PATENT DOCUMENT

Publication Number: US-11375333-B1
Application Number: US-202017023160-A
Country: US
Kind Code: B1

Title: Spatial audio reproduction based on head-to-torso orientation

Abstract:
A media system and a method of using the media system to reproduce spatial audio based on head-to-torso orientation, are described. The method includes determining a head-to-source orientation and a head-to-torso orientation based on head orientation data generated by a head tracking device. Determining the head-to-torso orientation includes determining torso movements based on movements of the head. The torso can be determined to move when the head movements meet a head movement condition, such as a predetermined angle of movement or pattern of movement. A binaural audio filter that is based on a head-related transfer function corresponding to both the head-to-source orientation and the head-to-torso orientation is applied to an audio input signal to generate an audio output signal. The audio output signal is played to accurately recreate spatial audio having sounds emitted to the user by a sound source. Other aspects are also described and claimed.

Claims:
What is claimed is: 
     
       1. A method, comprising:
 determining a head-to-source orientation between a head of a user and a sound source based on head orientation data generated by a head tracking device; 
 determining a head-to-torso orientation between the head and a torso of the user, wherein the head-to-torso orientation is based on the head orientation data and torso orientation data, and wherein the torso orientation data is derived from the head orientation data based on movements of the torso that accompany movements of the head; 
 applying a binaural audio filter to an audio input signal to generate an audio output signal, wherein the binaural audio filter is based on a head-related transfer function (HRTF) corresponding to the head-to-source orientation and the head-to-torso orientation; and 
 playing the audio output signal to recreate spatial audio of sounds emitted to the user by the sound source. 
 
     
     
       2. The method of  claim 1 , wherein determining the torso orientation data includes determining that the torso moves toward alignment with the head when the head orientation data meets a head movement condition. 
     
     
       3. The method of  claim 2 , wherein the head movement condition includes movement of the head from a first head orientation to a second head orientation and resting the head at the second orientation for a predetermined period of time. 
     
     
       4. The method of  claim 2 , wherein the head movement condition includes movement of the head by a predetermined angle. 
     
     
       5. The method of  claim 4 , wherein the predetermined angle includes one or more of a yaw angle, a pitch angle, or a roll angle. 
     
     
       6. The method of  claim 2 , wherein the head movement condition includes movement of the head matching a pattern of head movement of one or more other users. 
     
     
       7. The method of  claim 1 , wherein determining the head-to-torso orientation is based on contextual information about one or more of a current state of the user or a current use of the head tracking device. 
     
     
       8. The method of  claim 7 , wherein the contextual information indicates that the user is ambulatory such that the head-to-torso orientation includes the head relative to a vertically-oriented torso. 
     
     
       9. The method of  claim 7 , wherein the contextual information indicates that the head tracking device is being used to play audio content of a movie such that the head-to-torso orientation includes the head aligned to the torso. 
     
     
       10. The method of  claim 1  further comprising selecting the HRTF from an HRTF database, wherein the HRTF database includes a plurality of numerically simulated HRTFs for respective combinations of head-to-source orientations and head-to-torso orientations. 
     
     
       11. The method of  claim 1 , wherein the audio input signal represents a sound being produced by the sound source. 
     
     
       12. A media system, comprising:
 one or more processors configured to:
 determine a head-to-source orientation between a head of a user and a sound source based on head orientation data generated by a head tracking device, 
 determine a head-to-torso orientation between the head and a torso of the user, wherein the head-to-torso orientation is based on the head orientation data and torso orientation data, and wherein the torso orientation data is derived from the head orientation data based on movements of the torso that accompany movements of the head, and 
 apply a binaural audio filter to an audio input signal to generate an audio output signal, wherein the binaural audio filter is based on a head-related transfer function (HRTF) corresponding to the head-to-source orientation and the head-to-torso orientation; and 
 
 one or more speakers configured to play the audio output signal to recreate spatial audio of sounds emitted to the user by the sound source. 
 
     
     
       13. The media system of  claim 12 , wherein the head tracking device is a head mounted device. 
     
     
       14. The media system of  claim 12 , wherein determining the torso orientation data includes determining that the torso moves toward alignment with the head when the head orientation data meets a head movement condition. 
     
     
       15. The media system of  claim 12 , wherein determining the head-to-torso orientation is based on contextual information about one or more of a current state of the user or a current use of the head tracking device. 
     
     
       16. The media system of  claim 12  further comprising a memory storing an HRTF database including a plurality of numerically simulated HRTFs for respective combinations of head-to-source orientations and head-to-torso orientations;
 wherein the one or more processors are further configured to select the HRTF from the HRTF database. 
 
     
     
       17. The media system of  claim 12 , wherein the audio input signal represents a sound being produced by the sound source. 
     
     
       18. A non-transitory computer readable medium containing instructions, which when executed by one or more processors of a media system, cause the media system to perform a method comprising:
 determining a head-to-source orientation between a head of a user and a sound source based on head orientation data generated by a head tracking device; 
 determining a head-to-torso orientation between the head and a torso of the user, wherein the head-to-torso orientation is based on the head orientation data and torso orientation data, and wherein the torso orientation data is derived from the head orientation data based on movements of the torso that accompany movements of the head; 
 applying a binaural audio filter to an audio input signal to generate an audio output signal, wherein the binaural audio filter is based on a head-related transfer function (HRTF) corresponding to the head-to-source orientation and the head-to-torso orientation; and 
 playing the audio output signal to recreate spatial audio of sounds emitted to the user by the sound source. 
 
     
     
       19. The non-transitory computer readable medium of  claim 18 , wherein determining the torso orientation data includes determining that the torso moves toward alignment with the head when the head orientation data meets a head movement condition. 
     
     
       20. The non-transitory computer readable medium of  claim 19 , wherein the head movement condition includes movement of the head from a first head orientation to a second head orientation and resting the head at the second orientation for a predetermined period of time. 
     
     
       21. The non-transitory computer readable medium of  claim 19 , wherein the head movement condition includes movement of the head by a predetermined angle. 
     
     
       22. The non-transitory computer readable medium of  claim 18 , wherein determining the head-to-torso orientation is based on contextual information about one or more of a current state of the user or a current use of the head tracking device. 
     
     
       23. The non-transitory computer readable medium of  claim 18 , wherein the audio input signal represents a sound being produced by the sound source.

Description:
This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/903,430, filed Sep. 20, 2019, and incorporates herein by reference that provisional patent application. 
    
