Patent Description:
Today's mobile phones are often used for music playout from online services including YouTube, Spotify, Soundcloud, etc. Some companies, including Apple and Google, have introduced home speakers that can be controlled wirelessly using smartphone applications.

When multiple speakers become available for audio playout in a room, it becomes important to synchronize the audio, e.g., music, playout to provide a desirable soundfield. One example is Sonos' AmpMe which allows several mobile devices (smartphones, tablets,. ) to join a synched group that enables synchronized streaming of music, e.g., from Spotify. The AmpMe app allows a "host" to synchronize playout of music with friends' mobile devices. The host can play music from SoundCloud, YouTube, Spotify, or a local library. Instead of relying on Bluetooth or Wi-Fi technology to connect devices together, AmpMe uses a server centric proprietary audio fingerprinting technology for synchronization and works with a cellular data plan, Wi-Fi network or personal hotspot. When the host selects the "play" button, friends will automatically see the nearby party and can select "join" to auto-sync their devices, thereby creating a synchronized group of devices for playing the music of their choice.

Chromecast Audio similarly allows multiple devices to be joined together into an audio group so they all play the same music selection irrespective of their location.

A potential problem with existing solutions is that known sound systems, when operationally capable, require manual tuning by a trained or otherwise properly coached human operator to establish a proper stereo or multi-channel soundfield for a particular spatial arrangement of sound speakers and the geometry of the targeted room/area for listening.

Some embodiments disclosed herein are directed to a mobile electronic device operating with other mobile electronic devices forming a group for coordinated playout of audio media content. The mobile electronic device includes a wireless network interface circuit, microphone, speaker, a processor, and a memory. The wireless network interface circuit is configured for communication with the other mobile electronic devices through a wireless communication link. The processor operationally connects the microphone, the speaker, and the wireless network interface circuit. The memory stores program code that is executed by the processor to perform operations. The operations include determining a common time sync shared with the other mobile electronic devices, and determining a timing of occurrence of a sound transient that is sensed by the microphone relative to the common time sync. The operations receive timing reports from the other mobile electronic devices, where each of the timing reports indicates a timing of occurrence of the sound transient sensed by a microphone of a respective one of the other mobile electronic devices relative to the common time sync. The sound transient sensed by the mobile electronic devices is generated at a preferred listening location. The operations coordinate timing of playout of audio media content by the group of mobile electronic devices responsive to comparison of the timing of occurrence of the sound transient sensed by the microphone of the mobile electronic device and the timing of occurrences indicated by the timing reports.

A potential advantage of these operations is that a more optimally configured soundfield can be created at any preferred listening location where the sound transient is generated. These operations can be performed without requiring manual tuning by a human operator and without necessitating use of specialized hardware. Moreover, these operations can dynamically adapt the soundfield for observed variations over time in the spatial arrangement of the mobile electronic devices relative to the preferred listening location, the number of mobile electronic devices in a playout group, and/or acoustic effects of the listening room or area.

Some other embodiments disclosed herein are directed to an audio server for coordinated playout of audio media content through a group of mobile electronic devices. The audio server includes a network interface circuit, a processor, and a memory. The network interface circuit is configured for communication with the mobile electronic devices.

The US patent application <CIT> describes an audio reproduction system including a plurality of mobile devices, such as mobiles phones. A processor is configured for executing instructions for prompting the plurality of mobile devices to each output at least a portion of an audio data file to the loudspeaker of the mobile device for achieving contemporaneous play of the audio data file by the plurality of mobile devices.

The US patent <CIT> describes systems and methods wherein wireless communication devices form a wireless network in which music, for example, can be played on the speakers of the wireless communication devices to reproduce surround sound effects from a selected audio source. As the wireless communication devices roam with respect to each other or with respect to a focal point or listening position of the wireless network, the wireless network adjusts how the audio source is played at each speaker of the respective wireless communication device to maintain or to enhance the reproduction of surround sound effects from the audio source.

The US patent <CIT> discloses a method and apparatus for synchronizing media content emitted from various sources. Arrival timing of outputs from the various sources to a particular location is determined and adjusted to reduce synchronization delays at the particular location. Synchronization delays may be determined by detecting the media output from a combination of sources arriving at the location. Control messages are generated by processing the detected output and determining delays to be applied to corresponding sources.

