ]. Since the audio signal is sampled at its source, the signal may be considered “ideal.” The audio source  120  may store a predetermined number of ideal audio samples in, for example, memory  315  [step  420 ]. As will be appreciated later, the audio source  120  may store a predetermined number of ideal audio samples to allow the local sensor  110  to determine whether a volume adjustment is necessary. If the predetermined number of samples has not yet been stored [step  430 ], the audio source  120  may collect additional samples. 
     When the predetermined number of ideal audio samples has been collected [step  430 ], the audio source  120  may obtain the current volume setting [step  440 ]. The audio source  120  may obtain the current volume setting from the volume controller  325 . Once obtained, the audio source  120  may store that information in memory  315  [step  450 ]. The audio source  120  may also obtain the current reactivity setting from reactivity controller  345  [step  460 ], and may store that information in memory  315  [step  470 ]. 
     After retrieving the ideal audio samples, the volume setting, and the reactivity setting, the audio source  120  may generate a data packet for transmission to the local sensor  110  [step  480 ].  FIG. 10  illustrates an exemplary configuration, consistent with the present invention, of a data packet  1000  generated by audio source  120 . As illustrated, the data packet  1000  may include a header  1020  and a data field  1030 . 
     The header  1020  may contain the overhead information associated with the process of transmitting data over a communications channel. The header  1020  may include a source address  1022  and a destination address  1024 . Source address  1022  may include a unique identifier that represents the address of the source transmitting data packet  1000 . In this case, the source address may identify the audio source  120 . Destination address  1024  may include a unique identifier that represents the address of the recipient of data packet  1000  (i.e., local sensor  110 ). It will be appreciated that a typical packet header may include additional fields (not shown), such as a length field, an error correction field, and the like. 
     Data field  1030  may represent the portion of data packet  1000  that contains the actual data for which the transmission is being made. Data field  1030  may include multiple fields of information, such as a volume setting  1032 , a reactivity setting  1034 , and an ideal audio sample  1036 . The volume setting  1032  may include an indication of a current setting of volume input device  320 . The reactivity setting  1034  may include an indication of a current setting of reactivity input device  340 . The ideal audio sample  1036  may contain the ideal audio signals sampled by audio source  120 . 
     While a packet structure having a header has been set forth, it will be appreciated that the above description is equally applicable to a packet structure having a trailer or any other similar or equivalent format. 
     After generating the data packet  1000 , audio source  120  may then transmit the data packet  1000  to the local sensor  110  [step  490 ]. The data packet  1000  may be transmitted via communications interface  335  to the local sensor  110  in any well-known manner, such as by any wireless, wired, or optical technique. 
     The local sensor  110  may receive data packet  1000  via, for example, communications interface  220  [step  510 ] ( FIG. 5 ). The local sensor  110  may then extract the ideal audio sample  1036  transmitted in data packet  1000  [step  520 ] and store this information in memory  240  [step  530 ]. 
     Local sensor  110  may extract the volume setting information  1032  transmitted in data packet  1000  [step  540 ]. As indicated above, this information may represent a current volume setting value of the volume input device  320 . Local sensor  110  may store the volume setting value in, for example, memory  240  [step  550 ]. 
     Local sensor  110  may extract the reactivity setting information  1034  transmitted in data packet  1000  [step  560 ]. As indicated above, this information may represent a current reactivity setting value of the reactivity input device  340 . Local sensor  110  may store the reactivity setting value in memory  240  [step  570 ]. 
     To determine whether a volume adjustment is necessary, the local sensor  110  may sample the audio signals transmitted by audio source  120  via its audio output device  355  [step  610 ] ( FIG. 6 ). The local sensor  110  may receive the audio samples via, for example, its input device  260 . These audio samples are referred to hereinafter as “local audio samples.” The local sensor  110  may then store the local audio samples in, for example, memory  240  [step  620 ]. 