    
     BACKGROUND 
     Field 
     Aspects related to audio systems are disclosed. More particularly, aspects related to audio systems used to render spatial audio are disclosed. 
     Background Information 
     Spatial audio can be played using headphones that are worn by a user. For example, the headphones can reproduce a spatial audio signal communicated by a device to simulate a soundscape around the user. An effective spatial sound reproduction can recreate sounds such that the user perceives the sound as coming from a location within the soundscape external to the user&#39;s head, just as the user would experience the sound if encountered in the real world. 
     When a sound travels to a listener from a surrounding environment in the real world, the sound propagates along a direct path, e.g., through air to the listener&#39;s ear canal entrance, and along one or more indirect paths, e.g., by reflecting and diffracting around the listener&#39;s head or shoulders. As the sound travels along the indirect paths, artifacts can be introduced into the acoustic signal that the ear canal entrance receives. User-specific artifacts can be incorporated into binaural audio by signal processing algorithms that use spatial audio filters. For example, a head-related transfer function (HRTF) describes how a sound located somewhere in space, relative to a listener&#39;s body, is filtered, e.g., reflected or diffracted around the listener&#39;s head, torso, and outer ear, before entering their auditory system. The HRTF-described cues allow the auditory system to determine where in space a sound is coming from. 
     To implement accurate spatial audio reproduction, a virtual audio system can use the HRTF to create the illusion that sound is coming from somewhere in space. More particularly, an HRTF-related audio filter can be applied to an audio input signal to shape the signal in such a way that reproduction of the shaped signal realistically simulates a sound traveling to the user from the relative location at which the HRTF was measured. Accordingly, a listener can use simple stereo headphones to create the illusion of a sound source somewhere in a listening environment by applying the binaural audio filter to the audio input signal. 
     SUMMARY 
     Existing virtual audio rendering systems are required to know the user&#39;s head orientation relative to the virtual sound source in order to select an appropriate head-related transfer function (HRTF). Typically, the HRTF is defined and measured as having a dependence on an azimuth angle, elevation angle, and sometimes a distance between the virtual sound source and the user&#39;s head. Definitions of the HRTF dataset up until now do not encapsulate the dimension related to the orientation of the rest of the body relative to the user&#39;s head. More particularly, changes away from a nominal forward-facing head-to-torso orientation are not accounted for when using a HRTF dataset; the torso is assumed to rotate and move with the head. Thus, a user that turns his head to the right while keeping his torso stationary, e.g., facing forward, will have the unsettling experience of hearing sound as though he turned his torso to the right concurrently with his head. In other words, the virtual audio rendering systems do not differentiate between cases when the head and torso are moved separately and cases when the head and torso are moved together. This disregard for head-to-torso orientations by existing virtual audio rendering systems results in spatial audio renderings that do not accurately reproduce the effects that the torso orientation has on sound sources in real life. 
     A media system and a method of using the media system to accurately reproduce virtual audio taking into account a user&#39;s head orientation relative to the user&#39;s torso, are described. In an embodiment, the media system includes one or more processors configured to determine a head-to-source orientation and a head-to-torso orientation. The head-to-source orientation can be a relative position and/or orientation between a head of a user and a sound source. The relative orientation can be determined from head tracking data generated by a head tracking device, such as a head mounted device having inertial measurement units. The head-to-torso orientation can be a relative position and/or orientation between the head of the user and a torso of the user. The relative orientation can be directly measured, e.g., by one or more sensors of the head tracking device or a companion device. Alternatively, the relative orientation can be inferred based only on the head tracking data generated by the head tracking device. 
     Estimation of the head-to-torso orientation based on the head tracking data can include determining that the torso moves toward alignment with the head when the head orientation data meets a head movement condition. For example, the torso may move when the head moves. Alternatively, the torso may move when the head has moved and then stopped moving at a new orientation. In an aspect, the torso may move when the head moves in a particular pattern. In any case, the movement of the torso can be related to the head movement, e.g., numerically through an average or median of head tracking data, or in some other manner, e.g., by moving the torso according to a particular pattern that corresponds to the pattern detected for the head movement. 
     Inference of the head-to-torso orientation can also be based on contextual data that exists at the time of the head movement. For example, the inference may be based on a current state of the user, e.g., whether the user is ambulatory, or a current use of the head tracking device, e.g., whether the system is being used to reproduce a soundscape of a movie. In any case, the contextual information can provide additional information to control whether or how the estimation of torso movement is made. 
     Based on the head-to-source orientation and the head-to-torso orientation (whether measured or inferred), the media system can select an appropriate head-related transfer function (HRTF) to realistically render spatial audio. The HRTF may be numerically simulated to represent a particular pose of the user that is being rendered. An audio filter based on the HRTF can be applied to an audio input signal to generate an audio output signal. When played by the media system, the audio output signal can recreate spatial audio that accounts for the particular pose of the user and accurately reproduce real life. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a pictorial view of a user positioned relative to a sound source in a soundscape, in accordance with an embodiment. 
         FIG. 2  is a flowchart of a method of reproducing spatial audio based on a head-to-torso orientation, in accordance with an embodiment. 
         FIG. 3  is a schematic view of a method of reproducing spatial audio based on a head-to-torso orientation, in accordance with an embodiment. 
         FIG. 4  is a pictorial view of a head of a user moving relative to a sound source in a soundscape, in accordance with an embodiment. 
         FIG. 5  is a graph of a head and torso orientation based on head orientation data over time, in accordance with an embodiment. 
         FIG. 6  is a graph of a head and torso orientation based on head orientation data over time, in accordance with an embodiment. 
         FIG. 7  is a graph of a head-to-torso orientation based on head orientation data over time, in accordance with an embodiment. 
         FIG. 8  is a pictorial view of various head-to-torso measurements for determining a head-to-torso orientation directly, in accordance with an embodiment. 
         FIG. 9  is a pictorial view of a head above torso mesh generation used to simulate a head-related transfer function for various combinations of head-to-source and head-to-torso orientations, in accordance with an embodiment. 
         FIG. 10  is a block diagram of a media system, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects describe a media system and a method of using the media system to reproduce spatial audio based on a head-to-torso orientation of a user. The media system can include one or more of a mobile device or a head mounted device. For example, the media system can include a pair of headphones having one or more processors to determine the head-to-torso orientation based on head orientation data. In an aspect, the mobile device can be a smartphone and the head mounted device can be circumaural headphones. The mobile device, however, can be another device for rendering or playing audio to the user, such as a desktop computer, a laptop computer, etc., and the head mounted device can include other types of headphones, such as earbuds or a headset, to name only a few possible applications. 