The US patent application <CIT> discloses a mobile terminal that can select among a plurality of subcomponents of a song that are to be played from the terminal in response to communications with another terminal which may concurrently play a different subcomponent of the same song.

The processor is operationally connected to the network interface circuit. The memory stores program code that is executed by the processor to perform operations. The operations include receiving timing reports from the mobile electronic devices. Each of the timing reports indicates a timing of occurrence of a sound transient sensed by a microphone of a respective one of the mobile electronic devices relative to a common time sync shared among the mobile electronic devices. The sound transient sensed by the mobile electronic devices is generated at a preferred listening location. The operations control timing of play out of audio media content by the group of mobile electronic devices responsive to comparison of the timing of occurrences indicated by the timing reports.

Other mobile electronic devices, audio servers, and corresponding methods will be or become apparent to one with skill in the art upon review of the following drawings and detailed description. It is intended that all such additional mobile electronic devices, audio servers and methods be included within this description, be within the scope of the present inventive subject matter, and be protected by the accompanying claims.

Aspects of the present disclosure are illustrated by way of example and are not limited by the accompanying drawings. In the drawings:.

Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of various present inventive concepts to those skilled in the art.

Some embodiments are directed to methods and operations by mobile electronic device and audio server to provide a desired stereo soundfield for a particular spatial arrangement of sound speakers and the geometry of the acoustic effects of the targeted room/area. These methods and operations can be performed using existing hardware of the playout group to determine the room's reverberation and echo characteristics and to calculate therefrom the reverse audio propagation channel needed to aim an optimized stereo, or multi-channel, soundfield to a preferred listing location in the room. These approaches do not require the use of additional and dedicated hardware, which in turn would increase cost of deployment.

There are no previously known approaches where audio playout functionality of mobile electronic devices is analyzed and controlled to synchronize their playout to achieve a stereo image for a designated spatial location while operationally compensating for scenarios when one or more does not remain non-stationary and/or emerges to join the playout group or ceases being available to participate in the playout group.

If playout of media by the mobile electronic devices is not coordinated to form an optimized stereo or other multi-channel soundfield, the resulting sound effect to a listener can be undesirable with audio distortion being introduced to the listener from the out-of-synch arrival and additive effects of the individual audio waveforms at the listening location, stemming from uncorrected phase differences, and distortion introduced into the individual audio waveforms along their pathways to the listener.

Various embodiments of the present disclosure are directed to operations and methods that synchronize audio content playout through a group of mobile electronic devices based on using measurements by the mobile electronic devices of a sound transient and reverse sounding positioning techniques.

For sound propagating in air, the principle of time-reversal or reciprocity applies. This means, given a solution to the acoustic wave equation, then the time reversal (using a negative time) of that solution is also a solution.

This means mobile electronic devices can be operated to record audio which is transmitted in one direction, which recorded audio reflects characteristics of the audio channel which change the transmitted audio, relying on the operational assumption of reciprocity, i.e., that the same changes that have happened to the audio transmitted in one direction will also happen when transmitting audio in the opposite direction. Operations according to various embodiments disclosed herein use reciprocity to coordinate and control the playout of audio content by a group of mobile electronic devices based on the transmission effects that these mobile electronic devices sense in a sound transient that is generated at a preferred listening location. These operations are extendable to environments having any number of mobile electronic devices as audio playout sources.

Various embodiments of the present disclosure use speakers from any number of mobile electronic devices (mobile phones, tablet computers, media players, networked loudspeakers, etc.) to create a more optimized soundfield for a specific listener at a preferred listening location. For brevity and without limitation, a "mobile electronic device" is also referred to as a "mobile device" and "device.

Properly synchronizing the playout of media by the mobile electronic devices can create a soundfield with improved stereo or other multi-channel audio image which can provide a more enjoyable and better sounding music (or other audio media playout) experience. Various present embodiments do not require dedicated sounding hardware and can provide an easy-setup that can coordinate playout from any size group of mobile electronic devices to optimize the quality of the soundfield that is created at a preferred listening location.

<FIG> illustrates a system that can operate to coordinate timing of playout of audio media content by a group of mobile electronic devices <NUM> in accordance with various embodiments.