     The local sensor  110  may determine the best correlation between the local audio samples received through input device  260 , and the ideal audio samples received in data packet  1000  [step  630 ]. In general, there may be some delay between the two samples, and the local audio sample may be corrupted from the ideal audio samples due to extraneous noise picked up by the local sensor&#39;s input device  260 . The local sensor  110  may use any of the conventional techniques well known in the art to correlate or line-up the two corresponding samples. The local sensor  110  may then determine the average volume of the ideal audio samples [step  640 ] and the local audio samples [step  650 ] in a well-known manner. The average volumes may be determined in any number of classical ways, such as simple averaging, time series averaging, or any other standard method. 
     The local sensor  110  may multiply the average value for the ideal audio samples by the volume setting value  1032  received in the data packet  1000  in order to adjust the desired value to a level consistent with the user&#39;s volume setting [step  640 ]. 
     The local sensor  110  may then compare the average volumes of the ideal audio sample and the local audio sample in a well-known manner [step  710 ] ( FIG. 7 ).  FIG. 11  illustrates an exemplary comparison operation consistent with the present invention. As illustrated, the local sensor  110  determines an average volume level  1110  for the ideal audio sample received in data packet  1000 . The local sensor  110  also determines an average volume level  1120  for the local audio samples captured by input device  260 . The local sensor  110  may then compare the two average volumes to arrive at a delta volume  1130  as illustrated by the difference between the dashed lines in  FIG. 11 . The delta volume may represent the average difference between the ideal audio sample and the local audio sample. 
     Local sensor  110  may then determine if the average difference between the ideal audio sample and the local audio sample (i.e., the delta volume  1130 ) is greater than a threshold value [step  720 ]. The threshold value may represent a value, below which it is determined that the two audio samples are close enough such that no volume adjustments are necessary. This threshold value may be set, for example, by the user or manufacturer of local sensor  110 . 
     If the local sensor  110  determines that the average difference between the local audio samples and the ideal audio samples is below or less than the threshold value, then no immediate volume adjustment is necessary and local sensor  110  may return to step  510  [step  730 ]. If the average difference between the local audio samples and the ideal audio samples is greater than the threshold value, local sensor  110  may set a flag or indicator that a volume adjustment at audio source  120  is warranted [step  740 ]. The local sensor  110  may store this flag in memory  240  until needed. 
     Local sensor  110  may then determine if the average volume of the local audio signal is less than the average volume of the ideal audio sample [step  750 ]. This may be determined, for example, by subtracting one average volume from the other. If the average volume of the local audio sample is less than the average volume of the ideal audio sample, then local sensor  110  may set a flag to indicate that a volume increase is warranted [step  760 ]. If the average volume of the local audio sample is greater than the average volume of the ideal audio sample, then local sensor  110  may set a flag to indicate that a volume decrease is warranted [step  770 ]. 
     Once local sensor  110  determines that a volume adjustment is necessary, the local sensor  110  may then determine if it is time to adjust the volume of audio source  120  [step  810 ] ( FIG. 8 ). The local sensor  110  may query memory  240  to obtain the reactivity setting  1034  that was transmitted from the audio source  120  in data packet  1000 . The local sensor  110  may then determine how long it has been since the last volume adjustment command has been sent to the audio source  120 , and based on that time along with the reactivity setting  1034  may determine if it is time to send the another volume adjustment command. If a predetermined amount of time has not elapsed since the last volume adjustment, local sensor  110  may delay any future adjustments until the appropriate time. 
     If the delay since the last volume adjustment command was sent is consistent with the value of the reactivity setting, then local sensor  110  may determine if a flag is set indicating that either an increase or decrease in the volume is warranted [step  820 ]. If a flag is not set, indicating that no volume adjustment is necessary, then local sensor  110  may wait until the end of the next time period before looking again for the flag indicating whether an adjustment is necessary. 
