Patent Publication Number: US-2021168503-A1

Title: Active noise reduction audio devices and systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of and claims priority to U.S. patent application Ser. No. 16/565,293 filed Sep. 9, 2019, and titled “Active Noise Reduction Audio Devices and Systems,” which application is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure generally relates to methods and systems directed to controlling audio devices, such as headphones, with active noise reduction. 
     SUMMARY 
     All examples and features mentioned below can be combined in any technically possible way. 
     Generally, in one aspect, a method of controlling an Active Noise Reduction (ANR) audio system is provided. The method comprises: generating one or more control signals, using a controller, to set one or more ANR parameters of a first and a second wearable audio device to a first ANR state; detecting at least one of: whether the first wearable audio device is engaged with or removed from a first ear of a user, using a first sensor of the first wearable audio device; or whether a second wearable audio device is engaged with or removed form a second ear of a user, using a second sensor of the second wearable audio device; and automatically adjusting the one or more ANR parameters of the first and/or second wearable audio device to a second ANR state when either the first wearable audio device or the second wearable audio device, or both, are removed from an ear of the user, wherein the second ANR state comprises a reduction in a level of ANR at least at some frequencies compared to the first ANR state. 
     In an aspect, the method further comprises: detecting whether the first wearable audio device is engaged with or removed from a first ear of the user using a first sensor of the first wearable audio device and detecting whether the second wearable audio device is engaged with or removed from a second ear of the user using a second sensor of the second wearable audio device; and automatically adjusting the one or more ANR parameters of the first and second wearable audio device to the first ANR state when both the first and second wearable audio device are detected to be engaged with an ear of the user. 
     In an aspect, the one or more ANR parameters relate to at least one of a feedback filter, a feedforward filter, and an audio equalization. 
     In an aspect, the one or more ANR parameters of the second ANR state comprise at least one of: default settings or user-set ANR settings that are input by the user. 
     In an aspect, the one or more ANR parameters of the first ANR state comprise at least one of: default settings, user-set ANR settings that are input by the user, or a last-used ANR settings. 
     In an aspect, in the second ANR state, the first and second wearable audio device can be utilized to perform at least one of the following: start an audio signal to be reproduced by the audio system; stop an audio signal from being reproduced by the audio system; pause the audio signal that was being reproduced by the audio system; answer a phone call; decline a phone call; accept a notification; dismiss a notification; and access a voice assistant. 
     In an aspect, the first and second wearable audio device are arranged to operate in a plurality of ANR states during which the one or more ANR parameters are adjusted using a user interface to increase or decrease noise reduction. 
     In an aspect, the first sensor of the first wearable audio device and the second sensor of the second wearable audio device comprise at least one of: a gyroscope, an accelerometer, an infrared sensor, a magnetometer, an acoustic sensor, a motion sensor, a piezoelectric sensor, a piezoresistive sensor, a capacitive sensor, and a magnetic field sensor. 
     Generally, in one aspect, a computer program product comprising a set of non-transitory computer readable instructions stored on a memory and executable by a processor to perform a method for controlling an Active Noise Reduction (ANR) audio system is provided. The set of non-transitory computer readable instructions are arranged to: generate one or more control signals, using a controller, to set one or more ANR parameters of a first and a second wearable audio device to a first ANR state; detect at least one of: whether the first wearable audio device is engaged with or removed from a first ear of a user, using a first sensor of the first wearable audio device; or whether a second wearable audio device is engaged with or removed form a second ear of a user, using a second sensor of the second wearable audio device; and automatically adjust the one or more ANR parameters of the first and/or second wearable audio device to a second ANR state when either the first wearable audio device or the second wearable audio device, or both, are removed from an ear of the user, wherein the second ANR state comprises a reduction in a level of ANR at least at some frequencies compared to the first ANR state. 
