Patent Publication Number: US-10325617-B2

Title: Electronic device and method for classifying voice and noise

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 U.S.C. § 119 to a Korean patent application filed on Feb. 19, 2016 in the Korean Intellectual Property Office and assigned Serial number 10-2016-0020049, the disclosure of which is incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates generally to technology to distinguish between a voice interval and a noise interval of an audio signal. 
     BACKGROUND 
     With the development of electronic technologies, various types of electronic products are being developed and distributed. In particular, an electronic device having a variety of functions, such as a smartphone, a tablet PC, a wearable device, or the like is being widely supplied nowadays. The electronic device may provide a call function to a user. In addition, the electronic device may remove a noise from a signal to improve call quality. 
     Generally, a conventional electronic device detects a voice and a noise from the signal by using only a characteristic such as energy, a frequency, or the like of the signal that is input to a microphone. In this case, it may be difficult to detect a non-stationary noise of which a magnitude or a frequency is rapidly changed. Furthermore, if a signal to noise ratio (SNR) of the signal is low, it is very difficult to detect a noise. 
     SUMMARY 
     Various example of the present disclosure address at least the above-mentioned problems and/or disadvantages and provide at least the advantages described below. Accordingly, an example aspect of the present disclosure provides an electronic device and a method that are capable of accurately detecting a voice and a noise from a signal, in which a non-stationary noise is included, or a signal of which SNR is low. 
     In accordance with an example aspect of the present disclosure, an electronic device includes a first microphone configured to receive a sound, which is generated for a specific time period, from the outside, a second microphone, which is disposed at a location spaced apart from the first microphone and which is configured to receive the sound, an audio converter comprising audio converting circuitry, and a processor electrically connected with the first microphone, the second microphone, and the audio converter. The processor is configured to convert the sound, which is obtained from the first microphone, into a first signal and to convert the sound, which is obtained from the second microphone, into a second signal, using the audio converter, and to determine the sound, which is generated for the specific time period, as a voice or a noise based on a frequency-related correlation between the first signal and the second signal. 
     In accordance with an example aspect of the present disclosure, a voice and noise classification method of an electronic device including a first microphone and a second microphone includes converting a sound, which is obtained from the first microphone for a specific time period, into a first signal, converting the sound, which is obtained from the second microphone disposed at a location spaced apart from the first microphone, into a second signal, and determining the sound, which is generated for the specific time period, as a voice or a noise based on a frequency-related correlation between the first signal and the second signal. 
     In accordance with an example aspect of the present disclosure, an electronic device includes a first microphone that receives a sound, which is generated for a specific time period, from the outside, a second microphone, which is disposed at a location spaced apart from the first microphone and which receives the sound, an audio converter comprising audio converting circuitry, and a processor electrically connected with the first microphone and the second microphone. The processor is configured to convert the sound, which is obtained from the first microphone, into a first signal and to convert the sound, which is obtained from the second microphone, into a second signal, using the audio converter, to determine the sound, which is generated for the specific time period, as a voice if a value associated with a difference between energy of the first signal and energy of the second signal is greater than a specific energy value and a value associated with at least one of spectral variance of the first signal or spectral variance of the second signal is greater than a specified variance value, and to determine the sound, which is generated for the specified time period, as the voice or a noise based on a frequency-related correlation between the first signal and the second signal if the value associated with a difference between the energy of the first signal and the energy of the second signal is less than the specific energy value or the value associated with at least one of the spectral variance of the first signal or the spectral variance of the second signal is less than the specified variance value. 
     Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and attendant advantages of the present disclosure will be more apparent and readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings, in which like reference numerals refer to like elements, and wherein: 
         FIG. 1  is a perspective view of an example electronic device, according to an example embodiment; 
         FIG. 2  is a block diagram illustrating an example configuration of an electronic device, according to an example embodiment; 
         FIG. 3  is a flowchart illustrating an example voice and noise classification method of an electronic device, according to an example embodiment; 
         FIG. 4  is a flowchart illustrating an example voice and noise classification method of an electronic device, according to an example embodiment; 
         FIGS. 5A and 5B  are graphs illustrating an example comparison result in which a voice and a noise is recognized by an electronic device, according to an example embodiment; 
         FIGS. 6A and 6B  are graphs illustrating an example comparison result in which a signal is processed by an electronic device, according to an example embodiment; 
         FIGS. 7A and 7B  are tables illustrating an example sound quality comparison results of a signal processed by an electronic device, according to an example embodiment; 
         FIG. 8  is a diagram illustrating an example electronic device in a network environment, according to various example embodiments; 
         FIG. 9  is a block diagram illustrating an example electronic device, according to an example embodiment; and 
         FIG. 10  is a block diagram illustrating an example program module, according to various example embodiments. 
     
    
    
     Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
     DETAILED DESCRIPTION 
     Various example embodiments of the present disclosure may be described with reference to accompanying drawings. Accordingly, those of ordinary skill in the art will recognize that modifications, equivalents, and/or alternatives to the various example embodiments described herein can be variously made without departing from the scope and spirit of the present disclosure. With regard to description of drawings, similar elements may be marked by similar reference numerals. 
     In the disclosure disclosed herein, the expressions “have”, “may have”, “include” and “comprise”, or “may include” and “may comprise” used herein indicate existence of corresponding features (e.g., elements such as numeric values, functions, operations, or components) but do not exclude presence of additional features. 
     In the disclosure disclosed herein, the expressions “A or B”, “at least one of A or/and B”, or “one or more of A or/and B”, and the like used herein may include any and all combinations of one or more of the associated listed items. For example, the term “A or B”, “at least one of A and B”, or “at least one of A or B” may refer to all of the case (1) where at least one A is included, the case (2) where at least one B is included, or the case (3) where both of at least one A and at least one B are included. 
     The terms, such as “first”, “second”, and the like used herein may refer to various elements of various embodiments of the present disclosure, but do not limit the elements. For example, a first user device and a second user device indicate different user devices regardless of the order or priority. For example, without departing the scope of the present disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. 
     It will be understood that when an element (e.g., a first element) is referred to as being “(operatively or communicatively) coupled with/to” or “connected to” another element (e.g., a second element), it may be directly coupled with/to or connected to the other element or an intervening element (e.g., a third element) may be present. In contrast, when an element (e.g., a first element) is referred to as being “directly coupled with/to” or “directly connected to” another element (e.g., a second element), it should be understood that there are no intervening element (e.g., a third element). 
     According to the situation, the expression “configured to” used herein may be used interchangeably with, for example, the expression “suitable for”, “having the capacity to”, “designed to”, “adapted to”, “made to”, or “capable of”. The term “configured to” must not mean only “specifically designed to” in hardware. Instead, the expression “a device configured to” may refer to a situation in which the device is “capable of” operating together with another device or other components. For example, a “processor configured to perform A, B, and C” may refer, for example, to a dedicated processor (e.g., an embedded processor) for performing a corresponding operation or a generic-purpose processor (e.g., a central processing unit (CPU) or an application processor) which may perform corresponding operations by executing one or more software programs which are stored in a memory device. 
     Terms used in the present disclosure are used to describe specified embodiments and are not intended to limit the scope of the present disclosure. The terms of a singular form may include plural forms unless otherwise specified. All the terms used herein, which include technical or scientific terms, may have the same meaning that is generally understood by a person skilled in the art. It will be further understood that terms, which are defined in a dictionary and commonly used, should also be interpreted as is customary in the relevant related art and not in an idealized or overly formal detect unless expressly so defined herein in various embodiments of the present disclosure. In some cases, even if terms are terms which are defined in the specification, they may not be interpreted to exclude embodiments of the present disclosure. 
     According to various embodiments of the present disclosure, an electronic device may include at least one of, for example, smartphones, tablet personal computers (PCs), mobile phones, video telephones, electronic book readers, desktop PCs, laptop PCs, netbook computers, workstations, servers, personal digital assistants (PDAs), portable multimedia players (PMPs), Motion Picture Experts Group (MPEG-1 or MPEG-2) Audio Layer 3 (MP3) players, mobile medical devices, cameras, or wearable devices, or the like, but is not limited thereto. According to various embodiments, a wearable device may include at least one of an accessory type of a device (e.g., a timepiece, a ring, a bracelet, an anklet, a necklace, glasses, a contact lens, or a head-mounted-device (HMD)), one-piece fabric or clothes type of a device (e.g., electronic clothes), a body-attached type of a device (e.g., a skin pad or a tattoo), or a bio-implantable type of a device (e.g., implantable circuit), or the like, but is not limited thereto. 
     According to another embodiment, the electronic devices may be home appliances. The home appliances may include at least one of, for example, televisions (TVs), digital versatile disc (DVD) players, audios, refrigerators, air conditioners, cleaners, ovens, microwave ovens, washing machines, air cleaners, set-top boxes, home automation control panels, security control panels, TV boxes (e.g., Samsung HomeSync™, Apple TV™, or Google TV™), game consoles (e.g., Xbox™ or PlayStation™), electronic dictionaries, electronic keys, camcorders, electronic picture frames, or the like, but is not limited thereto. 
     According to another embodiment, the electronic device may include at least one of medical devices (e.g., various portable medical measurement devices (e.g., a blood glucose monitoring device, a heartbeat measuring device, a blood pressure measuring device, a body temperature measuring device, and the like)), a magnetic resonance angiography (MRA), a magnetic resonance imaging (MRI), a computed tomography (CT), scanners, and ultrasonic devices), navigation devices, global navigation satellite system (GNSS), event data recorders (EDRs), flight data recorders (FDRs), vehicle infotainment devices, electronic equipment for vessels (e.g., navigation systems and gyrocompasses), avionics, security devices, head units for vehicles, industrial or home robots, automatic teller&#39;s machines (ATMs), points of sales (POSs), or internet of things (e.g., light bulbs, various sensors, electric or gas meters, sprinkler devices, fire alarms, thermostats, street lamps, toasters, exercise equipment, hot water tanks, heaters, boilers, and the like), or the like, but is not limited thereto. 
     According to another embodiment, the electronic devices may include at least one of parts of furniture or buildings/structures, electronic boards, electronic signature receiving devices, projectors, or various measuring instruments (e.g., water meters, electricity meters, gas meters, or wave meters, and the like), or the like, but is not limited thereto. According to various embodiments, the electronic device may be one of the above-described devices or a combination thereof. According to an embodiment, an electronic device may be a flexible electronic device. Furthermore, according to an embodiment of the present disclosure, an electronic device may not be limited to the above-described electronic devices and may include other electronic devices and new electronic devices according to the development of technologies. 
     Hereinafter, according to various embodiments, electronic devices will be described with reference to the accompanying drawings. The term “user” used herein may refer to a person who uses an electronic device or may refer to a device (e.g., an artificial intelligence electronic device) that uses an electronic device. 
       FIG. 1  is a perspective view illustrating an example electronic device, according to an example embodiment of the present disclosure. 
     Referring to  FIG. 1 , according to an embodiment, an electronic device  100  may include a first microphone  111 , a second microphone  112 , and a third microphone  113 . 
     The first microphone  111  may receive a sound from the outside. The sound received by the first microphone  111  may be converted into an electrical signal. The first microphone  111  may be exposed through an upper portion of a housing of the electronic device  100 . For example, the first microphone  111  may be exposed through a side surface of the housing of the electronic device  100 . In  FIG. 1 , it is illustrated that the first microphone  111  is exposed through the side surface of the housing of the electronic device  100 . However, embodiments of the present disclosure are not limited thereto. For example, the first microphone  111  may be exposed through a lower portion of a front surface or a rear surface of the housing of the electronic device  100 . 
     The second microphone  112  may receive the sound at a location that is spaced apart from the first microphone  111 . The second microphone  112  may be located at a distance of, for example, about 10 cm to about 15 cm. In  FIG. 1 , it is illustrated that the second microphone  112  is exposed through the side surface of the housing of the electronic device  100 . However, embodiments of the present disclosure are not limited thereto. For example, the second microphone  112  may be exposed through an upper portion of a front surface or a rear surface of the housing of the electronic device  100 . 
     According to an embodiment, a frequency band of the sound that is determined as a voice may be changed in accordance with a distance between the first microphone  111  and the second microphone  112 . For example, in the case where the distance between the first microphone  111  and the second microphone  112  is within about 10 cm to about 15 cm, a frequency in which the corresponding distance is used as a wavelength may be about 2.3 kHz to about 3.4 kHz, and the sound of 1 kHz or less may be classified into a voice or a noise. 
     The third microphone  113  may disposed at a location that is spaced apart from the first microphone  111  and the second microphone  112 . The third microphone  113  may be configured to receive the sound. A distance between the third microphone  113  and the first microphone  111  and a distance between the third microphone  113  and the second microphone  112  may be different from each other. For example, the third microphone  113  may be exposed through a left end or a right end of the housing of the electronic device  100 . In  FIG. 1 , it is illustrated that the third microphone  113  is exposed through the side surface of the housing of the electronic device  100 . However, embodiments of the present disclosure are not limited thereto. For example, the third microphone  113  may be exposed through a center area of the rear surface of the housing of the electronic device  100 . In  FIG. 1 , it is illustrated that the electronic device  100  includes the third microphone  113 . However, the electronic device  100  may include only the first microphone  111  and the second microphone  112 . 
     The electronic device  100  may receive the sound, which is generated for the same time period, by using each of the first microphone  111  and the second microphone  112  (or the first microphone  111 , the second microphone  112 , and the third microphone  113 ). The electronic device  100  may convert sounds, which is received by the first microphone  111  and the second microphone  112  (or the first microphone  111 , the second microphone  112 , and the third microphone  113 ), into first and second signals (or the first signal, the second signal, and third signal), respectively. The electronic device  100  may determine the sounds as voices or noises based on magnitude squared coherence (MSC) associated with the first signal and the second signal (or the first signal, the second signal, and the third signal). 
     Below, the operation of determining the sound, which is received by the first microphone  111  and the second microphone  112  (or the first microphone  111 , the second microphone  112  and the third microphone  113 ), as a voice or a noise will be described with reference to  FIGS. 2 to 4  in detail. 
       FIG. 2  is a block diagram illustrating an example configuration of an electronic device, according to an example embodiment of the present disclosure. 
     Referring to  FIG. 2 , according to an embodiment, the electronic device  100  may include the first microphone  111 , the second microphone  112 , the third microphone  113 , a memory  120  (e.g., a memory  830  or a memory  930  illustrated in  FIGS. 8 and 9 , respectively), a communication circuit  130 , and a processor (e.g., including processing circuitry)  140  (e.g., a processor  820  or a processor  910  illustrated in  FIGS. 8 and 9 , respectively). 
     The electronic device  100  may be a device that is capable of receiving a sound from the outside. The electronic device  100  may determine the sound, which is received from the outside, as a voice or a noise. For example, the electronic device  100  may be one of various devices, which support a call function or a voice recognition function, such as a smartphone, a tablet PC, a wearable device, a home smart device, and the like, but is not limited thereto. 
     Each of the first microphone  111 , the second microphone  112 , and the third microphone  113  may receive the sound, which is generated for a specific time period, from the outside. Sounds received by the first microphone  111 , the second microphone  112 , and the third microphone  113  may be converted into electrical signals (e.g., a first signal, a second signal, and a third signal), respectively. A specific time period may be a time period including one frame. A specific time period may be a time period including two or more frames. A frame length of an electrical signal may be about 20 msec to about 30 msec. 