     In various aspects, description is made with reference to the figures. However, certain aspects may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the following description, numerous specific details are set forth, such as specific configurations, dimensions, and processes, in order to provide a thorough understanding of the aspects. In other instances, well-known processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the description. Reference throughout this specification to “one aspect,” “an aspect,” or the like, means that a particular feature, structure, configuration, or characteristic described is included in at least one aspect. Thus, the appearance of the phrase “one aspect,” “an aspect,” or the like, in various places throughout this specification are not necessarily referring to the same aspect. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more aspects. 
     The use of relative terms throughout the description may denote a relative position or direction. For example, “rightward” may indicate a first direction away from a reference point. Similarly, “leftward” may indicate a location in a second direction away from the reference point and opposite to the first direction. Such terms are provided to establish relative frames of reference, however, and are not intended to limit the use or orientation of a media system to a specific configuration described in the various aspects below. 
     In an aspect, a media system is used to reproduce spatial audio based on head-to-torso orientation of a user. The head-to-torso orientation can be determined by measuring the head and torso orientation directly, or alternatively, the head-to-torso orientation can be determined based on head orientation data alone. For example, the media system can include a head tracking device to generate head orientation data for the head of the user, and torso orientation data for the torso of the user can be estimated or inferred from the head orientation data. The head-to-torso orientation data can be used to select an appropriate head-related transfer function (HRTF) that corresponds to the head-to-torso orientation, and a binaural audio filter based on the HRTF can be applied to an audio input signal to generate an audio output signal for playback to the user. The reproduced audio output signal can accurately recreate a spatial audio experience by accounting for head-to-source orientation and head-to-torso orientation. 
     Referring to  FIG. 1 , a pictorial view of a user positioned relative to a sound source in a soundscape is shown in accordance with an embodiment. A media system can provide an accurate spatial audio experience by accounting for both head-to-source orientation and head-to-torso orientation. More particularly, the media system can apply binaural audio filters based on HRTFs that account for relative orientation between a sound source  100  and a head  102  of a user  104 , as well as a relative orientation between head  102  and a torso  106  of the user  104 . 
     Each of sound source  100 , head  102 , and torso  106  can have respective orthogonal axes that provide respective frames of reference. In an embodiment, source axes  108  of sound source  100  defines an absolute frame of reference within a soundscape. More particularly, sound source  100  may have a point location within the soundscape, and thus, relative positions and movements of head  102  and torso  106  may be determined relative to the point location. Accordingly, head axes  110  of head  102  can be aligned with source axes  108 , as shown, or misaligned when the user moves his head from the illustrated position. Similarly, torso axes  112  of torso  106  can be aligned with source axes  108  and head axes  110 , as shown, or misaligned when the user moves his torso from the illustrated position. 
     It will be appreciated that the frame of reference for determining relative positions and movements between the head  102  and torso  106  may be calculated within a separate, inertial reference frame. More particularly, the virtual sound source  100  may move, and thus, it may be more convenient or practical to determine relative positions of the sound source  100 , head  102 , and torso  106  relative to an independent reference datum. Such translations between alternate frames of reference and the source frame are considered to be within the scope of this description. For example, when the positions and orientations of sound source  100 , head  102 , and torso  106  are known relative to the independent reference datum, which may be arbitrarily set within the soundscape, the relative positions and orientations between two or more of the sound source  100 , head  102 , and torso  106  can be calculated. 
     Each of the orthogonal axes can be further defined based on axial subcomponents. A vertical axis of each group of axes may be termed an azimuth axis because the respective object can rotate about the azimuth axis when subtending a yaw angle, e.g., user  104  can turn head  102  rightward through the yaw angle to view something to the side. A laterally-directed axis of each group of axes may be termed an elevation axis because the respective object can rotate about the elevation axis when subtending a pitch angle, e.g., user  104  can tilt head  102  upward through the pitch angle to view something above. A forward-directed axis of each group of axes may be termed a roll axis because the respective object can rotate about the roll axis when subtending a roll angle, e.g., user  104  can crane head  102  sideways to listen to something above him. To accurately account for the relative orientation between sound source  100  and both head  102  and torso  106 , an HRTF can be associated with an angular differential between source axes  108  and head axes  110 , a distance from an origin of source axes  108  to an origin of head axes  110 , an angular differential between head axes  110  and torso axes  112 , and a distance between the origin of head axes  110  and an origin of torso axes  112 . Similarly, an HRTF can be associated with other relative distances/orientations, such as an angular differential between source axes  108  and head axes  110 , a distance from the origin of source axes  108  to the origin of head axes  110 , an angular differential between source axes  108  and torso axes  112 , and a distance between the origin of source axes  108  and the origin of torso axes  112 . In any case, an HRTF that fully describes the relative position and orientation between sound source  100 , head  102 , and torso  106  in the soundscape can be used to accurately render spatial audio. 
     Referring to  FIG. 2 , a flowchart of a method of reproducing spatial audio based on a head-to-torso orientation is shown in accordance with an embodiment. The flowchart of  FIG. 2  is described in detail with respect to the remaining figures, including with respect to the illustrated flowchart of  FIG. 3 . Accordingly, the operations of  FIG. 2  are referenced integrally with the descriptions of  FIGS. 3-10  below. 
     Referring to  FIG. 3 , a schematic view of a method of reproducing spatial audio based on a head-to-torso orientation is shown in accordance with an embodiment. At operation  202 , a head-to-source orientation between head  102  of user  104  and sound source  100  are determined. As described below, a media system used to render spatial audio can include a head tracking device  302  to generate head orientation data  304 . For example, head tracking device  302  can be a portion of a head mounted device  306  having one or more sensors to generate data representing the spatial orientation of head tracking device  302  in space. In an embodiment, head mounted device  306  is an audio capable device worn on head  102  of user  104 , such as a pair of headphones. The headphones can contain one or more accelerometers used to detect or measure a direction of gravity, e.g., relative to the user&#39;s head  102 . Accordingly, the gravity vector can be used to determine a head orientation within space, assuming that user  104  is wearing the headphones in an expected manner, e.g., with the ear cups over the user&#39;s ear and the headband over a top of head  102 . 