     In an aspect, the set of non-transitory computer readable instructions further arranged to: detect whether the first wearable audio device is engaged with or removed from a first ear of the user using a first sensor of the first wearable audio device and detect whether the second wearable audio device is engaged with or removed from a second ear of the user using a second sensor of the second wearable audio device; and automatically adjust the one or more ANR parameters of the first and second wearable audio device to the first ANR state when both the first and second wearable audio device are detected to be engaged with an ear of the user. 
     In an aspect, the one or more ANR parameters relate to at least one of a feedback filter, a feedforward filter, and an audio equalization. 
     In an aspect, the one or more ANR parameters of the second ANR state comprise at least one of: default settings or user-set ANR settings that are input by the user. 
     In an aspect, the first and second wearable audio device are arranged to operate in a plurality of ANR states during which the one or more ANR parameters are adjusted using a user interface to increase or decrease noise reduction. 
     Generally, in one aspect, an Active Noise Reduction (ANR) audio system comprising a first wearable audio device and a second wearable audio device is provided. The first wearable audio device comprises: a first sensor arranged to determine if the first wearable audio device is engaged with or removed from a first ear of a user. The second wearable audio device comprises: a second sensor arranged to determine if the second wearable audio device is engaged with or removed from a second ear of the user. The audio system comprises a controller arranged to: generate one or more control signals to set one or more ANR parameters of the first and the second wearable audio device to a first ANR state; detect at least one of: whether the first wearable audio device is engaged with or removed from a first ear of a user, using a first sensor of the first wearable audio device or whether a second wearable audio device is engaged with or removed form a second ear of a user, using a second sensor of the second wearable audio device; and automatically adjust the one or more ANR parameters of the first and/or second wearable audio device to a second ANR state when either the first wearable audio device or the second wearable audio device, or both, are removed from an ear of the user, wherein the second ANR state comprises a reduction in a level of ANR at least at some frequencies compared to the first ANR state. 
     In an aspect, the controller is further arranged to: detect whether the first wearable audio device is engaged with or removed from the first ear of the user using the first sensor of the first wearable audio device and detecting whether the second wearable audio device is engaged with or removed from the second ear of the user using the second sensor of the second wearable audio device; and automatically adjust the one or more ANR parameters of the first and second wearable audio device to the first ANR state when both the first and second wearable audio device are detected to be engaged with an ear of the user. 
     In an aspect, the first and second wearable audio device are arranged to operate in a plurality of ANR states during which the one or more ANR parameters are adjusted using a user interface to increase or decrease noise reduction. 
     In an aspect, the first wearable audio device further comprises a first user interface adapted to receive user input to increase or decrease noise reduction. 
     In an aspect, the first wearable audio device further comprises a first outer surface, the first outer surface comprising a first touch capacitive sensor. 
     In an aspect, the controller is arranged within, around, or proximate to the first wearable audio device or the second wearable audio device. 
     In an aspect, the first sensor of the first wearable audio device and the second sensor of the second wearable audio device comprise at least one of: a gyroscope, an accelerometer, an infrared sensor, a magnetometer, an acoustic sensor, a motion sensor, a piezoelectric sensor, a piezoresistive sensor, a capacitive sensor, and a magnetic field sensor. 
     These and other aspects of the various illustrations will be apparent from and elucidated with reference to the aspect(s) described hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the various aspects. 
         FIG. 1  illustrates an example of an audio system of the present disclosure. 
         FIG. 2A  illustrates a first headphone according to an example of the present disclosure. 
         FIG. 2B  illustrates a second headphone according to an example of the present disclosure. 
         FIG. 3A  schematically illustrates one example configuration of components included in a first headphone according to the present disclosure. 
         FIG. 3B  schematically illustrates one example configuration of components included in a second headphone according to the present disclosure. 
         FIG. 4  is a schematic diagram of an exemplary active noise reduction system incorporating feedback and feedforward components. 