     The memory  120  (e.g., the memory  830  or the memory  930 ) may store the electrical signal. If the electrical signal is determined as a voice signal or a noise signal, the memory  120  (e.g., the memory  830  or the memory  930 ) may store the electrical signal together with a flag indicating a voice or a noise. 
     The communication circuit  130  may include various circuitry and communicate with an external device  200 . For example, in the case where the electronic device  100  provides a call function, the communication circuit  130  may send the sounds, which are received by the first microphone  111 , the second microphone  112  and the third microphone  113 , to the external device  200 . As another example, in the case where the electronic device  100  provides a voice recognition function, the communication circuit  130  may send a command corresponding to a voice recognition result to the external device  200 . 
     The processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may include various processing circuitry and be electrically connected with the first microphone  111 , the second microphone  112 , the third microphone  113 , the memory  120  (e.g., the memory  830  or the memory  930 ), and the communication circuit  130 . The processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may control the first microphone  111 , the second microphone  112 , the third microphone  113 , the memory  120  (e.g., the memory  830  or the memory  930  illustrated in  FIGS. 8 and 9 , respectively), and the communication circuit  130 . 
     According to an embodiment, the processor  140  (e.g., the processor  820  or the processor  910 ) may convert the sound, which is obtained from the first microphone  111  for a specific time period (e.g.,  1  frame), into the first signal and may convert the sound, which is obtained from the second microphone  112  for a specific time period, into the second signal, by using an audio converter (not illustrated) included in the electronic device  100 . For example, sounds obtained by the first microphone  111  and the second microphone  112  may be converted first and second analog signals, respectively. The first and second analog signals may be sampled at specific intervals, respectively. Therefore, the first analog signal and the second analog signal may be converted into a first discrete signal and a second discrete signal, respectively. In the case where a sampling rate is 16000 sample/sec, a signal corresponding to one frame may include 320 to 480 samples. For example, the processor  140  (e.g., the processor  820  or the processor  910 ) may obtain the first and second signals being frequency signals by converting the first and second discrete signals into the frequency signals in a frequency domain, respectively. 
     According to an embodiment, in the case where the third microphone  113  is included in the electronic device  100 , the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may convert the sound, which is obtained from the third microphone  113 , into the third signal using the audio converter. For example, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may convert the sound, which is obtained from the third microphone  113 , into the third signal by using the above-mentioned method. 
     According to an embodiment, the processor  140  may determine the sound, which is generated for a specific time period (e.g., one frame), as a voice or a noise based on a frequency-related correlation between the first signal and the second signal. For example, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sound, which is generated for a specific time period (e.g., one frame), as the voice or the noise based on an autocorrelation function of the first signal, an autocorrelation function of the second signal, and a cross-correlation function of the first signal and the second signal. For example, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sound, which is generated for a specific time period (e.g., one frame), as the voice or the noise based on MSC of the first signal and the second signal. If the MSC is greater than a specified value, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sound, which is generated for a corresponding time period, as the voice. If the MSC is less than the specified value, the processor  140  may determine the sound, which is generated for the corresponding time period, as the noise. Favorably, a threshold value of the MSC which is a reference for determining the sound as the voice or the noise may be 0.6 to 0.7. The threshold value of the MSC may be variously changed. The threshold value of the MSC may decrease to reduce the number of times that the voice is misinterpreted as the noise. On the other hand, the threshold value of the MSC may increase to reduce the number of times that the noise is misinterpreted as the voice. In the case where the processor  140  determines the sound, which is generated for a specific time period, as the voice or the noise based on the MSC, the processor  140  (e.g., the processor  820  or the processor  910 ) does not require an initial noise interval to determine the voice or the noise because the processor  140  determines a signal of the corresponding frame as the voice or the noise by using only the signal of one frame. 
     According to an embodiment, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sound, which is generated for a specific time period, as the voice or the noise based on at least one or more of a correlation between the first signal and the second signal, a correlation between the second signal and the third signal, or a correlation between the third signal and the first signal. For example, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sound, which is generated for a specific time period, as the voice or the noise based on MSC of the first signal and the second signal, MSC of the second signal and the third signal, and MSC of the third signal and the first signal. For example, if the sum of the MSC of the first signal and the second signal, the MSC of the second signal and the third signal, and the MSC of the third signal and the first signal is greater than a specified value, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sound, which is generated for the corresponding time period, as the voice. If the sum thereof is less than the specified value, the processor  140  may determine the sound, which is generated for the corresponding time period, as the noise. 
     According to an embodiment, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may assign different weights to the correlation between the first signal and the second signal, the correlation between the second signal and the third signal, and the correlation between the third signal and the first signal, based on a distance between the first microphone  111  and the second microphone  112 , a distance between the second microphone  112  and the third microphone  113 , and a distance between the third microphone  113  and the first microphone  111 . For example, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may obtain information about a frequency of the first signal, the second signal, and/or the third signal. The processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may assign a high weight to a correlation between signals, which are obtained by two microphones having a distance suitable to classify the sound having the corresponding frequency into the voice or the noise. For example, in the case where a high-frequency signal is obtained, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may assign a high weight to a correlation between signals obtained by two microphones, which are adjacent to each other, from among the first microphone  111 , the second microphone  112 , and the third microphone  113 . As another example, in the case where a low-frequency signal is obtained, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may assign a high weight to a correlation between signals obtained by two microphones, which are far from each other, from among the first microphone  111 , the second microphone  112 , and the third microphone  113 . 
     For example, after respectively multiplying different weights and the MSC of the first signal and the second signal, the MSC of the second signal and the third signal, and the MSC of the third signal and the first signal, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sum of pieces of multiplied MSC. The weight may be ‘0’. The processor  140  may determine the sound, which is generated for a specific time period, as the voice or the noise based on the sum thereof to which the weight is applied. 
     According to an embodiment, if the value that is associated with at least one or more of energy of the first signal, energy of the second signal, spectral variance of the first signal, or spectral variance of the second signal is greater than the specified value, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sound, which is generated for a specific time period, as the voice. For example, if the value associated with the difference between the energy of the first signal and the energy of the second signal is greater than the specified value, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may determine the sound, which is generated for a specific time period, as the voice. As another example, if the value associated with at least one of the spectral variance of the first signal or the spectral variance of the second signal is greater than the specified value, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) determine the sound, which is generated for a specific time period, as the voice. Below, the operation of determining the sound as the voice by using the energy and the spectral variance of the first signal and the second signal will be described with reference to  FIG. 4  in greater detail below. 
     According to various embodiments, after determining the sound as the voice or the noise, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may store information indicating the voice or the noise in the memory  120  (e.g., the memory  830  or the memory  930  illustrated in  FIGS. 8 and 9 , respectively) together with a signal corresponding to the sound. The stored information may be used to remove the noise of the transmission signal, to remove the received echo, or to strengthen the received voice. For example, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may amplify a signal in an interval in which the signal is determined as the voice, and may attenuate a signal in an interval in which the signal is determined as the noise. The processor  140  may use, for example, information stored at a point in time when a voice activity detection (VAD) scheme is applied thereto. After removing the noise of the transmission signal, removing the received echo, or strengthening the received voice, the processor  140  (e.g., the processor  820  or the processor  910 ) may send the signal to the external device  200  by using the communication circuit  130 . After removing the noise of the transmission signal, removing the received echo, or strengthening the received voice, the processor  140  (e.g., the processor  820  or the processor  910  illustrated in  FIGS. 8 and 9 , respectively) may perform voice recognition and may send a command corresponding to the voice recognition result to the external device  200 . 
     The external device  200  may receive a signal or a command from the electronic device  100 . The external device  200  may output the signal received from the electronic device  100 . The external device  200  may perform a function corresponding to the command received from the electronic device  100 . 
       FIG. 3  is a flowchart illustrating an example voice and noise classification method of an electronic device, according to an example embodiment of the present disclosure. 
     The flowchart illustrated in  FIG. 3  may include operations which the electronic device  100  illustrated in  FIGS. 1 and 2  processes. Therefore, even though omitted below, the above description about the electronic device  100  may be applied to the flowchart shown in  FIG. 3  with reference to  FIGS. 1 and 2 . 
     Referring to  FIG. 3 , in operation  310 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may obtain a first signal and a second signal. For example, the electronic device  100  may detect a sound, which is generated for a specific time period, by using the first microphone  111  and the second microphone  112 . The electronic device  100  may convert the sound, which is detected by the first microphone  111  and the second microphone  112 , into a discrete signal and may convert the discrete signal into a frequency signal. The first signal may be a frequency signal corresponding to the sound detected by the first microphone  111 , and the second signal may be a frequency signal corresponding to the sound detected by the second microphone  112 . For example, the electronic device  100  may obtain the first signal and the second signal of about 20 msec to about 30 msec, which includes one frame. 
     In operation  320 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may calculate (determine) the MSC of the first signal and the MSC of the second signal. For example, the electronic device  100  may calculate power spectrum (or an autocorrelation function) of the first signal and power spectrum (or an autocorrelation function) of the second signal. The electronic device  100  may calculate cross power spectrum (or a correlation function) between the first signal and the second signal. The electronic device  100  may calculate the MSC by dividing a square of the cross power spectrum by the result obtained by multiplying the power spectrum of the first signal and the power spectrum of the second signal together. The electronic device  100  may calculate the MSC by using a signal, of which a frame is earlier than a frame of the first signal and the second signal, together with the first signal and the second signal. 
     An example Equation for calculating the MSC is as follows: 
     