     If a flag is set to indicate that a volume adjustment is necessary, then local sensor  110  may generate a data packet containing the volume adjustment command [step  830 ].  FIG. 12  illustrates an exemplary configuration  1200 , consistent with the present invention, for the data packet transmitted by local sensor  110 . As illustrated, data packet  1200  may include a header  1220  and a data field  1230 . 
     The header  1220  may contain overhead information associated with the process of transmitting data over a communications channel. As illustrated, the header  1220  may include a source address  1222  and a destination address  1224 . Source address  1222  may include a unique identifier that represents the address of the source transmitting data packet  1200 . In this case, the source address would identify the local sensor  110 . Destination address  1224  may include a unique identifier that represents the address of the recipient of data packet  1200  (i.e., audio source  120 ). It will be appreciated that a typical packet header may include additional fields (not shown), such as a length field, an error correction field, and the like. 
     Data field  1230  may represent the portion of data packet  1200  that contains the actual data for which the transmission is being made. Data field  1230  may include, for example, a volume adjustment command  1232 . The volume adjustment command  1232  may include a command to either increase or decrease the volume of audio source  120 . The volume adjustment command  1232  may include a value (not shown) representing the amount that the volume of audio source  120  is to be adjusted. 
     While a packet structure having a header has been set forth, it will be appreciated that the above description is equally applicable to a packet structure having a trailer or any other similar or equivalent format. 
     Local sensor  110  may then transmit data packet  1200  to audio source  120  [step  840 ]. The local sensor  110  may transmit the data packet  1200  in any well-known manner, such as by any wireless, wired, or optical technique. 
     The audio source  120  may receive the data packet  1200  from local sensor  110  via, for example, communications interface  335  [step  910 ] ( FIG. 9 ). Audio source  120  may extract the volume adjustment command  1232  from the data packet  1200  in a well-known manner [step  920 ]. After extracting the volume adjustment command  1232 , audio source  120  may determine whether the volume needs to be increased [step  930 ]. For illustration purposes, the volume adjustment command  1232  could consist of a single binary digit. A value of “0” may indicate that the volume needs to be decreased, and a value of “1” may indicate to audio source  120  that the volume needs to be increased. 
     If audio source  120  determines that an increase in volume is warranted, the audio source  120  may increase the volume incrementally [step  940 ]. CPU  310  may increase the gain of amplifier  350  and hence the volume of audio output device  355  which may, for example, consist of one or more standard speakers. If audio source  120  determines that a decrease in volume is warranted, the audio source  120  may decrease the volume incrementally [step  950 ]. In this case, for example, CPU  310  may reduce the gain of amplifier  350 , and hence the volume of audio output device  355 . 
     Alternative Exemplary Processing 
       FIGS. 13–17  illustrate an alternative exemplary process, consistent with the present invention, for maintaining a constant perceived audio level at a user. Processing may begin with the audio source  120  sampling an incoming audio signal, such as the audio input in  FIG. 3  [step  1310 ]. Since the audio signal is sampled at its source, the signal may be considered “ideal.” The audio source  120  may store a predetermined number of ideal audio samples in, for example, memory  315  [step  1320 ]. As will be appreciated later, the audio source  120  may store a predetermined number of ideal audio samples to determine whether a volume adjustment is necessary. If the predetermined number of samples has not been stored [step  1330 ], the audio source  120  may collect additional samples. 
     When the predetermined number of ideal audio samples has been collected [step  1330 ], the audio source  120  may obtain the current volume setting [step  1340 ]. The audio source  120  may obtain the current volume setting from the volume controller  325 . Once obtained, the audio source  120  may store that information in memory  315  [step  1350 ]. The audio source  120  may also obtain the current reactivity setting from reactivity controller  345  [step  1360 ], and may store that information in memory  315  [step  1370 ]. Once this information is stored, the audio source  120  may transmit a request to the local sensor  110  for local audio sample [step  1380 ]. 