         FIG. 5  is a flow-chart illustrating the steps of a method according to aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In headphones, such as wireless headphones, that have Active Noise Reduction (“ANR”) capability, different ANR settings may provide different levels of noise reduction. The present disclosure provides methods and systems directed to automatically adjusting the ANR parameters that alter noise reduction levels in the headphones based on whether the headphones are engaged with or removed from a user ear. According to an example, the system detects whether one or both of a first headphone and a second headphone are engaged with a user&#39;s ear. If both headphones are engaged with a user&#39;s ear, then the ANR subsystem automatically adjusts the ANR settings of the two headphones to bring the headphones to a first ANR state with either a default high level of noise reduction, a user-selected level of noise reduction, or the last selected level of noise reduction. If one or both headphones are removed from the ear, both headphones are brought to a second ANR state with lower levels of noise reduction. This enables a user to have lower noise reduction settings in a headphone engaged with the ear after removing the other headphone from the ear, to for example, have a conversation with someone. When both headphones are returned to the ear, the system automatically raises the noise reduction levels to those used in the first ANR state. 
     ANR subsystems are used for cancelling or reducing unwanted or unpleasant noise. An ANR subsystem can include an electroacoustic system that can be configured to cancel at least some of the unwanted noise (often referred to as primary noise) based on the principle of superposition. This can be done by identifying an amplitude and phase of the primary noise and producing another signal (often referred to as an anti-noise signal) of about equal amplitude and opposite phase. An appropriate anti-noise signal combines with the primary noise such that both are substantially canceled at the location of an error sensor (e.g., canceled to within a specification or acceptable tolerance). In this regard, in the example implementations described herein, “canceling” noise may include reducing the “canceled” noise to a specified level or to within an acceptable tolerance, and does not require complete cancellation of all noise. Noise canceling systems may include feedforward and/or feedback signal paths. A feedforward component detects noise external to the headset (e.g., via an external microphone) and acts to provide an anti-noise signal to counter the external noise expected to be transferred through to the user&#39;s ear. A feedback component detects acoustic signals reaching the user&#39;s ear (e.g., via an internal microphone) and processes the detected signals to counteract any signal components not intended to be part of the user&#39;s acoustic experience. Although described herein as coupled to, or placed in connection with, other systems, through wired or wireless means, it should be appreciated that noise cancelling systems may be independent of any other systems or equipment. 
     The term “wearable audio device” as used herein is intended to mean a device that fits around, on, in, or near an ear and that radiates acoustic energy into or towards the ear canal. Wearable audio devices are sometimes referred to as headphones, earphones, earpieces, headsets, earbuds or sport headphones, and can be wired or wireless. A wearable audio device includes an acoustic driver to transduce audio signals to acoustic energy. The acoustic driver may be housed in an earcup. While some of the figures and descriptions following may show a single wearable audio device, a wearable audio device may be a single stand-alone unit or one of a pair of wearable audio devices (each including a respective acoustic driver and earcup), one for each ear. A wearable audio device may be connected mechanically to another wearable audio device, for example by a headband and/or by leads that conduct audio signals to an acoustic driver in the wearable audio device. A wearable audio device may include components for wirelessly receiving audio signals. A wearable audio device may include components of an active noise reduction system. Wearable audio devices may also include other functionality such as a microphone so that they can function as a headset. While  FIG. 1  shows an example of an around-ear headset, in other examples the headset may be an in-ear, on-ear, or near-ear headset. In some examples, a wearable audio device may be an open-ear device that includes an acoustic driver to radiate acoustic energy towards the ear canal while leaving the ear open to its environment and surroundings. 