       
         
           
             
               
                 
                   
                     MSC 
                     ⁡ 
                     
                       ( 
                       f 
                       ) 
                     
                   
                   = 
                   
                     
                       
                          
                         
                           
                             S 
                             xy 
                           
                           ⁡ 
                           
                             ( 
                             f 
                             ) 
                           
                         
                          
                       
                       2 
                     
                     
                       
                         
                           S 
                           xx 
                         
                         ⁡ 
                         
                           ( 
                           f 
                           ) 
                         
                       
                       ⁢ 
                       
                         
                           S 
                           yy 
                         
                         ⁡ 
                         
                           ( 
                           f 
                           ) 
                         
                       
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     Hereinafter, S xx  may be the power spectrum of the first signal. S yy  may be the power spectrum of the second signal. S xy  may be the cross power spectrum of the first signal and the second signal. ‘f’ may be a frequency. 
     
       
         
           
             
               
                 
                   
                     
                       
                         S 
                         xx 
                       
                       ⁡ 
                       
                         ( 
                         f 
                         ) 
                       
                     
                     ≈ 
                     
                       
                         ∑ 
                         n 
                         
                             
                         
                       
                       ⁢ 
                       
                         
                           
                             X 
                             n 
                           
                           ⁡ 
                           
                             ( 
                             f 
                             ) 
                           
                         
                         ⁢ 
                         
                           
                             X 
                             n 
                             * 
                           
                           ⁡ 
                           
                             ( 
                             f 
                             ) 
                           
                         
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       
                         S 
                         yy 
                       
                       ⁡ 
                       
                         ( 
                         f 
                         ) 
                       
                     
                     ≈ 
                     
                       
                         ∑ 
                         n 
                         
                             
                         
                       
                       ⁢ 
                       
                         
                           
                             Y 
                             n 
                           
                           ⁡ 
                           
                             ( 
                             f 
                             ) 
                           
                         
                         ⁢ 
                         
                           
                             Y 
                             n 
                             * 
                           
                           ⁡ 
                           
                             ( 
                             f 
                             ) 
                           
                         
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       
                         S 
                         xy 
                       
                       ⁡ 
                       
                         ( 
                         f 
                         ) 
                       
                     
                     ≈ 
                     
                       
                         ∑ 
                         n 
                         
                             
                         
                       
                       ⁢ 
                       
                         
                           
                             X 
                             n 
                           
                           ⁡ 
                           
                             ( 
                             f 
                             ) 
                           
                         
                         ⁢ 
                         
                           
                             Y 
                             n 
                             * 
                           
                           ⁡ 
                           
                             ( 
                             f 
                             ) 
                           
                         
                       
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     2 
                   
                   ] 
                 
               
             
           
         
       
     