     The local sensor  110  may receive the request from the audio source  120  [step  1410 ] ( FIG. 14 ). In response thereto, the local sensor  110  may sample local audio signals in the form of sound waves from audio source  120  via, for example input device  260  [step  1420 ] ( FIG. 14 ). In other implementations consistent with the present invention, the local sensor  110  may automatically sample the local audio signals at predetermined periods of time. The local sensor  110  may store the local audio samples in memory  240  [step  1430 ]. 
     Local sensor  110  may then generate a data packet containing the local audio samples [step  1440 ].  FIG. 18  illustrates an exemplary configuration  1800 , consistent with the present invention, for the data packet transmitted by local sensor  110 . As illustrated, data packet  1800  may include a header  1820  and a data field  1830 . 
     The header  1820  may contain overhead information associated with the process of transmitting data over a communications channel. As illustrated, the header  1820  may include a source address  1822  and a destination address  1824 . Source address  1822  may include a unique identifier that represents the address of the source transmitting the data packet. In this case, the source address would identify the local sensor  110 . Destination address  1824  may include a unique identifier that represents the address of the recipient of data packet  1800  (i.e., audio source  120 ). It will be appreciated that a typical packet header may include additional fields (not shown), such as a length field, an error correction field, and the like. 
     Data field  1830  may represent the portion of data packet  1800  that contains the actual data for which the transmission is being made. Data field  1830  may include, for example, the local audio samples  1832 . The local audio samples  1832  may include the audio samples received by local sensor  110  from audio source  120  in the form of sound waves. These samples may be received, for example, via input device  260 , and may represent the state of the local audio signals in the proximity of the user. 
     While a packet structure having a header has been set forth, it will be appreciated that the above description is equally applicable to a packet structure having a trailer or any other similar or equivalent format. 
     Local sensor  110  may then transmit data packet  1800  to audio source  120  [step  1450 ]. The local sensor  110  may transmit the data packet  1800  in any well-known manner, such as by any wireless, wired, or optical technique. 
     The audio source  120  may receive the data packet  1800  from local sensor  110  via, for example, communications interface  335  [step  1510 ] ( FIG. 15 ). Audio source  120  may extract the local audio samples  1832  from the data packet  1800  in a well-known manner, and may store this information in memory  315  [step  1520 ]. 
     The audio source  120  may then determine the best correlation between the local audio samples and the ideal audio samples now stored in memory  315  [step  1530 ]. In general, there may be some delay between the two samples, and the local audio sample may be corrupted from the ideal audio samples due to extraneous noise picked up by the local sensor&#39;s input device  260 . The audio source  120  may use any of the conventional techniques well known in the art to correlate or line-up the two corresponding samples. The audio source  120  may then determine the average volume of the ideal audio samples [step  1540 ] and the local audio samples [step  1550 ] in a well-known manner. The average volumes may be determined in any number of classical ways, such as simple averaging, time series averaging, or any other standard method. The audio source  120  may multiply the average value for the ideal audio samples by the volume setting value previously stored in memory  315 , or obtained from the volume controller  325 , in order to adjust the desired value to a level consistent with the user&#39;s volume setting [step  1540 ]. 
     The audio source  120  may then compare the average volumes of the ideal audio sample and the local audio sample in a well-known manner [step  1610 ] ( FIG. 16 ).  FIG. 11 , as described previously, illustrates an exemplary comparison operation consistent with the present invention. As illustrated, the audio source  120  determines an average volume level  1110  for the ideal audio sample. The audio source  120  also determines an average volume level  1120  for the local audio samples captured by local sensor  110  and transmitted to audio source  120  in data packet  1800 . The audio source  120  may then compare the two average volumes to each other to arrive at a delta volume  1130  as illustrated by the difference between the dashed lines in  FIG. 11 . The delta volume may represent the average difference between the ideal audio sample and the local audio sample. 