     Referring now to the drawings,  FIG. 1  schematically illustrates audio system  100 . Audio system  100  generally includes first headphone  102 , second headphone  104 , and peripheral device  106 . First headphone  102  and second headphone  104  are both arranged to communicate with peripheral device  106  and/or communicate with each other. Peripheral device  106  may be any device capable of establishing a connection with first headphone  102  and/or second headphone  104 , either wirelessly through wireless protocols known in the art, or via a wired connection, i.e., via a cable capable of transmitting a data signal from peripheral device  106  to first headphone  102  or second headphone  104 . In one example, first headphone  102  and second headphone  104  are in ear or on ear earbuds each arranged to communicate wirelessly with a peripheral device  106 . In one example, peripheral device  106  is a smartphone having a computer executable application installed thereon such that the connection between peripheral device  106 , first headphone  102  and/or second headphone  104  can be mutually established using a user interface on peripheral device  106 . 
       FIG. 2A  illustrates first headphone  102 . First headphone  102  includes a housing, which further includes first driver  108 , which is an acoustic transducer for conversion of, e.g., an electrical signal, into an audio signal that the user may hear, and (referring to  FIG. 3A ) first antenna  110 . The first audio signal may correspond to data related to at least one digital audio file, which can be streamed over a wireless connection to peripheral device  106  or first headphone  102 , stored in first memory  112  (discussed below), or stored in the memory of peripheral device  106 . First antenna  110  is arranged to send and receive wireless communication information from, e.g., second headphone  104  or peripheral device  106 . As an example, first headphone  102  and second headphone  104  are each capable of wireless communication with a peripheral device  106 . First headphone  102  includes a controllable ANR subsystem. First headphone  102  includes one or more microphones, such as a first feedforward microphone  114  and/or a first feedback microphone  116 . The first feedforward microphone  114  may be configured to sense acoustic signals external to the first headphone  102  when worn, e.g., to detect acoustic signals in the surrounding environment before they reach the user&#39;s ear. The feedback microphone  116  may be configured to sense acoustic signals internal to an acoustic volume formed with the user&#39;s ear when the first headphone  102  is worn, e.g., to detect the acoustic signals reaching the user&#39;s ear. In various examples, one or more drivers may be included in a headphone, and a headphone may in some cases include only a feedforward microphone or only a feedback microphone, or multiple feedforward and/or feedback microphones. Returning to  FIG. 2A , the housing further includes first outer surface  115  having a sensor arranged thereon. In one example, the sensor on first outer surface  115  of first headphone  102  is a touch capacitive sensor, e.g., first touch capacitive sensor  117 . First touch capacitive sensor  117  is arranged to receive at least one user input corresponding to at least one first user control setting  119  of first set of user control settings  128  discussed with reference to  FIG. 3A . At least one user input can include a swipe gesture (e.g., movement across first touch capacitive sensor  117 ), a single-tap, a double-tap (tapping at least two times over a predetermined period of time), triple-tap (tapping at least three times over a predetermined period of time) or any other rhythmic cadence/interaction with first touch capacitive sensor  117 . It should also be appreciated that at least one user input could be an input from a sensor such as a gyroscope or accelerometer, e.g., when user U removes first headphone  102  from ear E, the gyroscope or accelerometer may measure a specified rotation, acceleration, or movement, indicative of user U removing the first headphone  102  from ear E. Additionally, first headphone  102  may also include first sensor  118  in order to detect proximity to or engagement with ear E of user U. Although shown in  FIG. 2A  as being arranged on an ear tip of first headphone  103 , first sensor  118  could alternatively be arranged on or within the housing of first headphone  102 . First sensor  118  can be any of: a gyroscope, an accelerometer, a magnetometer, an infrared (IR) sensor, an acoustic sensor (e.g., a microphone or acoustic driver), a motion sensor, a piezoelectric sensor, a piezoresistive sensor, a capacitive sensor, a magnetic field sensor, or any other sensor known in the art capable of determining whether first headphone  102  is proximate to, engaged with, within, or removed from ear E of user U. 