     Sound source  100  may be assumed to have source axes  108  arranged in a particular manner with respect to the space. For example, the azimuth axis of source axes  108  may be assumed to be vertical, e.g., aligned with the gravity vector detected by accelerometer(s) of head tracking device  302 . Given that the position and orientation of sound source  100  within space is known via the spatial audio simulation, and the orientation of head  102  within space is known from head orientation data  304 , the relative position and orientation between head  102  and sound source  100  may be calculated. More particularly, at block  308 , one or more processors of the media system can receive source locations  310  describing the position and orientation of sound source  100  in the space, and head orientation data  304  describing the orientation of head  102  within space. The processor(s) can calculate a head-to-source orientation  312  between head  102  and sound source  100  based on the received data. Head-to-source orientation data can include a relative yaw, pitch, or roll angle between source axes  108  and head axes  110 . Furthermore, head-to-source orientation  312  data can include a distance between the origin of source axes  108  and the origin of head axes  110 . Thus, head-to-source orientation data can fully describe the relative position and orientation between sound source  100  and head  102  within the soundscape. 
     At operation  204 , a head-to-torso orientation  314  between head  102  and torso  106  of user  104  can be determined. It will be appreciated that the media system can determine head-to-torso orientation  314  based on direct measurements of the relative position and orientation between head  102  and torso  106  (at block  316 ), or by estimates of the relative position and orientation between head  102  and torso  106  made based on head orientation data  304  received from head tracking device  302  (at block  318 ). Each of these embodiments is described below, beginning with the estimation of head-to-torso orientation  314  from head tracking data alone. Head-to-torso orientation data can include a relative yaw, pitch, or roll angle between head axes  110  and torso axes  112 . Furthermore, head-to-torso orientation data can include a distance, e.g., a three-dimensional vector having an x-, y-, and z-component, between an origin of head axes  110  and origin of torso axes  112 . The angular data can provide a relative orientation and the distance data can provide a relative position between the axes. Thus, head-to-torso orientation data can fully describe the relative position and orientation between head  102  and torso  106  within the soundscape. 
     Referring to  FIG. 4 , a pictorial view of a head of a user moving relative to a sound source in a soundscape is shown in accordance with an embodiment. Unlike existing virtual audio rendering systems, which assume that head  102  is locked to torso  106 , i.e., head axes  110  and torso axes  112  remain aligned whenever head  102  moves, the media system can, at block  318 , make predictions about the relative position and orientation between head  102  and torso  106  (which may include misaligned axes) based only on head orientation data  304 . More particularly, the media system can infer the torso orientation based on expected behavior or expected movements of torso  106  that accompany head movements. 
     In an embodiment, user  104  moves head  102  relative to sound source  100 . For brevity and ease of understanding, the example illustrated in  FIG. 4  shows relative movement by an angle about the azimuth axis of head axes  110 , i.e., through a yaw angle. It will be appreciated that relative movements may also be through a pitch angle or a roll angle. 
     As user  104  moves head  102 , e.g., turning rightward, from an initial orientation  402  toward a final orientation  404 , head  102  subtends the head-to-source yaw angle  406 . Head-to-source yaw angle  406  is defined by head orientation data  304  generated by head tracking device  302 . More particularly, head orientation data  304  can define an angle between a roll axis of head  102  and a roll axis of sound source  100  (which are illustrated as being initially aligned), and thus, head orientation data  304  can define a yaw angle between head  102  and sound source  100 . Head orientation data  304  can be input to a head movement analyzer block  410 . Head movement analyzer can include one or more algorithms implemented by one or more processors of the media system to estimate a relative orientation between torso  106  and sound source  100 . For example, head movement analyzer  410  can infer a torso-to-source yaw angle  412  between torso  106  and sound source  100  based on head orientation data  304 . 
     Torso-to-source yaw angle  412  can define an estimated angle between a roll axis of torso  106  and a roll axis of sound source  100 . The estimated angle may not precisely correspond to an actual relative orientation between torso  106  and sound source  100 , as shown in  FIG. 4 , however, it may more accurately define the relative orientation as compared to not accounting for torso movement at all in existing systems. Certain examples of the algorithms that may be used to infer torso movement are described below, and generally, the estimates can be based on numerical methods implemented on head orientation data  304 , numerical techniques implemented on head orientation data  304  that include conditional boundaries, or matching head orientation data  304  to learned data sets, to infer torso orientation data  420  from the measured head movements. In any case, head movement analyzer  410  can output the estimated torso orientation data  420  describing the expected movement of torso  106 . 
     The media system can use head orientation data  304  and torso orientation data  420  to determine head-to-torso orientation  314 . In an embodiment, head-to-torso orientation  314  is a differential between head orientation data  304  and torso orientation data  420 . When the relative position and orientation between sound source  100  and both head  102  and torso  106  is known, the differential can relate the position and orientation of head  102  and torso  106  to each other. The sound source  100  effectively provides a reference point within the soundscape. For example, when both head  102  and torso  106  have a same relative position and orientation to sound source  100 , the head-to-torso orientation  314  is zero. In such case, the head axes  110  and the torso axes  112  may be considered to be coincident or aligned. 
     The head-to-torso estimation block  318  may utilize algorithms that assume that the long term orientation of head  102  relative to torso  106  is zero. For example, people may tend to look forward relative to their shoulders, and thus, the head-to-torso estimation may infer that head-to-torso orientation  314  trends to zero over time. The estimation therefore allows for short term motions of head  102  to be interpreted as head above torso rotations. If head  102  is rotated for extended periods of time, however, then the media system will interpret the long term movements as whole body rotation by user  104  (torso  106  has rotated along with head  102 ). As described below, the torso movement estimation can be controlled by numerous factors, including time delays, angular thresholds, rates of movement, etc. Each of the torso movement estimations and the determinations of head-to-torso orientation  314  can include determining that torso  106  moves toward alignment with head  102  when head orientation meets a respective head movement condition. 
     Referring to  FIG. 5 , a graph of a head and torso orientation based on head orientation data over time is shown in accordance with an embodiment. The graph can plot source orientation data  502 , head orientation data  304 , and torso orientation data  420 , each as angle versus time information. By way of example, the angle may refer to as a yaw angle of each of sound source  100 , head  102 , and torso  106 . Similar data may be generated, however, for a pitch angle, roll angle, or absolute position of each of the soundscape objects. 