Referring to <FIG>, the mobile electronic devices <NUM> are communicatively interconnected through a wireless communication link, such as a low latency protocol link (e.g., a device-to-device protocol or LTE side-link). A person who is located at a preferred listening location <NUM> can generate a sound transient by, for example, a hand-clap, table knock, providing a transient audio signal through a speaker of one of the mobile electronic devices <NUM>, etc. Each of the mobile electronic devices <NUM> can be configured to determine a timing of occurrence of when the sound transient is sensed by a microphone of the mobile electronic device <NUM>. Timing of playout of audio media content by the group of mobile electronic devices <NUM> is determined on a device-by-device basis responsive to comparison of the respective timing of occurrence of the sound transients determined by the respective mobile electronic devices. A more optimized stereo or multi-channel soundfield can thereby be generated at the preferred listening location.

The audio media content may be a song, sound track accompanying a video, an audiobook, or any other digital audio that can be played by a mobile electronic device through a speaker. The audio media content may be provided by an audio server <NUM> through a radio access network <NUM> and a landline network <NUM> (e.g., Internet). The audio server <NUM> may be a fileserver (e.g., Apple iTunes) that provides audio media content files to client applications hosted on the various mobile electronic devices <NUM> and/or may be an audio streaming service (e.g., Spotify, SoundCloud, Apple Music, or YouTube) that streams audio media content to the various mobile electronic devices <NUM>. As will be explained in further detail below, one of the mobile electronic devices <NUM> may operate as a master that receives and relays the audio media content file and/or streams audio media content to the other mobile electronic devices <NUM>.

In some embodiments, one of the mobile electronic devices <NUM> in the group can operate as a master that controls timing of play out of the audio media content by the other mobile electronic devices in the group. In some other embodiments, an audio server <NUM> (e.g., audio streaming server such as Spotify, YouTube, etc.) operates as the master to control timing of play out of the audio media content by the mobile electronic devices in the group. The master can control playout timing relative to a common time sync used by all of the mobile electronic devices in the group. The common time synch may be defined based on signaling from a Network Time Protocol (NTP) server, a received radio network timestamp or other timing signal, a satellite positioning system (e.g., GPS, GNSS, etc.) timestamp or other timing signal, or by other operations.

The master may stream the audio media content to the mobile electronic devices and/or generate parameters that are used by the mobile electronic devices to process (e.g., filter) the audio media content for playout. The master may generate the parameters to separately control processing by the various mobile electronic devices in ways that adjust for the relative positions of the mobile electronic devices relative to the preferred listening location to create a more optimized stereo soundfield at the preferred listening location. The master can control the timing of playout and/or determine the parameters to be used by the mobile electronic devices based on calculations of the reverse audio propagation channel needed to generate a more optimized stereo soundfield at the preferred listening location and/or based on calculations of audio characteristics (e.g., reverb, echo, etc.) of the room and positioning of the mobile electronic devices, which may be determined based on measurements of magnitude over time of the sound transient sensed by the mobile electronic devices.

<FIG> is a flowchart of operations that may be performed by a mobile electronic device <NUM> that operates with other mobile electronic devices forming a group for coordinated playout of audio media content, in accordance with some embodiments. <FIG> is a block diagram of components of a mobile electronic device <NUM> which are configured to operate in accordance with some embodiments.

Referring initially to <FIG>, the mobile electronic device <NUM> can include: a wireless network interface circuit <NUM> configured for communication with the other mobile electronic devices through a wireless communication link, either directly or via radio access network <NUM>; a microphone <NUM>; a speaker <NUM>; a processor <NUM> operationally connected to the microphone <NUM>, the speaker <NUM>, and the wireless network interface circuit <NUM>; and a memory <NUM> storing program code <NUM> that is executed by the processor <NUM> to perform operations.

Referring now to <FIG>, the operations can include determining <NUM> a common time sync shared with the other mobile electronic devices. The common time sync may be determined based on signaling from a NTP server or by other techniques as explained above. The operations determine <NUM> a timing of occurrence of a sound transient that is sensed by the microphone <NUM> relative to the common time sync. The operations receive <NUM> timing reports from the other mobile electronic devices <NUM>. Each of the timing reports indicates a timing of occurrence of the sound transient sensed by a microphone <NUM> of a respective one of the other mobile electronic devices <NUM> relative to the common time sync. The sound transient sensed by the mobile electronic devices <NUM> is generated at a preferred listening location (e.g., <NUM> in <FIG>). The operations then coordinate <NUM> timing of playout of audio media content by the group of mobile electronic devices <NUM> responsive to comparison of the timing of occurrence of the sound transient sensed by the microphone <NUM> of the mobile electronic device <NUM> and the timing of occurrences indicated by the timing reports.