     Referring to  FIG. 3A , first headphone  102  further includes first controller  120 . In an example, first controller  120  includes at least first processor  122  and first memory  112 . The first processor  122  and first memory  112  of first controller  120  are arranged to receive, send, store, and execute any of a plurality of ANR parameters  125 , a first set of ANR parameters  124 , and/or a second set of ANR parameters  126  which may relate to a feedback filter, a feedforward filter, or audio equalization, based on a signal from the first feedforward microphone  114  and/or first feedback microphone  116 . The first processor  122  and first memory  112  of first controller  120  are arranged to receive, send, store, and execute at least one first user control setting  119  of a first set of user control settings  128 . In an example, first set of user control settings  128  can include settings such as, but not limited to: increase or decrease volume of the audio signal being reproduced by the audio system  100 ; increase or decrease noise reduction by an controller; start/play/stop/pause the audio signal being reproduced by the audio system  100 ; answer or decline a phone call; accept or dismiss a notification; and access a voice assistant, such as Alexa, Google Assistant, or Siri. The functions of the controller  120  may be performed by one or more separate controllers, which may be arranged to communicate with and operate in conjunction with each other. As an example, one controller may be arranged to receive, send, store, and execute any of a plurality of ANR parameters  125 , a first set of ANR parameters  124 , and/or a second set of ANR parameters  126 , and a separate controller may be arranged to receive, send, store, and execute at least one first user control setting  119  of a first set of user control settings  128 . 
       FIG. 2B  illustrates second headphone  104 . Second headphone  104  also includes a housing, which further includes second driver  130  arranged to reproduce a second audio signal and (referring to  FIG. 3B ) second antenna  132 . The second audio signal may correspond to data related to at least one digital audio file which can be streamed over a wireless connection to first headphone  102  or second headphone  104 , stored in second memory  134  (discussed below), or stored in the memory of peripheral device  106 . Second antenna  132  is arranged to send and receive wireless communication information from, e.g., first headphone  102  or peripheral device  106 . As an example, first headphone  102  and second headphone  104  are each capable of wireless communication with a peripheral device  106 . Second headphone  104  also includes a controllable ANR subsystem. Second headphone  104  includes one or more microphones, such as a second feedforward microphone  136  and/or a second feedback microphone  138 . In various examples, one or more drivers may be included in a headphone, and a headphone may in some cases include only a feedforward microphone or only a feedback microphone, or multiple feedforward and/or feedback microphones. In one example, the sensor on second outer surface  135  of second headphone  104  is a touch capacitive sensor, e.g., second touch capacitive sensor  137 . Second touch capacitive sensor  137  is arranged to receive at least one user input corresponding to at least one second user control setting  139  of second set of user control settings  146  discussed below. As discussed above with respect to first headphone  102 , the at least one user input can include a swipe gesture (e.g., movement across second touch capacitive sensor  137 ), a single-tap, a double-tap (tapping at least two times over a predetermined period of time), triple-tap (tapping at least three times over a predetermined period of time) or any other rhythmic cadence/interaction with second touch capacitive sensor  137 . It should also be appreciated that at least one user input could be an input from a sensor such as a gyroscope or accelerometer, e.g., when user U removes second headphone  104  from ear E, the gyroscope or accelerometer may measure a specified rotation, acceleration, or movement, indicative of user U removing the second headphone  104  from ear E. Additionally, second headphone  104  may also include second sensor  140  in order to detect proximity to or engagement with ear E of user U. Although shown in  FIG. 2B  as being arranged on an ear tip of second headphone  104 , second sensor  140  could alternatively be arranged on or within the housing of second headphone  104 . Second sensor  140  can be any of: a gyroscope, an accelerometer, a magnetometer, an infrared (IR) sensor, an acoustic sensor (e.g., a microphone or acoustic driver), a motion sensor, a piezoelectric sensor, a piezoresistive sensor, a capacitive sensor, a magnetic field sensor, or any other sensor known in the art capable of determining whether second headphone  104  is proximate to, engaged with, within, or removed from ear E of user U. 