     Hereinafter, X n  may be the first signal. Y n  may be the second signal. ‘n’ may be a frame number. 
     In operation  330 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may compare the MSC with a specified value. For example, the electronic device  100  may determine whether the MSC is greater than the specified threshold value Mth. In the case where a voice is input to the first microphone  111  and the second microphone  112 , frequency characteristics of the first signal and the second signal may be similar to each other because the voice is generated a user. Accordingly, in a frame in which the voice is included, the magnitude of S xy  being a correlation function of the first signal and the second signal may be great. On the other hand, in the case where a noise is input to the first microphone  111  and the second microphone  112 , frequency characteristics of the first signal and the second signal may be different from each other because the noise is generated from a specific direction. Accordingly, in a frame in which only the noise is included, the magnitude of S xy  being the correlation function of the first signal and the second signal may be small. The magnitude of MSC may be proportional to the magnitude of S xy . 
     In the case where the MSC is greater than the specified value, in operation  340 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may determine the signal as the voice. As described above, in the case where the voice is included in the first signal and the second signal, the magnitude of the MSC may be greater than the specified value. Accordingly, the electronic device  100  may recognize the signal, which corresponds to a frame in which the MSC is greater than the specified value, as the voice. 
     In the case where the MSC is less than the specified value, in operation  350 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may determine the signal as the noise. As described above, in the case where the voice is not included in the first signal and the second signal, the magnitude of the MSC may be less than the specified value. Accordingly, the electronic device  100  may recognize the signal, which corresponds to a frame in which the MSC is less than the specified value, as the noise. 
     As described above, in the case where the sound is received by using a plurality of microphones disposed at locations, which are spaced apart from each other, a frame in which a voice is included and a frame in which the voice is not included may indicate different characteristics due to a spatial characteristic of the sound, in which the voice is generated at a specific location and the noise is generated from a specific direction. In the case of the frame in which the voice is included, it is indicated that a correlation between the first signal and the second signal is high. In the case of the frame in which the voice is not included, it is indicated that the correlation between the first signal and the second signal is low. The accuracy to distinguish between the voice and the noise may be improved by using the above-mentioned correlation. In addition, even though a distance between a user and the electronic device  100  is far, the above-mentioned characteristic is maintained. Accordingly, the electronic device  100 , such as a home smart device, or the like, which recognizes the voice generated at a location far from the electronic device  100  may accurately distinguish between a voice and a noise. 
       FIG. 4  is a flowchart illustrating an example voice and noise classification method of an electronic device, according to an example embodiment of the present disclosure. For convenience of description, a detailed description about an operation that is the same as an operation described with reference to  FIG. 3  will not be repeated here. 
     The flowchart illustrated in  FIG. 4  may include operations which the electronic device  100  illustrated in  FIGS. 1 and 2  processes. Therefore, even though omitted below, the above description about the electronic device  100  may be applied to the flowchart shown in  FIG. 4  with reference to  FIGS. 1 and 2 . 
     Referring to  FIG. 4 , in operation  410 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may obtain a first signal and a second signal. 
     In operation  420 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may calculate energy and spectral variance of each of the first signal and the second signal. For example, the electronic device  100  may calculate energy E 1  of the first signal based on a square of a magnitude of the first signal, and the electronic device  100  may calculate energy E 2  of the second signal based on a square of a magnitude of the second signal. The electronic device  100  may calculate spectral variance V 1  of the first signal based on frequency distribution of the first signal, and the electronic device  100  may calculate spectral variance V 2  of the second signal based on frequency distribution of the second signal. 
     In operation  430 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may compare at least a portion of energy and spectral variance of each of the first signal and the second signal with a specified value. 
     According to an embodiment, the electronic device  100  may determine whether a difference |E 1 −E 2 | between the energy of the first signal and the energy of the second signal is greater than a specified threshold value Eth. For example, since the voice of a user of the electronic device  100  is generated at a location that is adjacent to the electronic device  100 , the user voice may be propagated toward a specific location, and in particular, the user voice may be propagated toward the first microphone  111 . Accordingly, in the case where a voice is included in the first signal and the second signal, an energy difference between the first signal, which is obtained by the first microphone  111  adjacent to a location at which the voice is generated, and the second signal obtained by the second microphone  112  that is far from a location in which the voice is generated may be great. Accordingly, in operation  460 , the electronic device  100  may determine a signal, in which the energy difference is greater than the specified value, as a voice. As another example, since the noise is generated at a location far from the electronic device  100  and is distributed or scattered in a specific direction, in the case where the voice is not included in the first signal and the second signal, the energy difference between the first signal and the second signal may be small. Accordingly, the electronic device  100  may perform operation  440  and operation  450  on a signal in which the energy difference is less than the specified value and may determine a sound as a voice or a noise. 
     According to an embodiment, the electronic device  100  may determine whether spectral variance V 1  of the first signal or spectral variance V 2  of the second signal is greater than a specified threshold value Vth. For example, since the voice changes abruptly in process of time, in the case where the voice is included in the first signal or the second signal, spectral variance of the first signal or the second signal may be great. Accordingly, the electronic device  100  may determine a signal, in which the spectral variance of the first signal or the second signal is greater than the specified value, as a voice. As another example, since the degree of change of the noise is smaller than the degree of change of the voice (e.g., a white noise), in the case where the voice is not included in the first signal or the second signal, spectral variance of the first signal or the second signal may be small. Accordingly, the electronic device  100  may determine a signal, in which the spectral variance of the first signal or the second signal is less than the specified value, as the noise. 
     In the case where the energy difference |E 1 −E 2 | between the first signal and the second signal is greater than the specified value Eth and the spectral variance V 1  of the first signal or the spectral variance V 2  of the second signal is greater than the specified value Vth, in operation  460 , the electronic device  100  may determine the signal as the voice. 
     In the case where the signal is not determined as the voice, in operation  440 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may calculate the MSC of the first signal and the second signal. 
     In operation  450 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may determine whether the MSC is greater than the specified threshold value Mth. 
     In the case where the MSC is greater than the specified value Mth, in operation  460 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may determine the signal as the voice. 
     In the case where the MSC is less than the specified value Mth, in operation  470 , the electronic device  100  (e.g., the processor  140 , the processor  820 , or the processor  910 ) may determine the signal as the noise. 
     As described above, firstly, the sound may be classified into the voice by using a value that is calculated by a simple arithmetic operation such as energy, spectral variance, or the like, compared with the MSC. In the case where the sound is not classified as the voice, secondarily, the sound may be classified as a voice and a noise by using the MSC, thereby reducing processing time for distinguishing between the voice and the noise. In addition, according to an embodiment, since the electronic device  100  may perform additional classification by using the MSC, threshold values such as Eth, Vth, and the like may be set to be higher than that of a conventional electronic device, thereby reducing a false recognition rate at which the noise is determined as the voice. 
       FIGS. 5A and 5B  are graphs illustrating an example comparison result in which a voice and a noise is recognized by an electronic device, according to an example embodiment of the present disclosure. 
     According to a method described with reference to  FIG. 4 , the embodiment-related experiment result may indicate the result of distinguishing between a noise and a voice based on MSC. A comparison example-related experiment result may indicate the result of distinguishing between a noise and a voice based on energy and spectral variance of a sound received by one microphone. In  FIGS. 5A and 5B , a time period surrounded in a box may indicate a time period in which the sound is recognized as the voice, and the remaining time period may indicate a time period in which the sound is recognized as the noise. 
     Referring to  FIG. 5A , in the case where a voice and a noise are distinguished based on the comparison example, it may be determined that a voice interval in which the voice is included mostly includes the voice. However, in the case of an interval, such as interval ‘a’, interval ‘b’, and interval ‘c’, in which a magnitude of the noise is great or in which the change in the width of the noise is great with time, even though the voice is not included in the interval, it may be determined that the voice is included in the interval. Accordingly, since a signal of a noise interval in which the voice is not included is amplified and the noise is not removed, call quality or voice recognition quality may be reduced. 
     Referring to  FIG. 5B , in the case where the voice and the noise are distinguished by using the electronic device according to an embodiment, it may be determined that a voice interval in which the voice is included nearly includes the voice. Furthermore, in spite of an interval, such as interval ‘a’, interval ‘b’, and interval ‘c’, in which a magnitude of the noise is great or in which the change magnitude of the noise is great with time, the electronic device according to an embodiment may determine the corresponding interval as the noise. According to an embodiment, since the electronic device uses correlations of sounds received by a plurality of microphones, the electronic device may distinguish a noise regardless of the magnitude or the change in the width of the noise. A signal of a voice interval is amplified or the noise interval is removed because the voice and the noise are distinguished, thereby improving call quality or voice recognition quality. 
       FIGS. 6A and 6B  are graphs illustrating an example comparison result in which a signal is processed by an electronic device, according to an example embodiment of the present disclosure. 
     According to a method described with reference to  FIG. 4 , the experiment result according to an embodiment may indicate an output signal strengthened by a voice activity detection (VAD) scheme after a noise and a voice are distinguished based on MSC. An experiment result based on a comparison example may indicate an output signal strengthened by the VAD scheme after the noise and the voice are distinguished based on energy and spectral variance of a sound received by one microphone. 