The operation to coordinate <NUM> timing of playout of audio media content may include controlling when individual ones of the mobile electronic devices <NUM> begin playing from a common location within the audio media content, which may thereby maintain constant timing offsets between where within the audio media content the mobile electronic devices <NUM> are playing through their respective speakers <NUM>. The common location from where the mobile electronic devices <NUM> begin playing may correspond to, for example, the start of a song or from another defined location within the song (e.g., a defined playback time location relative to the start of the song). The timing offsets can be controlled in-part to compensate for differences in the sound propagation times from the various mobile electronic devices <NUM> to the preferred listening location <NUM>. As an alternative, the operation to coordinate <NUM> timing of playout of audio media content may include controlling a relative time shift between audio played out by individual ones of the mobile electronic devices <NUM>. The time shift of each individual mobile electronic device <NUM> relative to another device reflects the difference in respective distance between the two devices and the preferred listening location <NUM>. In practice, they correspond to the time differences between sound propagation times from the preferred listening location <NUM>, where the sound transient was generated, to the mobile electronic devices <NUM> in the group, as is explained further below.

As explained above, one of the mobile electronic devices <NUM> can operate as a master device to coordinate timing of play out of the music/other audio media content. The master may be responsible for distributing music or other audio media content to the other mobile electronic devices <NUM>. For example, users may place their mobile electronic devices in their preferred listening locations within a room. The users each run an audio playout application on their mobile electronic devices, where the application is configured for playing music from locally stored music files or from a music stream that is received from another mobile electronic device and/or from the audio server <NUM> through a wireless communication link.

The master mobile electronic device (also referred to as "master device" for brevity) communicates with the other mobile electronic devices <NUM> through a wireless communication link, which may use a low latency protocol such as a device-to-device communication protocol (e.g., LTE side-link protocol). The low latency protocol may, for example, be configured to provide less than <NUM> delay between the master mobile electronic device and the other mobile electronic devices <NUM>.

In some embodiments, the operations that are described as being performed by the master mobile electronic device may be performed in a distributed manner by more than one of the mobile electronic devices within an audio playout group, by the audio server <NUM>, and/or by a combination of one or more mobile electronic devices and the audio server <NUM>.

With further reference to <FIG>, the mobile electronic device <NUM> that is operating as a master may perform the operation for coordinating <NUM> timing of playout of audio media content by the group of mobile electronic devices <NUM> by controlling timing when individual ones of the mobile electronic devices <NUM> in the group initiate the playout from a common location within the audio media content to reduce time offsets between when sound emitted by the individual ones of the mobile electronic devices <NUM> from the playout arrives at the preferred listening location <NUM> where the sound transient was generated.

The operation by the master mobile electronic device for coordinating <NUM> timing of playout of audio media content by the group of mobile electronic devices <NUM> can include determining an audio playout start time relative to the common time sync based on comparison of the timing of occurrence of the sound transient sensed by the master mobile electronic device to the timing of occurrences of the sound transients sensed by other ones of the mobile electronic devices <NUM>, and initiating playout by the master mobile electronic device from the common location within the audio media content through the speaker <NUM> when the audio playout start time satisfies a defined rule relative to the common time sync. For each of the other mobile electronic devices <NUM>, the master mobile electronic device determines another audio playout start time relative to the common time sync based on comparison of the timing of occurrence of the sound transient sensed by the other mobile electronic devices <NUM> to the timing of occurrences of the sound transients sensed by other ones of the mobile electronic devices <NUM>, and transmits a playout timing message to the other mobile electronic devices <NUM> containing an indication of the other audio playout start time relative to the common time sync indicating when the other mobile electronic device <NUM> is to initiate playout from the common location within the audio media content. As an alternative, the master device may determine a relative time shift between audio played out by individual ones of the mobile electronic devices <NUM> based on comparison of the timing of occurrence of the sound transient sensed by the other mobile electronic devices <NUM> to the timing of occurrences of the sound transients sensed by other ones of the mobile electronic devices <NUM>, and transmit a playout timing message to the other mobile electronic devices <NUM> containing an indication of the relative time shift.