     In an embodiment, torso orientation data  420  is estimated based on a numerical analysis of head orientation data  304 . The numerical analysis can include determining that torso  106  moves toward alignment with head  102  when head orientation data  304  meets a head movement condition  504 . Head movement condition  504  can be a movement of head  102  away from an initial position. For example, the torso orientation may have a value equal to a median or an average of head orientation over time. The numerical technique, e.g., averaging, may occur over a time window, such as a 20 second time window. Accordingly, the torso orientation can have a value equal to an average of head orientation data  304  sampled over a preceding 20 second time window. Similarly, the torso orientation can have a value equal to a median of head orientation data  304  sampled over a preceding 20 second time window. These timeframes are provided by way of example only. 
     The result of the numerical techniques described above is to have torso orientation that moves with head orientation whenever head  102  moves. Torso orientation, however, may lag behind head orientation. As illustrated, user  104  may turn head  102  in a first direction, e.g., rightward, from a zero-degree direction that is aligned to sound source  100 . Subsequently, user  104  may turn head  102  in a second direction, e.g., leftward, crossing through the zero-degree direction. Head  102  may ultimately be turned to a direction that is between the leftmost direction and the zero-degree direction. Concurrently with head movement, the torso orientation can be inferred to move rightward and leftward lagging the head  102 , and eventually, e.g., after the head  102  remains in a same direction for the time window period, the torso  106  may also be directed in the same direction. Essentially, the head tracking data and the inferred torso orientation data  420  describes head-to-torso orientation  314  that diverges from an initially aligned state and then converges to the aligned state again after the head stops moving. 
     Referring to  FIG. 6 , a graph of a head and torso orientation based on head orientation data over time is shown in accordance with an embodiment. The graph can plot source orientation data  502 , head orientation data  304 , and torso orientation data  420 , each as angle versus time information. 
     The estimation of torso orientation may include bounded numerical techniques to infer that torso  106  remains stationary unless a head movement condition  504  occurs in which head  102  has moved to and remained at an orientation for a predetermined length of time. More particularly, the numerical analysis can include determining that torso  106  moves toward alignment with head  102  when head orientation data  304  meets a head movement condition  504 . Head movement condition  504  can include movement of head  102  from a first head orientation  602  to a second head orientation  604 , and then resting head  102  at the second orientation for a predetermined period of time  606 . 
     Head  102  can move from first head orientation  602  to second head orientation  604  by turning leftward and then rightward until the user  104  is facing a direction other than the zero-degree direction of sound source  100 . During this movement, torso orientation may be estimated as remaining stationary and facing the zero-degree direction that head  102  initially faced. When head  102  arrives at second orientation from first orientation, head  102  may remain fixed or at rest within a degree of motion. More particularly, head  102  may not vary from second orientation by more than a predetermined angular tolerance. When head  102  remains at rest for the predetermined period of time  606 , e.g., 30 seconds, head movement analyzer  410  can determine that user  104  is likely to have moved torso  106  toward head  102  so as to avoid maintaining a turned head  102  for an extended period of time. In response, torso orientation data  420  can indicate that torso  106  moves toward head  102  when head movement condition  504  occurs. 
     Torso orientation data  420  can indicate that torso  106  moves toward alignment with head  102  in a predetermined manner. As shown, a linear ramp rate may be used to transition torso  106  orientation from the zero-degree direction to the second orientation (the direction of second head orientation  604 ). The ramp rate may be chosen to gradually adjust acoustic effects from the turning torso  106  and avoid disturbingly abrupt changes. Other transition rates, such as non-linear and/or stepped change rates may also be used. Essentially, the head tracking data  304  and the inferred torso orientation data  420  describes head-to-torso orientation  314  that diverges from an initially aligned state and then converges to the aligned state again after the head stops moving. 
     Referring to  FIG. 7 , a graph of a head-to-torso orientation based on head orientation data over time is shown in accordance with an embodiment. The graph can plot source orientation data  502 , head orientation data  304 , and torso orientation data  420 , each as angle versus time information. 
     The estimation of torso orientation may include determining that torso  106  moves toward alignment with head  102  when head orientation data  304  meets a head movement condition  504 . Head movement condition  504  can include movement of head  102  by a predetermined angle  702 . For example, predetermined angle  702  can be a yaw angle through which head turns, although it will be appreciated that predetermined angle  702  may include one or more of a pitch angle (head  102  nodding upward or downward) or a roll angle (head  102  craning toward a right shoulder or a left shoulder). The estimation may assume that torso  106  remains stationary unless head  102  is turned by an amount that is unusual or impossible. By way of example, humans cannot turn their heads by more than 90 degrees relative to their torso  106 , and thus, predetermined angle  702  to trigger torso movement in the torso orientation estimates may be 90 degrees. 
     Head  102  can move from the zero-degree direction aligned with sound source  100  leftward and rightward until the user is facing a direction other than the zero degree direction of sound source  100 . When head  102  is turned by predetermined angle  702 , head movement condition  504  occurs. Accordingly, torso orientation can be inferred to turn in the direction of head  102  to maintain a maximum angular differential, e.g., a head-to-torso orientation  314  of 90 degrees or less. When head  102  stops moving and rests at the new orientation in which head  102  faces the non-zero direction, torso  106  may continue to move toward alignment with head  102 . For example, torso  106  can turn according to a linear ramp rate to transition torso  106  into alignment with head  102 . Other transition profiles, such as non-linear and/or stepped transitions may be used. Essentially, the algorithm can assume that the long term estimate of head-to-torso orientation  314  is zero, and the head tracking data  304  and the inferred torso orientation data  420  describes head-to-torso orientation  314  that diverges from an initially aligned state and then converges to the aligned state again after the head stops moving. 
     It will be appreciated that the above-described algorithms for inferring torso orientation data  420  (and hence head-to-torso orientation  314 ) are intended as examples and shall not be considered to be restrictive. For example, although the examples are described with respect to changes in yaw angle, similar algorithms may be used to infer pitch angle and/or roll angles of torso axes  112  relative to head  102  or sound source  100 . In such cases, different algorithms may be employed. For example, with respect to the numerical technique described with respect to  FIG. 5 , estimating torso orientation in the pitch direction may include averaging head movements over a longer period of time. The inference may be based on the assumption that user  104  is typically in an upright position, and thus, when head orientation data  304  indicates that head  102  is tilting backward, it is more likely that user  104  is looking at the ceiling rather than lying down on a bed. Accordingly, torso orientation may not begin to tilt backward unless head  102  is positioned in the backward tilted orientation for a relatively long period of time. Similarly, a predetermined period of time  606 , as described with respect to  FIG. 6 , may be used to maintain torso orientation in an upright and stationary position unless head  102  is tilted backward for a relatively long period of time. Accordingly, the time constants, transition rates, etc., may differ based on whether an inference is being made about the yaw angle, pitch angle, roll angle, or position of torso  106 . 