     Referring to  FIG. 6A , after the voice and the noise are distinguished based on the comparison example, an interval in which the sound is determined as the voice may be strengthened. For example, signals included in interval ‘d’, interval ‘e’, and interval ‘f’ may be amplified. A part of an interval including the signal amplified according to the comparison example may be an interval in which a voice is not included. For example, interval ‘f’ may be an interval in which the voice is not included. Accordingly, in the case where a signal of an interval in which the voice is not included is amplified, call quality or voice recognition quality may be reduced. 
     Referring to  FIG. 6B , after distinguishing between the voice and the noise, the electronic device according to an embodiment may strengthen an interval in which the sound is recognized as the voice. For example, the electronic device may amplify signals of interval ‘d’ and interval ‘e’. Unlike the comparison example, the electronic device according to an embodiment may determine a signal of interval ‘e’ as the noise and may not amplify a signal of interval ‘e’. In the case where the voice and the noise are distinguished by the electronic device, accuracy of the distinction may be improved. Therefore, when the signal is amplified, a gain may be set to be higher than that of the comparison example. The quality of an output signal may be improved because the accuracy of distinguishing between the voice and the noise is improved and the gain of amplifying the voice is set to be high. 
       FIGS. 7A and 7B  are tables illustrating example sound quality comparison results of a signal processed by an electronic device, according to an example embodiment of the present disclosure. 
     A sound quality evaluation index illustrated in  FIGS. 7A and 7B  may be calculated according to a perceptual evaluation of speech quality (PESQ) evaluation method being an International Telecommunication Union (ITU) standard. The sound quality evaluation index of a signal processed according to an embodiment may indicate the sound quality evaluation index of the output signal strengthened by a VAD scheme after the noise and the voice are distinguished based on the method described with reference to  FIG. 4 . The sound quality evaluation index of a signal processed according to the comparison example may indicate the sound quality evaluation index of the output signal strengthened by a VAD scheme after the noise and the voice are distinguished based on energy and spectral variance of a sound received by one microphone. 
     Referring to  FIG. 7A , with regard to a broadband signal and a narrowband signal, the sound quality evaluation index of each of an embodiment-related output signal and a comparison example-related output signal may be calculated in a clean environment, in which the noise is not included, and a noise environment in which a stationary noise is included. Since the embodiment-related output signal obtains a score, which is higher than the comparison example-related output signal, in the clean environment, it may be seen that the electronic device according to an embodiment is operated without a malfunction. In the noise environment, with regard to the narrowband signal and the broadband signal, the embodiment-related output signal obtains a score, which is higher than the comparison example-related output signal by 0.12 and 0.09, respectively. Accordingly, it may be seen that the quality of an output signal will be improved in an environment in which a stationary noise is included by an electronic device according to an embodiment. 
     Referring to  FIG. 7B , with regard to the broadband signal and the narrowband signal, the sound quality evaluation index of the embodiment-related output signal and the comparison example-related output signal may be calculated in a Mensa environment, a Xroad environment, and a Road environment in which a non-stationary noise is included. In the Mensa environment, with regard to the narrowband signal and the broadband signal, the embodiment-related output signal obtains a score that is higher than the comparison example-related output signal by 0.14 and 0.13, respectively. In the Xroad environment, with regard to the narrowband signal and the broadband signal, the embodiment-related output signal obtains a score that is higher than the comparison example-related output signal by 0.29 and 0.23, respectively. In the Road environment, with regard to the narrowband signal and the broadband signal, the embodiment-related output signal obtains a score that is higher than the comparison example-related output signal by 0.25 and 0.22, respectively. As described above, it may be seen that the quality of the output signal will be improved in an environment in which the non-stationary noise is included by the electronic device according to an embodiment. In addition, it may be seen that the sound quality is improved at a point in time when the non-stationary noise is included as compared with the case in which a stationary noise is included. 
       FIG. 8  is a diagram illustrating an example electronic device in a network environment, according to various example embodiments of the present disclosure. 
     Referring to  FIG. 8 , according to various embodiments, an electronic device  801 ,  802 , or  804  or a server  806  may be connected with each other through a network  862  or a local area (or short-range wireless) network  864 . The electronic device  801  may include a bus  810 , a processor (e.g., including processing circuitry)  820 , a memory  830 , an input/output (I/O) interface (e.g., including input/output circuitry)  850 , a display  860 , and a communication interface (e.g., including communication circuitry)  870 . According to an embodiment, the electronic device  801  may not include at least one of the above-described elements or may further include other element(s). 
     The bus  810  may interconnect the above-described elements  810  to  870  and may be a circuit for conveying communications (e.g., a control message and/or data) among the above-described elements. 
     The processor  820  may include various processing circuitry, such as, for example, and without limitation, one or more of a dedicated processor, a central processing unit (CPU), an application processor (AP), or a communication processor (CP). The processor  820  may perform, for example, data processing or an operation associated with control or communication of at least one other element(s) of the electronic device  801 . 
     The memory  830  may include a volatile and/or nonvolatile memory. For example, the memory  830  may store instructions or data associated with at least one other element(s) of the electronic device  801 . According to an embodiment, the memory  830  may store software and/or a program  840 . The program  840  may include, for example, a kernel  841 , a middleware  843 , an application programming interface (API)  845 , and/or an application program (or “application”)  847 . At least a part of the kernel  841 , the middleware  843 , or the API  845  may be called an “operating system (OS)”. 
     The kernel  841  may control or manage system resources (e.g., the bus  810 , the processor  820 , the memory  830 , and the like) that are used to execute operations or functions of other programs (e.g., the middleware  843 , the API  845 , and the application program  847 ). Furthermore, the kernel  841  may provide an interface that allows the middleware  843 , the API  845 , or the application program  847  to access discrete elements of the electronic device  801  so as to control or manage system resources. 
     The middleware  843  may perform, for example, a mediation role such that the API  845  or the application program  847  communicates with the kernel  841  to exchange data. 
     Furthermore, the middleware  843  may process one or more task requests received from the application program  847  according to a priority. For example, the middleware  843  may assign the priority, which makes it possible to use a system resource (e.g., the bus  810 , the processor  820 , the memory  830 , or the like) of the electronic device  801 , to at least one of the application program  847 . For example, the middleware  843  may process the one or more task requests according to the priority assigned to the at least one, which makes it possible to perform scheduling or load balancing on the one or more task requests. 
     The API  845  may be an interface through which the application program  847  controls a function provided by the kernel  841  or the middleware  843 , and may include, for example, at least one interface or function (e.g., an instruction) for a file control, a window control, image processing, a character control, or the like. 
     The I/O interface  850  may include various I/O circuitry configured to transmit an instruction or data, input from a user or another external device, to other element(s) of the electronic device  801 . Furthermore, the I/O interface  850  may output an instruction or data, received from other component(s) of the electronic device  801 , to a user or another external device. 
     The display  860  may include, for example, a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, a microelectromechanical systems (MEMS) display, or an electronic paper display, or the like, but is not limited thereto. The display  860  may display, for example, various kinds of contents (e.g., a text, an image, a video, an icon, a symbol, or the like) to a user. The display  860  may include a touch screen and may receive, for example, a touch, gesture, proximity, or hovering input using an electronic pen or a portion of a user&#39;s body. 
     The communication interface  870  may include various communication circuitry and may establish communication between the electronic device  801  and an external device (e.g., the first external electronic device  802 , the second external electronic device  804 , or the server  806 ). For example, the communication interface  870  may be connected to the network  862  through wireless communication or wired communication to communicate with the external device (e.g., the second external electronic device  804  or the server  806 ). 
     The wireless communication may include at least one of, for example, a long-term evolution (LTE), an LTE Advance (LTE-A), a code division multiple access (CDMA), a wideband CDMA (WCDMA), a universal mobile telecommunications system (UNITS), a wireless broadband (WiBro), a global system for mobile communications (GSM), or the like, as a cellular communication protocol. Furthermore, the wireless communication may include, for example, the local area or short-range wireless network  864 . The local area network  864  may include at least one of a wireless fidelity (Wi-Fi), a Bluetooth, a near field communication (NFC), a magnetic stripe transmission (MST), a global navigation satellite system (GNSS), or the like. 
     The MST may generate a pulse in response to transmission data by using an electromagnetic signal, and the pulse may generate a magnetic field signal. The electronic device  801  may send the magnetic field signal to point of sale (POS). The POS may detect the magnetic field signal using a MST reader and may recover the data by converting the detected magnetic field signal to an electrical signal. 
     According to an embodiment, a wireless communication may include the GNSS. The GNSS may include at least one of a global positioning system (GPS), a global navigation satellite system (Glonass), a Beidou Navigation Satellite System (hereinafter referred to as “Beidou”), or an European global satellite-based navigation system (Galileo). In this specification, “GPS” and “GNSS” may be interchangeably used. The wired communication may include at least one of, for example, a universal serial bus (USB), a high definition multimedia interface (HDMI), a recommended standard-232 (RS-232), a plain old telephone service (POTS), or the like. The network  862  may include at least one of telecommunications networks, for example, a computer network (e.g., LAN or WAN), an Internet, or a telephone network. 
     Each of the first and second external electronic devices  802  and  804  may be a device of which the type is different from or the same as that of the electronic device  801 . According to an embodiment, the server  806  may include a server or a group of two or more servers. According to various embodiments, all or a part of operations that the electronic device  801  will perform may be executed by another or plural electronic devices (e.g., the electronic device  802  or  804  or the server  806 ). According to an embodiment, in the case where the electronic device  801  executes any function or service automatically or in response to a request, the electronic device  801  may not perform the function or the service internally, but, alternatively additionally, it may request at least a portion of a function associated with the electronic device  101  from other devices (e.g., the electronic device  802  or  804  or the server  806 ). The other electronic device (e.g., the electronic device  802  or  804  or the server  806 ) may execute the requested function or additional function and may transmit the execution result to the electronic device  801 . The electronic device  801  may provide the requested function or service by processing the received result as it is, or additionally. To this end, for example, cloud computing, distributed computing, or client-server computing may be used. 