     Audio source  120  may then determine if the average difference between the ideal audio sample and the local audio sample (i.e., the delta volume  1130 ) is greater than a threshold value [step  1620 ]. The threshold value may represent a value, below which it is determined that the two audio samples are close enough such that no volume adjustments are necessary. This threshold value may be set, for example, by the user or manufacturer of audio source  120 . 
     If the audio source  120  determines that the average difference between the local audio samples and the ideal audio samples is below the threshold value, then no immediate volume adjustment is necessary and audio source  120  may return to step  1310  [step  1630 ]. If the average difference between the local audio samples and the ideal audio samples is greater than the threshold value, audio source  120  may set a flag or indicator that a volume adjustment at audio source  120  is warranted [step  1640 ]. The audio source  120  may store this flag in memory  315  until needed. 
     Audio source  120  may then determine if the average volume of the local audio signal is less than the average volume of the ideal audio sample [step  1650 ]. This may be determined, for example, by subtracting one average volume from the other. If the average volume of the local audio sample is less than the average volume of the ideal audio sample, then audio source  120  may set a flag to indicate that a volume increase is warranted [step  1660 ]. If the average volume of the local audio sample is greater than the average volume of the ideal audio sample, then audio source  120  may set a flag to indicate that a volume decrease is warranted [step  1670 ]. 
     Once audio source  120  determines that a volume adjustment is necessary, the audio source  120  may then determine if it is time to adjust its volume [step  1710 ] ( FIG. 17 ). The audio source  120  may query memory  315  to obtain the reactivity setting stored there. The audio source  120  may then determine how long it has been since the last volume adjustment was made, and based on that time, along with the reactivity setting, may determine if it is time to make another volume adjustment. If a predetermined amount of time has not elapsed since the last volume adjustment, audio source  120  may delay any future adjustments until the appropriate time. If the delay since the last volume adjustment is consistent with the value of the reactivity setting, then audio source  120  may determine if a flag is set indicating that either an increase or decrease in the volume is warranted [step  1720 ]. If a flag is not set, indicating that no volume adjustment is necessary, then audio source  120  may wait until the end of the next time period before looking again for the flag indicating whether an adjustment is necessary. 
     If a flag is set indicating that a volume adjustment is necessary, then audio source  120  may then determine whether the volume needs to be increased [step  1730 ]. Audio source  120  may, for example, query memory  315  to determine if a flag is set to indicate that an increase in volume is warranted. If audio source  120  determines that an increase in volume is warranted, then audio source  120  may increase the volume incrementally [step  1740 ]. CPU  310  may increase the gain of amplifier  350  and hence the volume of audio output device  355  which may, for example, consist of one or more standard speakers. 
     If audio source  120  determines that a decrease in volume is warranted, then audio source  120  may decrease the volume incrementally [step  1750 ]. Audio source  120  may, for example, query memory  315  to determine if a flag is set to indicate that a decrease in volume is warranted. In this case, for example, CPU  310  may reduce the gain of amplifier  350 , and hence the volume of audio output device  355 . 
     CONCLUSION 
     Systems and methods, consistent with the present invention, provide a mechanism by which an audio source can maintain a constant perceived volume level at a local sensor. A local sensor in close proximity to a user provides feedback to the audio source to raise, lower, or maintain its volume level so as to maintain that perceived constant volume level at the local sensor. 
     The foregoing description of exemplary embodiments of the present invention provides illustration and description, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. For example, while the above-described processing is directed to adjusting the volume of audio signals, it will be appreciated that the present invention is equally applicable to adjusting sub-bands of an audio signal. In such an implementation, the local sensor may sample audio signals from each of a plurality of sub-bands. The local sensor may then instruct the audio source whether an adjustment of any or all of the sub-bands is necessary. This would allow, for example, local sensor to boost the bass of the audio source, while keeping the treble constant. 
     While series of steps have been described with regard to  FIGS. 4–9  and  13 – 17 , the order of the steps may be varied in other implementations consistent with the present invention. No element, step, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. 
     The scope of the invention is defined by the claims and their equivalents.