     The algorithms used by head movement analyzer  410  to infer torso orientation may be adapted to various conditions. More particularly, determining head-to-torso orientation  314  may be based on contextual information that is available to the media system. The contextual information can be about one or more of a current state of user  104  or a current use of head tracking device  302 . Depending on the current state or the current use, the inference technique can be adjusted. 
     In an embodiment, the contextual information that drives the mode of inference indicates whether the user  104  is ambulatory. For example, accelerometer data from head tracking device  302  can detect that user  104  is standing or sitting upright, walking, running, or otherwise in an ambulatory position. Based on the contextual information, a head-to-torso orientation may be inferred to include head  102  relative to a vertically-oriented torso  106 . For example, if the media system detects that user  104  is walking, then rotations of torso  106  are more likely to occur concurrently with rotations of head  102 , e.g., torso  106  probably rotates simultaneously with head  102 . Accordingly, torso orientation may be inferred to have a same orientation as head  102  orientation. This is the same as stating that torso orientation data  420  is equal to an average of head orientation data  304  taken over a single or relatively few samples (and therefore an adaptation of the technique described with respect to  FIG. 5 .) 
     The contextual information may indicate that head tracking device  302  is being used in a particular scenario. For example, head tracking device  302  may be used to play audio content of a movie to user  104 . The contextual information may be provided by headphones or a mobile device that identifies the audio as a movie soundtrack. If the media system detects that user  104  is watching a movie, then the directions of head  102  and torso  106  may be locked to each other. For example, it may be assumed that someone is usually immobile while watching movies. 
     Accordingly, when head tracking device  302  or a companion device determines that user  104  is watching the movie, head-to-torso orientation  314  may be inferred to include head  102  aligned to torso  106 . That is, head-to-torso orientation  314  may be zero in one or more of the yaw, pitch, or roll directions. This example is non-restrictive, however, because it may be that people usually sit to watch movies with their torso  106  still and their head  102  moving occasionally above their torso  106 . Accordingly, when head tracking device  302  or a companion device determines that user  104  is watching the movie, head-to-torso orientation  314  may be inferred to include head  102  free to move relative to torso  106  in one or more directions, e.g., the yaw direction. The head-to-torso orientation  314  may be zero in one or more other directions, however, such as the pitch direction. It will be appreciated from the above that the particular head-to-torso orientation inferences can be drawn from contextual information describing predetermined scenarios that are associated with expected use patterns. 
     Other more simplistic or complex inferences may be made to determine head-to-torso orientation  314 . For example, the media system can estimate torso orientation data  420  as remaining stationary regardless of an amount or a time that head  102  has moved out of alignment with torso  106 . As described above, existing systems do not account at all for the likelihood that head  102  and torso  106  move separately from each other in most situations. Accordingly, the inference that head  102  is above torso  106  and only head  102  is moving (torso  106  remains stationary) can be an improvement over the state-of-the-art. 
     In an embodiment, the algorithms used to infer torso orientation may include machine learning algorithms that employ predictive analytics to determine head-to-torso orientation  314  based on head orientation data  304 . In the context of the algorithms described above, the head movement condition  504  that triggers movement of torso  106  can include a match between the measured head movement and a pattern of head movement of one or more other users  104 . Data sets that measure or infer head-to-torso movements of users in particular scenarios can be stored and mined to determine the patterns of head movement of a population. As a non-limiting example, measured head and/or torso orientation data sets can show that when users heads are bobbing up and down in the pattern of a runner&#39;s cadence, then the torso of the users will typically twist back and forth as the users pump their arms while running. Accordingly, when the media system identifies the bobbing motion in head orientation data  304  generated by head tracking device  302 , torso orientation data  420  may be estimated as having the twisting motion to ensure that spatialized sound accurately reproduces the reflections that occur from the torso  106  while user  104  runs. Other examples that learn from patterns of movement of a group of people and use the learned information to infer the relative position between head  102  and torso  106  are contemplated as being within the scope of this description. 
     Referring again to  FIG. 3 , head-to-torso orientation  314  may be directly measured at block  316 . The relative position or orientation between head  102  and torso  106  can be calculated based on a comparison between head orientation data  304  measured by head tracking device  302  and measured torso orientation data  324  measured by a torso tracker  320 . A non-restrictive example follows. 
     Referring to  FIG. 8 , a pictorial view of various head-to-torso measurements for determining a head-to-torso orientation directly is shown in accordance with an embodiment. Head orientation data  304  can be captured in a manner similar to that described above. For example, head tracking device  302  can include a set of accelerometers used to detect a direction of gravity relative to head orientation. Head orientation data  304  therefore provides information about a relative position and orientation between head  102  and sound source  100   
     Torso orientation data  324  may be measured by one or more sensors of head mounted device  306  and/or a companion device, such as a mobile device  802 . The sensor(s) can generate torso orientation data  324  that describes a position and/or orientation of torso  106  in space. In an embodiment, the sensor(s) include a downward looking camera  804 . Downward looking camera  804  can identify and track a visual feature, e.g., a pattern of the user&#39;s clothing, to determine movement of head  102  relative to torso  106 . Alternatively, the sensor can be a time of flight sensor or a depth sensor used to infer movement of head  102  relative to torso  106 . Wearable sensors may also be used to detect torso orientation. For example, user  104  may wear accelerometers on torso  106 , such as accelerometers embedded within mobile device  802 , and thus, the accelerometers can detect movement of torso  106 . In an embodiment, mobile device  802  includes a sensor such as a forward facing camera  806  to measure orientation of torso  106 . Forward facing camera  806  can capture gross dimensions of torso  106 , and thus, the dimensional data can be analyzed to infer movement of torso  106 . Accordingly, numerous techniques exist to allow direct measurement of torso orientation. The one or more processors of the media system can receive the measured torso orientation data  420  and use the data to calculate head-to-torso orientation  314 . Accordingly, estimated or measured head-to-torso orientation  314  can be used to drive selection of an appropriate HRTF for spatial audio reproduction. 