       FIG. 9  is a block diagram illustrating an example electronic device, according to an example embodiment of the present disclosure. 
     Referring to  FIG. 9 , the electronic device  901  may include, for example, all or a part of the electronic device  801  illustrated in  FIG. 8 . The electronic device  901  may include one or more processors (e.g., including processing circuitry)  910  (e.g., the processor  140 ), a communication module (e.g., including communication circuitry)  920 , a subscriber identification module  929 , a memory  930  (e.g., the memory  120 ), a security module  936 , a sensor module  940 , an input device (e.g., including input circuitry)  950 , a display  960 , an interface (e.g., including interface circuitry)  970 , an audio module  980 , a camera module  991 , a power management module  995 , a battery  996 , an indicator  997 , and a motor  998 . 
     The processor  910  may include various processing circuitry and drive an operating system (OS) or an application program to control a plurality of hardware or software elements connected to the processor  910  and may process and compute a variety of data. The processor  910  may be implemented with a System on Chip (SoC), for example. According to an embodiment of the present disclosure, the AP  910  may further include a graphic processing unit (GPU) and/or an image signal processor. The processor  910  may include at least a part (e.g., a cellular module  921 ) of elements illustrated in  FIG. 9 . The processor  910  may load and process an instruction or data, which is received from at least one of other components (e.g., a nonvolatile memory), and may store a variety of data in a nonvolatile memory. 
     The communication module  920  may be configured the same as or similar to a communication interface  870  of  FIG. 8 . The communication module  920  may include various communication circuitry, such as, for example, and without limitation, a cellular module  921 , a Wi-Fi module  922 , a Bluetooth (BT) module  923 , a GNSS module  924  (e.g., a GPS module, a Glonass module, a Beidou module, or a Galileo module), a near field communication (NFC) module  925 , a MST module  926 , and a radio frequency (RF) module  927 . 
     The cellular module  921  may provide voice communication, video communication, a character service, an Internet service, or the like through a communication network. According to an embodiment, the cellular module  921  may perform discrimination and authentication of the electronic device  901  within a communication network using the subscriber identification module  929  (e.g., a SIM card). According to an embodiment, the cellular module  921  may perform at least a portion of functions that the processor  910  provides. According to an embodiment, the cellular module  921  may include a communication processor (CP). 
     Each of the Wi-Fi module  922 , the BT module  923 , the GNSS module  924 , the NFC module  925 , or the MST module  926  may include a processor for processing data exchanged through a corresponding module, for example. According to an embodiment, at least a part (e.g., two or more elements) of the cellular module  921 , the Wi-Fi module  922 , the BT module  923 , the GNSS module  924 , the NFC module  925 , or the MST module  926  may be included within one integrated circuit (IC) or an IC package. 
     The RF module  927  may transmit and receive, for example, a communication signal (e.g., an RF signal). For example, the RF module  927  may include a transceiver, a power amplifier module (PAM), a frequency filter, a low noise amplifier (LNA), an antenna, or the like. According to another embodiment, at least one of the cellular module  921 , the Wi-Fi module  922 , the BT module  923 , the GNSS module  924 , the NFC module  925 , or the MST module  926  may transmit and receive an RF signal through a separate RF module. 
     The subscriber identification module  929  may include, for example, a card and/or embedded SIM which includes a subscriber identification module and may include unique identification information (e.g., integrated circuit card identifier (ICCID)) or subscriber information (e.g., integrated mobile subscriber identity (IMSI)). 
     For example, the memory  930  (e.g., the memory  830 ) may include an internal memory  932  and/or an external memory  934 . For example, the internal memory  932  may include at least one of a volatile memory (e.g., a dynamic random access memory (DRAM), a static RAM (SRAM), or a synchronous DRAM (SDRAM)), a nonvolatile memory (e.g., a one-time programmable read only memory (OTPROM), a programmable ROM (PROM), an erasable and programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a mask ROM, a flash ROM, a flash memory (e.g., a NAND flash, a NOR flash, or the like)), a hard drive, or a solid state drive (SSD). 
     The external memory  934  may further include a flash drive such as compact flash (CF), secure digital (SD), micro secure digital (Micro-SD), mini secure digital (Mini-SD), extreme digital (xD), a multimedia card (MMC), a memory stick, or the like. The external memory  934  may be functionally and/or physically connected with the electronic device  901  through various interfaces. 
     The security module  936  may be a module that includes a storage space of which a security level is higher than that of the memory  930  and may include a circuit that guarantees safe data storage and a protected execution environment. The security module  936  may be implemented with a separate circuit and may include a separate processor. For example, the security module  936  may be in a smart chip or a secure digital (SD) card, which is removable, or may include an embedded secure element (eSE) embedded in a fixed chip of the electronic device  901 . Furthermore, the security module  936  may operate based on an operating system (OS) that is different from the OS of the electronic device  901 . For example, the security module  936  may operate based on java card open platform (JCOP) OS. 
     The sensor module  940  may measure, for example, a physical quantity or may detect an operating state of the electronic device  901 . The sensor module  940  may convert the measured or detected information to an electric signal. For example, the sensor module  940  may include at least one of a gesture sensor  940 A, a gyro sensor  940 B, a barometric pressure sensor  940 C, a magnetic sensor  940 D, an acceleration sensor  940 E, a grip sensor  940 F, a proximity sensor  940 G, a color sensor  940 H (e.g., a red, green, blue (RGB) sensor), a biometric sensor  940 I, a temperature/humidity sensor  940 J, an illuminance (e.g., illumination) sensor  940 K, or an UV sensor  940 M. Although not illustrated, additionally or generally, the sensor module  940  may further include, for example, an E-nose sensor, an electromyography sensor (EMG) sensor, an electroencephalogram (EEG) sensor, an electrocardiogram (ECG) sensor, an infrared (IR) sensor, an iris sensor, and/or a fingerprint sensor. The sensor module  940  may further include a control circuit for controlling at least one or more sensors included therein. According to an embodiment, the electronic device  901  may further include a processor which is a part of the processor  910  or independent of the processor  910  and is configured to control the sensor module  940 . The processor may control the sensor module  940  while the processor  910  remains at a sleep state. 
     The input device  950  may include various input circuitry, such as, for example, and without limitation, a touch panel  952 , a (digital) pen sensor  954 , a key  956 , or an ultrasonic input device  958 . The touch panel  952  may use at least one of capacitive, resistive, infrared and ultrasonic detecting methods. Also, the touch panel  952  may further include a control circuit. The touch panel  952  may further include a tactile layer to provide a tactile reaction to a user. 
     The (digital) pen sensor  954  may be, for example, a part of a touch panel or may include an additional sheet for recognition. The key  956  may include, for example, a physical button, an optical key, a keypad, and the like. The ultrasonic input device  958  may detect (or sense) an ultrasonic signal, which is generated from an input device, through a microphone (e.g., a microphone  988 ) and may verify data corresponding to the detected ultrasonic signal. 
     The display  960  (e.g., the display  860 ) may include a panel  962 , a hologram device  964 , or a projector  966 . The panel  962  may be configured the same as or similar to the display  860  of  FIG. 8 . The panel  962  may be implemented to be flexible, transparent or wearable, for example. The panel  962  and the touch panel  952  may be integrated into a single module. The hologram device  964  may display a stereoscopic image in a space using a light interference phenomenon. The projector  966  may project light onto a screen so as to display an image. The screen may be arranged inside or outside the electronic device  901 . According to an embodiment, the display  960  may further include a control circuit for controlling the panel  962 , the hologram device  964 , or the projector  966 . 
     The interface  970  may include various interface circuitry, such as, for example, and without limitation, a high-definition multimedia interface (HDMI)  972 , a universal serial bus (USB)  974 , an optical interface  976 , or a D-subminiature (D-sub)  978 . The interface  970  may be included, for example, in the communication interface  870  illustrated in  FIG. 8 . Additionally or generally, the interface  970  may include, for example, a mobile high definition link (MHL) interface, a SD card/multimedia card (MMC) interface, or an infrared data association (IrDA) standard interface. 
     The audio module  980  may convert a sound and an electric signal in dual directions. At least a part of the audio module  980  may be included, for example, in the I/O interface  850  illustrated in  FIG. 8 . The audio module  980  may process, for example, sound information that is input or output through a speaker  982 , a receiver  984 , an earphone  986 , or a microphone  113  (e.g., the first microphone  111 , the second microphone  112 , and the third microphone  113 ). 
     The camera module  991  for shooting a still image or a video may include, for example, at least one image sensor (e.g., a front sensor or a rear sensor), a lens, an image signal processor (ISP), or a flash (e.g., an LED or a xenon lamp). 
     The power management module  995  may manage, for example, power of the electronic device  901 . According to an embodiment, the power management module  995  may include a power management integrated circuit (PMIC), a charger IC, or a battery or fuel gauge. The PMIC may have a wired charging method and/or a wireless charging method. The wireless charging method may include, for example, a magnetic resonance method, a magnetic induction method, or an electromagnetic method and may further include an additional circuit, for example, a coil loop, a resonant circuit, a rectifier, or the like. The battery gauge may measure, for example, a remaining capacity of the battery  996  and a voltage, current or temperature thereof while the battery is charged. The battery  996  may include, for example, a rechargeable battery and/or a solar battery. 
     The indicator  997  may display a specific state of the electronic device  901  or a part thereof (e.g., the processor  910 ), such as a booting state, a message state, a charging state, or the like. The motor  998  may convert an electrical signal into a mechanical vibration and may generate the following effects: vibration, haptic, and the like. Although not illustrated, the electronic device  901  may include a processing device (e.g., a GPU) for supporting a mobile TV. The processing device for supporting a mobile TV may process media data according to the standards of digital multimedia broadcasting (DMB), digital video broadcasting (DVB), MediaFlo™, or the like. 