     Referring to  FIG. 3B , second headphone  104  further includes second controller  142 . In an example, second controller  142  includes at least second processor  144  and second memory  134 . The second processor  144  and second memory  134  of second controller  142  are arranged to receive, send, store, and execute any of a plurality of ANR parameters  125 , a first set of ANR parameters  124 , and/or a second set of ANR parameters  126  which may relate to a feedback filter, a feedforward filter, and an audio equalization, based on a signal from a second feedforward microphone  136  and/or second feedback microphone  138 . The second processor  144  and second memory  134  of second controller  142  are also arranged to receive, send, store, and execute at least one second user  139  control setting of a second set of user control settings  146 . The functions of the controller  142  may be performed by one or more separate controllers, which may be arranged to communicate with and operate in conjunction with each other. As an example, one controller may be arranged to receive, send, store, and execute any of a plurality of ANR parameters  125 , a first set of ANR parameters  124 , and/or a second set of ANR parameters  126 , and a separate controller may be arranged to receive, send, store, and execute at least one second user control setting  139  of a second set of user control settings  146 . As another example, only one of the first controller  124  or the second controller  142  may be present in both the first headphone  102  and the second headphone  104 . In that case, the controller which is present in the first headphone or second headphone may detect whether one or both of the first headphone and the second headphone are engaged with or removed from the ear of a user and adjust ANR parameters in one or both headphones. 
       FIG. 4  illustrates an exemplary system and method of processing microphone signals, for example in the first headphone  102 , to reduce noise reaching the ear E of user U.  FIG. 4  presents a simplified schematic diagram to highlight features of a noise reduction system. Various examples of a complete system may include amplifiers, analog-to-digital conversion (ADC), digital-to-analog conversion (DAC), equalization, sub-band separation and synthesis, and other signal processing or the like. In some examples, a playback signal  148 , p(t), may be received to be rendered as an acoustic signal by the first driver  108 . The first feedforward microphone  114  may provide a feedforward signal  150  that is processed by a feedforward processor  122 A of the first processor  122 , having a feedforward transfer function  156 , Kff, to produce a feedforward anti-noise signal  152 . The first feedback microphone  116  may provide a feedback signal  154  that is processed by a feedback processor  122 B of the first processor  122 , having a feedback transfer function  158 , Kfb, to produce a feedback anti-noise signal  160 . In various examples, any of the playback signal  148 , the feedforward anti-noise signal  152 , and/or the feedback anti-noise signal  160  may be combined, e.g., by a combiner  162 , to generate a driver signal  164 , d(t), to be provided to the first driver  108 . In various examples, any of the playback signal  148 , the feedforward anti-noise signal  152 , and/or the feedback anti-noise signal  160  may be omitted and/or the components necessary to support any of these signals may not be included in a particular implementation of a system. Although the above example is provided on an ANR subsystem of the first headphone  102 , the second headphone  104  is capable of providing noise cancellation and includes second controller  142 , second processor  144 , second feedforward microphone  136 , and feedback microphone  138 , and second driver  124  to perform noise reduction. 
     Different ANR settings providing different levels of noise reduction may be desirable to a user based on user preferences, system settings, and operational mode. For example, a user may desire more noise reduction based on environmental conditions and desire ANR settings that are more aggressive and cancel more noise and/or noise in a wider range of frequencies. Another user may desire less noise reduction, for example in order to hear more noise from the external environment, and desire less aggressive ANR settings that cancel less noise and/or noise in a narrower range of frequencies. To achieve different levels of noise reduction, different ANR parameters may be varied, for example, feedback filter settings, e.g., the gain and/or phase associated with a filter applied to a feedback microphone, e.g. first feedback microphone  116  or second feedback microphone  138 , of the controllable ANR subsystem; feedforward filter settings, e.g., the gain and/or phase associated with a filter applied to a feedforward microphone, e.g. first feedforward microphone  114  or second feedforward microphone  136 , of the ANR subsystem; audio equalization settings, and various other parameters of the noise reduction system, such as, for example, a driver signal amplitude (e.g., mute, reduce, or limit the driver signal  164 ). 