In a further embodiment, the operation by the master mobile electronic device for coordinating <NUM> timing of playout of audio media content by the group of mobile electronic devices <NUM> includes determining time differences between sound propagation times from the preferred listening location <NUM> where the sound transient was generated to the mobile electronic devices <NUM> in the group based on differences between the timing of occurrences sensed by the mobile electronic devices <NUM> in the group, and then determining the audio playout start time, or a relative time shift, for individual ones of the mobile electronic devices <NUM> in the group based on the time differences.

Which one of the mobile electronic devices <NUM> in the group is selected to operate as the master may be determined based on comparison of the capabilities of the various mobile electronic devices <NUM> in the group. For example, any of the mobile electronic devices <NUM> that has less than a threshold level of available memory capacity for the audio application, less than a threshold level of processor speed, less than a threshold level of quality of service of communication link to the other mobile electronic devices <NUM>, and/or which is not programmatically configured to operate as a master can be excluded from being selected as a master. The master device may be selected based on it being the first one of the mobile electronic devices <NUM> to initiate execution of the audio application. The master device may alternatively be selected based on it being the only one of the mobile electronic devices <NUM> that has access to the audio media content on an audio server, e.g., by virtue of a subscription to a streaming service like Spotify. Selection of the master device may be made by one or more of the mobile electronic devices <NUM> in the group, by the audio server <NUM>, and/or by a user operating one of the mobile electronic devices <NUM> to configure it as the master.

<FIG> is a flowchart of operations that may be performed by one of the mobile electronic devices <NUM> and/or by the audio server <NUM> to select the master device. Referring to <FIG>, prior to the operation to determine <NUM> (<FIG>) the timing of occurrence of the sound transient that is sensed by the microphone relative to the common time sync, the operations include receiving <NUM> capability reports from the other mobile electronic devices <NUM>, where each of the capability reports contains capability information indicating at least one of processor speed, memory capacity, and quality of service of a communication link to an audio server configured to serve the audio media content for playout by the group of mobile electronic devices. Based on the capability information of the mobile electronic devices <NUM>, the operations select <NUM> one of the mobile electronic devices from among the mobile electronic devices and configuring the selected mobile electronic device to operate as a master for controlling the timing of playout of the audio media content by the mobile electronic devices.

The master may control processing of the audio playout by the other mobile electronic devices <NUM>. The control of processing of the audio playout may include providing parameters that are used for audio signal processing, such as audio filter parameters. The master may designate individual roles of the other mobile electronic devices <NUM> during the audio playout, such as by designating one or more of the mobile electronic devices <NUM> to emphasize output of a base frequency range of the audio, designate one or more other of the mobile electronic devices <NUM> to emphasize output of a mid-frequency range of the audio, in designate still one or more other of the mobile electronic devices <NUM> to emphasize a highfrequency range of the audio. Alternatively or additionally the master may control which of a plurality of audio channels of the media content are played by which of the mobile electronic devices <NUM>, such as to provide stereo audio playout and/or more complex surround-sound multichannel playout. When the media content provides more audio channels than there are mobile electronic devices, the master may combine two of more of the audio channels into a combined audio channel that is then provided to a selected one of the mobile electronic devices for playing or may provide an instruction to the selected mobile electronic device that commands it to combine the two of more of the audio channels into a combined audio channel for playing.

The master may select a soundfield profile from among a defined set of soundfield profiles based on how many mobile electronic devices <NUM> are within the group. For example, the master may control the mobile electronic devices <NUM> in the group to provide stereo left audio channel and right audio channel playout when only two mobile electronic devices <NUM> have joined the group. When a third mobile electronic devices <NUM> subsequently joins the group, the master may modify the audio playout to provide a soundfield profile that uses the capabilities of all three mobile electronic devices <NUM>, such as providing left audio channel playout through the first mobile electronic devices <NUM>, mid-audio channel (or mixture of right and left audio channels) playout through the second mobile electronic devices <NUM>, and right audio channel playout through the third mobile electronic devices <NUM>. When four mobile electronic devices <NUM> are in the group, the master may cause the first mobile electronic devices <NUM> to play the left audio channel, the second mobile electronic devices <NUM> to play the right audio channel, and the third and fourth mobile electronic devices <NUM> to play the mid-audio channel (or mixture of right and left audio channels). This logical operation can be extended to any plural number N of mobile electronic devices <NUM> that are initially present in the group or which may join the group after audio playout amongst the group has started. The master may decide which of the mobile electronic devices <NUM> in the group is to have the role of playing right, left, center, etc. of the audio channels based on their respective temporal vicinity to the preferred listening location where the sound transient was generated.