     Each of the above-mentioned elements of the electronic device in the present disclosure may be configured with one or more components, and the names of the elements may be changed according to the type of the electronic device. According to various embodiments, the electronic device may include at least one of the above-mentioned elements, and some elements may be omitted or other additional elements may be added. Furthermore, some of the elements of the electronic device according to various embodiments may be combined with each other so as to form one entity, so that the functions of the elements may be performed in the same manner as before the combination. 
       FIG. 10  is a block diagram illustrating an example program module, according to various example embodiments of the present disclosure. 
     According to an embodiment, a program module  1010  (e.g., the program  840 ) may include an operating system (OS) to control resources associated with an electronic device (e.g., the electronic device  801 ), and/or diverse applications (e.g., the application program  847 ) driven on the OS. The OS may be, for example, Android™, iOS™, Windows™, Symbian™, Tizen™, Bada™, or the like. 
     The program module  1010  may include a kernel  1020 , a middleware  1030 , an API  1060 , and/or an application  1070 . At least a part of the program module  1010  may be preloaded on an electronic device or may be downloadable from an external electronic device (e.g., the electronic device  802  or  804 , the server  806 , or the like). 
     The kernel  1020  (e.g., the kernel  841 ) may include, for example, a system resource manager  1021 , or a device driver  1023 . The system resource manager  1021  may perform control, allocation, or retrieval of system resources. According to an embodiment, the system resource manager  1021  may include a process managing part, a memory managing part, a file system managing part, or the like. The device driver  1023  may include, for example, a display driver, a camera driver, a Bluetooth driver, a common memory driver, an USB driver, a keypad driver, a Wi-Fi driver, an audio driver, or an inter-process communication (IPC) driver. 
     The middleware  1030  may provide, for example, a function which the application  1070  needs in common or may provide diverse functions to the application  1070  through the API  1060  to allow the application  1070  to efficiently use limited system resources of the electronic device. According to an embodiment, the middleware  1030  (e.g., the middleware  843 ) may include at least one of a runtime library  1035 , an application manager  1041 , a window manager  1042 , a multimedia manager  1043 , a resource manager  1044 , a power manager  1045 , a database manager  1046 , a package manager  1047 , a connectivity manager  1048 , a notification manager  1049 , a location manager  1050 , a graphic manager  1051 , a security manager  1052 , or a payment manager  1054 . 
     The runtime library  1035  may include, for example, a library module, which is used by a compiler, to add a new function through a programming language while the application  1070  is being executed. The runtime library  1035  may perform input/output management, memory management, capacities about arithmetic functions, or the like. 
     The application manager  1041  may manage, for example, a life cycle of at least one application of the application  1070 . The window manager  1042  may manage a GUI resource which is used in a screen. The multimedia manager  1043  may identify a format necessary to play diverse media files, and may perform encoding or decoding of media files by using a codec suitable for the format. The resource manager  1044  may manage resources such as a storage space, memory, or source code of at least one application of the application  1070 . 
     The power manager  1045  may operate, for example, with a basic input/output system (BIOS) to manage a battery or power, and may provide power information for an operation of an electronic device. The database manager  1046  may generate, search for, or modify database to be used in at least one application of the application  1070 . The package manager  1047  may install or update an application which is distributed in the form of a package file. 
     The connectivity manager  1048  may manage, for example, wireless connection such as Wi-Fi or Bluetooth. The notification manager  1049  may display or notify an event such as an arrival message, an appointment, or a proximity notification in a mode that does not disturb a user. The location manager  1050  may manage location information of an electronic device. The graphic manager  1051  may manage a graphic effect to be provided to a user or a user interface relevant thereto. The security manager  1052  may provide a general security function necessary for system security, user authentication, or the like. According to an embodiment, in the case where an electronic device (e.g., the electronic device  801 ) includes a telephony function, the middleware  1030  may further includes a telephony manager for managing a voice or video call function of the electronic device. 
     The middleware  1030  may include a middleware module that combines diverse functions of the above-described elements. The middleware  1030  may provide a module specialized to each OS kind to provide differentiated functions. In addition, the middleware  1030  may remove a part of the preexisting elements, dynamically, or may add new elements thereto. 
     The API  1060  (e.g., the API  845 ) may be, for example, a set of programming functions and may be provided with a configuration which is variable depending on an OS. For example, in the case where an OS is the android or the iOS™, it may be permissible to provide one API set per platform. In the case where an OS is the Tizen™, it may be permissible to provide two or more API sets per platform. 
     The application  1070  (e.g., the application program  847 ) may include, for example, one or more applications capable of providing functions for a home  1071 , a dialer  1072 , an SMS/MMS  1073 , an instant message (IM)  1074 , a browser  1075 , a camera  1076 , an alarm  1077 , a contact  1078 , a voice dial  1079 , an e-mail  1080 , a calendar  1081 , a media player  1082 , an album  1083 , and a clock  1084 , a payment  1085 , or for offering health care (e.g., measuring an exercise quantity or blood sugar) or environment information (e.g., information of barometric pressure, humidity, or temperature). 
     According to an embodiment, the application  1070  may include an application (hereinafter referred to as “information exchanging application” for descriptive convenience) to support information exchange between the electronic device (e.g., the electronic device  801 ) and an external electronic device (e.g., the electronic device  802  or  804 ). The information exchanging application may include, for example, a notification relay application for transmitting specific information to the external electronic device, or a device management application for managing the external electronic device. 
     For example, the information exchanging application may include a function of transmitting notification information, which arise from other applications (e.g., applications for SMS/MMS, e-mail, health care, or environmental information), to an external electronic device (e.g., an electronic device  802  or  804 ). Additionally, the information exchanging application may receive, for example, notification information from an external electronic device and provide the notification information to a user. 
     The device management application may manage (e.g., install, delete, or update), for example, at least one function (e.g., turn-on/turn-off of an external electronic device itself (or a part of components) or adjustment of brightness (or resolution) of a display) of the external electronic device (e.g., the electronic device  802  or  804 ) which communicates with the electronic device, an application running in the external electronic device, or a service (e.g., a call service, a message service, or the like) provided from the external electronic device. 
     According to an embodiment, the application  1070  may include an application (e.g., a health care application of a mobile medical device, and the like) which is assigned in accordance with an attribute of the external electronic device (e.g., the electronic device  802  or  804 ). According to an embodiment, the application  1070  may include an application which is received from an external electronic device (e.g., the server  806  or the electronic device  802  or  804 ). According to an embodiment, the application  1070  may include a preloaded application or a third party application which is downloadable from a server. The component titles of the program module  1010  according to the embodiment may be modifiable depending on kinds of operating systems. 
     According to various embodiments, at least a part of the program module  1010  may be implemented by software, firmware, hardware, or a combination of two or more thereof. At least a part of the program module  1010  may be implemented (e.g., executed), for example, by a processor (e.g., the processor  910 ). At least a portion of the program module  1010  may include, for example, a module, a program, a routine, sets of instructions, or a process for performing one or more functions. 
     The term “module” used herein may refer, for example, to a unit including one or more combinations of hardware, software and firmware. The term “module” may be interchangeably used with the terms “unit”, “logic”, “logical block”, “component” and “circuit”. The “module” may be a minimum unit of an integrated component or may be a part thereof. The “module” may be a minimum unit for performing one or more functions or a part thereof. The “module” may be implemented mechanically or electronically. For example, the “module” may include at least one of a dedicated processor, a CPU, an application-specific IC (ASIC) chip, a field-programmable gate array (FPGA), and a programmable-logic device for performing some operations, which are known or will be developed. 
     At least a portion of an apparatus (e.g., modules or functions thereof) or a method (e.g., operations) according to various embodiments of the present disclosure may be, for example, implemented by instructions stored in a computer-readable storage media in the form of a program module. The instruction, when executed by a processor (e.g., the processor  820 ), may cause the one or more processors to perform a function corresponding to the instruction. According to an embodiment, a computer recording medium storing an instruction that is executed by at least one processor and is readable by a computer, the instruction, when executed by the processor, causing the computer to change a sound, which is obtained from the first microphone for a specific time period, into a first signal, to change a sound, which is obtained from the second microphone arranged at a location spaced apart from the first microphone, into a second signal, and to recognize the sound, which is generated for the time period, as a voice or a noise based on a frequency-related correlation between the first signal and the second signal. The computer-readable storage media, for example, may be the memory  830 . 
     A computer-readable recording medium may include a hard disk, a magnetic media, a floppy disk, a magnetic media (e.g., a magnetic tape), an optical media (e.g., a compact disc read only memory (CD-ROM) and a digital versatile disc (DVD), a magneto-optical media (e.g., a floptical disk), and hardware devices (e.g., a read only memory (ROM), a random access memory (RAM), or a flash memory). Also, a program instruction may include not only a mechanical code such as things generated by a compiler but also a high-level language code executable on a computer using an interpreter. The above hardware unit may be configured to operate as one or more software modules to perform an operation according to various embodiments, and vice versa. 
     Modules or program modules according to various embodiments may include at least one or more of the above-mentioned elements, some of the above-mentioned elements may be omitted, or other additional elements may be further included therein. Operations executed by modules, program modules, or other elements according to various embodiments may be executed by a successive method, a parallel method, a repeated method, or a heuristic method. In addition, a part of operations may be executed in different sequences or may be omitted. Alternatively, other operations may be added. 
     According to various embodiments of the present disclosure, the accuracy for determining a noise interval may be improved by distinguishing between a voice interval and a noise interval based on a correlation between two or more signals obtained by two or more microphones. 
     Besides, a variety of effects directly or indirectly understood through this disclosure may be provided. 
     While the present disclosure has been illustrated and described with reference to various example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.