     During operation of audio system  100 , first headphone  102  and/or second headphone  104  can pair (e.g. using known Bluetooth, Bluetooth Low Energy, or other wireless protocol pairing) or connect with peripheral device  106 , e.g., a smartphone. An audio stream may be established between peripheral device  106 , first headphone  102 , and second headphone  104 . The audio stream can include data relating to an audio file streamed over a wireless connection or a stored audio file. An ANR subsystem may be operational on the first headphone  102  and second headphone  104  having automatic ANR settings, which are set based on whether the headphones are engaged with or removed from a user&#39;s ear. The first sensor  118  and the second sensor  140  detect whether the first headphone  102  and the second headphone  104 , respectively, are engaged with or removed from a user&#39;s ear. When both the first headphone  102  and the second headphone  104  are engaged with an ear of the user, the ANR settings of both headphones  102 / 104  are automatically adjusted to a first ANR state with a first set of ANR parameters, which may include one of: a default level of noise reduction, which may be a higher noise reduction setting to block unwanted noise from the environment; a user-selected level of noise reduction; or the last selected level of noise reduction. If a user removes one headphone  102 / 104  from the ear, the ANR settings are automatically adjusted by the first controller  120  and/or the second controller  142  to bring both headphones  102 / 104  to a second ANR state with a second set of ANR parameters, which may permit more of the environment to pass through the headphones  102 / 104 . In this second ANR state, ANR may be lower than in the first ANR state at least at some frequencies, for example the frequencies that typically contain human speech sounds (e.g., 140 Hz to 5 kHz). Examples of technologies that can be used in the second ANR state to permit more of the environment to pass through the headphones  102 / 104  are described in U.S. Pat. Nos. 8,798,283; 9,949,017; and 10,096,313, each of which is incorporated herein by reference in its entirety. If the user has only removed the first headphone  102  from the ear, for example, to engage in a conversation with someone, the noise cancellation of the second headphone  104  is modified (as described above) to allow the conversation to be heard through the second headphone  104 . In some examples, the noise cancellation of the first headphone  102  is also modified in the same manner. As another example, during the second ANR state, the headphones could take additional actions to make it easier for noise from the environment to be heard. For example, the volume on audio content may be reduced, audio content may be paused, audio content or phone conversation may be muted, or additional microphones on the headphone still engaged with a user&#39;s ear may be enabled which focus on environmental noise. When both headphones  102 / 104  are removed from the ears, the first controller  120  or second controller  142  also automatically adjusts the ANR parameters of both headphones  102 / 104  to bring both headphones  102 / 104  to the second ANR state. If a user then returns one or both headphones  102 / 104  to the ears, for example, after finishing a conversation, then the controller (either the first controller  120 , the second controller  142 , or both controllers) then automatically brings the headphones  102 / 104  to the first ANR state, which in some examples has greater noise reduction and can block more noise from the environment. 
     As an example, the ANR parameters of the first state and the second state may be default settings which are preprogrammed into the headphones  102 / 104 , for example, during the manufacturing and assembly of the headphones. As another example, the ANR parameters may be adjustable so that a user can adjust the ANR parameters for the first ANR state and/or the second ANR state so that the level of noise reduction when the headphones operate in those states, for example, based on whether both headphones  102 / 104  are inserted in both ears, is adjusted. For example, a user may want less noise reduction when the headphones are operating in the second state, so that, as an example, the user can hear certain environmental noise like car horns or emergency vehicle sirens, or a desired amount of conversation through the headphone that is still in the user&#39;s ear. As another example, a user may desire less or more noise reduction in the first ANR state, for example, to be able to cancel unwanted environmental noise, e.g., airplane noise. The user may be able to adjust the ANR parameters of the first and/or second ANR state. As another example, the audio system  100  may be capable of operating in a plurality of ANR states, with a plurality of ANR parameters  125 , where additional ANR states are available to a user in addition to the first ANR state and the second ANR state. These states may be preprogramed into the audio system or adjustable by the user. As an example, the user may be able to increase or decrease noise reduction using a user interface, e.g., first touch capacitive sensor  117  and/or second touch capacitive sensor  137 . Systems with multiple ANR states are described in the applications that have been incorporated by reference herein. 