     Referring again to  FIG. 3 , the media system, at operation  206 , applies a binaural audio filter, via binaural filtering at block  330 , to an audio input signal  332  to generate an audio output signal  334  that accurately represents the soundscape. Audio input signal  332  can be associated with sound source  100 . The audio input signal  332  can be a signal representing sound of a scene captured at the point location of the sound source  100  within the soundscape. For example, the audio input signal  332  may be captured by array(s) of microphones in free space within the soundscape, e.g., at or near the point location. The microphone array(s) record the sound of the scene, and the recording is represented by the audio input signal  332 . The binaural audio filter applied at block  330  is based on an HRTF that corresponds to both head-to-source orientation  312  and head-to-torso orientation  314 . Accordingly, the media system can re-create a high-quality virtual audio demonstration that accounts for the correct positioning of torso  106  using head-to-source and head-to-torso tracking. 
     Measuring HRTF sets for all possible relative positions and orientations between sound source  100 , head  102 , and torso  106  can be time-consuming. Accordingly, typical techniques of generating HRTFs in a laboratory may not be well-suited to establishing an HRTF data set that can support the method described above. More particularly, measuring HRTFs for every combination of head-to-body orientation and source-to-head orientation may be prohibitive. Therefore, in an embodiment, HRTFs for different head-to-source and head-to-torso orientations of user  104  may be numerically simulated. Numerical simulation of the HRTFs does not require user  104  to be measured for extensive periods of time, as is required in the laboratory setting. 
     Referring to  FIG. 9 , a pictorial view of a head above torso mesh generation used to simulate a head-related transfer function for various combinations of head-to-source and head-to-torso orientations is shown in accordance with an embodiment. In an embodiment, numerically simulated HRTFs are calculated for different relative orientations between head  102  and torso  106 . It has been shown that the HRTF of an individual can be accurately simulated using numerical acoustic simulation codes, such as the finite element method or boundary element method of calculating HRTFs. A mesh of head  102  (head mesh  902 ) and a mesh of torso  106  (torso mesh  904 ) can be generated using known imaging techniques, such as 3D optical scanning. Head mesh  902  and torso mesh  904  can be combined into a head-and-torso mesh  906  having head  102  positioned and oriented in a respective manner relative to torso  106 . Head mesh  902  and torso mesh  904 , which are imaged separately, can be stitched together into a variety of different head-and-torso meshes  906 . Each head-and-torso mesh  906  can represent a particular head-to-torso orientation  314 . Accordingly, each head-and-torso mesh  906  can correspond to a particular HRTF simulation. 
     In an embodiment, the set of HRTFs corresponding to respective head-to-torso geometries can be simulated for different head-to-sound source orientations. More particularly, the family of head-to-torso geometries can be used to calculate HRTFs for the full set of head-to-source and head-to-torso orientations. It will be appreciated that each HRTF is frequency dependent, i.e., each HRTF is dependent on a frequency band of the virtual sound emitted by sound source  100 . Accordingly, the simulated HRTFs can populate HRTF database  350  such that HRTF database  350  ( FIG. 3 ) includes several numerically simulated HRTFs  352  for respective combinations of head-to-source orientations  312  and head-to-torso orientations  314 . Each HRTF in HRTF database  350  can correspond to a permutation of a yaw angle between sound source  100  and head  102 , a pitch angle between sound source  100  and head  102 , a distance between sound source  100  and head  102 , a yaw angle between head  102  and torso  106 , a pitch angle between head  102  and torso  106 , a distance between head  102  and torso  106 , and a frequency of the emitted virtual sound. Each HRTF  352  is therefore appropriate for simulating the soundscape of a user having a particular pose. 
     The media system can select, from HRTF database  350 , the appropriate HRTF based on head-to-source orientation  312  and head-to-torso orientation  314 , which is measured or estimated as described above. Accordingly, an appropriate binaural audio filter based on the selected HRTF can be applied to audio input signal  332  to generate audio output signal  334 . Audio output signal  334  can be a binaural signal that is sent to head mounted device  306 , e.g., headphones. At operation  208 , audio output signal  334  is played by the media system to recreate spatial audio. For example, the processor provides a left audio output signal and a right audio output signal (generated by binaural filters, respectively) to drive respective speaker drivers of a headset (headphones), which recreates the spatial sound emitted by the sound source  100  as would be heard by the user  104  if the user were present in the sound field of the sound source  100 . The spatial audio can include sound source  100  at the relative position and location from user  104 . More particularly, the spatial audio reproduction can include sounds emitted to user  104  by sound source  100 , and can accurately reproduce the effects of the head orientation and the torso orientation on the perceived sounds. 
     Storing the multitude of HRTFs that represent every possible head-to-source and head-to-torso orientations can be memory intensive. In an aspect, the memory demands associated with storing a large number of HRTFs can be addressed by storing a smaller set of HRTFs, along with accompanying correction filters that compensate for related head-to-torso orientations. More particularly, for each HRTF corresponding to a particular head-to-source orientation, the HRTF database  350  may include one or more correction filters that compensate for audio effects of respective head-to-torso orientations at the particular head-to-source orientation. By way of example, an HRTF corresponding to a source being directly in front of a listener may be associated with a first correction filter that adjusts for a first relative position between the head and the torso, a second correction filter that adjusts for a second relative position between the head and the torso, etc. To accurately simulate the soundscape, a binaural audio filter based on the nominal HRTF for a given head-to-source orientation can be selected. The binaural audio filter may be combined with the particular correction filter for the head-to-torso orientation that exists concurrently with the head-to-source orientation. The combined audio filter may then be applied to the audio input signal to generate the audio output signal that simulates the soundscape. 
     Referring to  FIG. 10 , a block diagram of a media system is shown in accordance with an embodiment. A media system  1000  can include mobile device  802 , which can be any of several types of portable devices or apparatuses with circuitry suited to specific functionality. Similarly, media system  1000  can include head mounted device  306 , e.g., headphones, which can be any of several types of head-mounted audio devices or apparatuses with circuitry suited to specific functionality. Accordingly, the diagrammed circuitry is provided by way of example and not limitation. 
     Mobile device  802  may include one or more device processors  1002  to execute instructions to carry out the different functions and capabilities described above. Similarly, head mounted device  306  can include one or more headphones processors  1004  to execute instructions to carry out the different functions and capabilities described above. Instructions executed by device processor(s)  1002  and/or headphones processor(s)  1004  may be retrieved from respective memory, e.g., a device memory  1006  or a headphones memory  1008 , which may include a non-transitory computer readable medium. For example, the instructions may be in the form of an operating system program having device drivers and/or an audio rendering engine for rendering music playback, binaural audio playback, etc., according to the methods described above. Device processor(s)  1002  and/or headphones processor(s)  1004  can retrieve data from respective memory for various uses. 
     In an aspect, device processor(s)  1004  can access and retrieve audio data stored in device memory  1006 . Audio data may be an audio input signal  332  provided by one or more audio sources  1010 . Audio sources  1010  can include phone and/or music playback functions controlled by telephony or audio application programs that run on top of the operating system. In an aspect, an audio application program can generate predetermined audio signals, e.g. soundscape signals, to be played by device speaker  1012  and/or headphones speaker  1062 . Similarly, audio sources  1010  can include an augmented reality (AR) or virtual reality (VR) application program that runs on top of the operating system. In an aspect, an AR application program can generate a spatial input signal  332  to be output to headphones  306 . For example, mobile device  802  and headphones  306  can communicate signals wirelessly via respective RF circuitry, or through a wired connection. Accordingly, headphones  306  can play spatial audio to user  104  based on spatial input signal  332  from audio sources  1010 . 
     In an aspect, device memory  1006  stores audio filter data for use by device processor(s)  1002 . For example, device memory  1006  can store HRTF database  350 . HRTF database  350  can include numerically simulated HRTFs  352  corresponding to respective combinations of head-to-source orientation  312  and head-to-torso orientation  314  (and being frequency dependent). The dataset of HRTFs encapsulate the fundamentals of spatial hearing of user  104 . Accordingly, device processor(s)  1002  can use HRTF database  350  to select an appropriate HRTF and apply the HRTF to audio input signal  332  to generate audio output signal  334  corresponding to the sound source  100 , head  102 , and torso  106  relative positions and orientations. 
     Device memory  1006  can also store data generated by an imaging system of mobile device  802 . For example, an optical scanner such as a structured light scanner (or RGB camera)  1020  of mobile device  802  can capture images of user  104  while mobile device  802  is moved around head  102 , and the images can be stored in device memory  1006 . Images may be accessed and processed by device processor(s)  1002  to determine the head mesh  902  and/or torso mesh  904 . The meshes can be stitched together in different relative orientations to simulate the head-and-torso meshes  906  that are used to simulate HRTFs for user  104 . 
     In an aspect, mobile device  802  can include other sensors to facilitate head or torso tracking of user  104 . For example, forward facing camera  806  of mobile device  802  can capture torso orientation data  420 . Similarly, an inertial measurement unit (IMU)  1050  can be used to generate torso orientation data  420  when mobile device  802  is worn by user  104 . 
     To perform the various functions, device processor(s)  1002  may directly or indirectly implement control loops and receive input signals from, and/or provide output signals to, other electronic components. For example, device processor(s)  1002  may receive input signals from microphone(s) or menu buttons of mobile device  802 , including through input selections of user interface elements displayed on a display. 
     Headphones  306  can include one or more earphone  1060 , e.g., a pair of earphones connected by a headband, a neck cord, or another physical connector (shown in phantom). In an aspect, headphones  306  are insert-type earphones. As described above, headphones  306  may include one or more headphones processors  1004  to execute instructions and to carry out the different functions and capabilities described above. The instructions may be in the form of an operating system program having device drivers and/or an audio rendering engine for rendering music playback, binaural audio playback, etc., according to the methods described above. 
     In an aspect, headphones memory  1008  stores audio data, e.g., a cached portion of audio input signal  332  received from mobile device  802 . Headphones memory  1008  can similarly store music or AR/VR applications, like device memory  1006 . In an embodiment, headphones memory  1008  store HRTF database  350 . Headphones processor  1004  can receive audio input signal  332  from mobile device  802  or headphones memory  1008 , select the appropriate HRTF  352  based on the head-to-source and head-to-torso orientation information, and apply the selected HRTF filter to the cached portion when providing binaural playback to user  104  through headphones  306 . In an aspect, all functionality of system  100  can be performed by the components in headphones  306 . 
     In an aspect, headphones  306  can include sensors to facilitate head tracking and/or torso tracking of user  104 . For example, headphones  306  can incorporate a camera, a depth sensor, or an IMU  1050  to generate data corresponding to a relative orientation between headphones  306  and a gravity vector or a relative orientation between headphones  306  and torso  106 . This head tracker and torso tracker data can be provided to headphones processor(s)  1004  to determine and/or estimate head-to-source and head-to-torso orientation, as described above. 
     Each earphone  1060  of headphones  306  can include an earphone speaker  1062  to output a sound to user  104 . More particularly, earphone speakers  1062  can receive audio output signal  334  from device processor  1002  and/or headphones processor  1004 . The audio output signal  334  can drive earphone speakers  1062  to generate and emit spatialized sound toward the ears of user  104 , and therefore, to recreate spatial audio to user  104 . 
     As described above, one aspect of the present technology is the gathering and use of data available from various sources to provide spatial audio. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, TWITTER ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., audiograms, vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to provide spatial audio. Accordingly, use of such personal information data enables users to have an improved audio listening experience. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide insights into a user&#39;s general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates aspects in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of spatial audio, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed aspects, the present disclosure also contemplates that the various aspects can also be implemented without the need for accessing such personal information data. That is, the various aspects of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, the enrollment process can be performed based on non-personal information data or a bare minimum amount of personal information, such as a height or a weight of the user, other non-personal information available to the device processors, or publicly available information. 
     To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims or claim elements to invoke 35 U.S.C. 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim. 
     In the foregoing specification, the invention has been described with reference to specific exemplary aspects thereof. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.

Metadata:
Filing Date: 20200916
Publication Date: 20220628
Grant Date: 20220628
Priority Date: 20190920
Inventors: Vanne, Antti J.
SATONGAR, Darius A.
VANDYKE, James W.
MERIMAA, JUHA O.
JOHNSON, MARTIN E.
Huttunen, Tomi A.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04S7/304", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04S7/302", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04S2420/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R5/033", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/033", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04S2420/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/017", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04S7/304", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/012", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04S7/304", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R5/033", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04S2420/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/012", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/017", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 82320333