       FIG. 5  is a flow-chart illustrating the steps of a method for controlling an audio system  100  according to aspects of the present disclosure. The method  200  includes the steps of: generating one or more control signals, using an Active Noise Reduction (ANR) controller  120 / 142 , to set one or more ANR parameters of a first headphone  102  and a second headphone  104  to a first ANR state (step  210 ); detecting, at a first sensor  118  of the first headphone  102 , whether the first headphone  102  is engaged with or removed from a first ear of a user (step  220 ); detecting, at a second sensor  140  of the second headphone  104 , whether the second headphone  104  is engaged with or removed from a second ear of the user (step  230 ); automatically adjusting the one or more ANR parameters of the first headphone  102  and the second headphone  104  to a second ANR state when either the first headphone  102  or the second headphone  104 , or both, are removed from an ear of the user, wherein the second ANR state comprises a reduction in a level of ANR at least at some frequencies compared to the first ANR state (step  240 ); automatically adjusting the one or more ANR parameters of the first headphone  102  and second headphone  104  to the first ANR state when both the first headphone  102  and second headphone  104  are detected to be engaged with an ear of the user (step  250 ). 
     A computer program product for performing a method for controlling an audio system  100  can have a set of non-transitory computer readable instructions. The set of non-transitory computer readable instructions can be stored and executed on a memory  112 / 134  and a processor  122 / 144  of a first headphone  102  and second headphone  104  (shown in  FIGS. 2A and 2B ). The set of non-transitory computer readable instructions can be arranged to: generate one or more control signals, using an Active Noise Reduction (ANR) controller  120 / 142 , to set one or more ANR parameters of a first headphone  102  and a second headphone  104  to a first ANR state; detect, at a first sensor  118  of the first headphone  102 , whether the first headphone  102  is engaged with or removed from a first ear of a user; detect, at a second sensor  140  of the second headphone  104 , whether the second headphone  104  is engaged with or removed from a second ear of the user; automatically adjust the one or more ANR parameters of the first headphone  102  and the second headphone  104  to a second ANR state when either the first headphone  102  or the second headphone  104 , or both, are removed from an ear of the user, wherein the second ANR state comprises a reduction in a level of ANR at least at some frequencies compared to the first ANR state; automatically adjust the one or more ANR parameters of the first headphone  102  and second headphone  104  to the first ANR state when both the first headphone  102  and second headphone  104  are detected to be engaged with an ear of the user. 
     The above-described examples of the described subject matter can be implemented in any of numerous ways. For example, some aspects may be implemented using hardware, software or a combination thereof. When any aspect is implemented at least in part in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single device or computer or distributed among multiple devices/computers. 
     The present disclosure may be implemented as a system, a method, and/or a computer program product at any possible technical detail level of integration. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present disclosure. 
     The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
     Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device. 
     Computer readable program instructions for carrying out operations of the present disclosure may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuitry, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++, or the like, and procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some examples, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present disclosure. 
     Aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to examples of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
     The computer readable program instructions may be provided to a processor of a, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram or blocks. 
     The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various examples of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     Other implementations are within the scope of the following claims and other claims to which the applicant may be entitled. 
     While various examples have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the examples described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific examples described herein. It is, therefore, to be understood that the foregoing examples are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, examples may be practiced otherwise than as specifically described and claimed. Examples of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.