<FIG> is a flowchart of corresponding operations that can be performed by one of the mobile electronic devices <NUM> operating as the master and/or by the audio server <NUM> operating as the master. Referring to <FIG>, the operations include selecting <NUM> a soundfield profile from among a set of soundfield profiles based on a number of the mobile electronic devices <NUM> in the group, and controlling <NUM> which of a plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the group based on the selected soundfield profile. Further operations may include further controlling which of the plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the group based on speaker capabilities identified for the mobile electronic devices <NUM> in the group. For example, when one of the mobile electronic devices <NUM> has a speaker capable of high power output low frequency response, the master may select a soundfield profile that more optimally uses the low frequency response of that mobile electronic device <NUM>.

The master may mix and/or filter (e.g., adjust the frequency spectral waveform) of the audio channels to combine audio channels or to generate additional audio channels for playing through the mobile electronic devices <NUM> depending upon the number of mobile electronic devices <NUM> in the group and/or depending upon the number of different roles being assigned to the group. The operations for mixing and/or filtering the audio may be based on those disclosed in "<NPL>.

The operation for comparing <NUM> the timing of occurrence of the sound transient sensed by the microphone of one of the mobile electronic device <NUM> and the timing of occurrences indicated by the timing reports received from the other mobile electronic devices <NUM>, may include cross-correlating between recordings of the sound transient sensed by the microphones to identify timing offsets between the timing of occurrences of receipt of the sound transient by the mobile electronic devices <NUM> (e.g., when sensed by the microphones). The master (either the master mobile electronic device or the audio server <NUM>) may determine a joint-playing soundfield based on the results of the cross-correlation so that a more optimal listening soundfield is created at the preferred listening location where the sound transient was generated. The joint-playing soundfield may be determined based on a determination of temporal vicinity of respective ones of the mobile electronic devices <NUM> to the preferred listening location where the sound transient was generated. In addition to controlling timing of playout of audio media content by each of the mobile electronic devices <NUM> in the group, the master may also assign roles to each of mobile electronic devices <NUM> in the group based on the number of mobile electronic devices <NUM> and their respective determined temporal vicinity.

The master may communicate instruction(s) to the mobile electronic devices <NUM> to start a listening mode that determines a timing of occurrence for when a sound transient is sensed by the microphone relative to the common time sync. A corresponding operation by the master can include transmitting a listening mode signal to the other mobile electronic devices <NUM> to initiate listening by the other mobile electronic devices <NUM> for occurrence of the sound transient and resulting transmissions of the timing reports. Once the mobile electronic devices <NUM> have all entered the listening mode, a user may generate the sound transient, e.g., hand clap, knock on a table, etc., at the preferred listening location or an application on one of the mobile electronic devices at the preferred listening location can output the sound transient toward the mobile electronic devices <NUM> for their separate sensing, measurement, and reporting to the master for processing.

Three approaches are now described which the master device may alternatively perform to control the coordinated audio stream playout by a group of the mobile electronic devices <NUM>.

In a first approach, each of the mobile electronic devices <NUM> in the playout group has access to the audio media content, such as by having downloaded the content from the audio server <NUM> and/or by having established a communication link with the audio server <NUM> to receive streamed content. One of the mobile electronic devices <NUM> operating as a master sends audio filter parameters to the mobile electronic devices <NUM> for their use to control audio processing while playing the audio media content through their speakers. <FIG> is a flowchart of operations that may be performed by the master in accordance with this approach. Referring to <FIG>, the master measures <NUM> magnitude over time of the sound transient sensed by the microphone. For each of the received timing reports from the other mobile electronic devices <NUM>, the master device extracts <NUM> from the timing report measurements of magnitude over time of the sound transient sensed by the other mobile electronic device. The master determines <NUM> audio filter parameters for each of the mobile electronic devices <NUM> in the group based on their respective measurements of the magnitude over time of the sound transient. The master filters <NUM> the audio media content during playout through the speaker using the audio filter parameters determined for the mobile electronic device, and transmits <NUM> audio filter messages to the other mobile electronic devices <NUM> containing indications of the audio filter parameters determined for respective ones of the other mobile electronic devices <NUM> to control filtering of the audio media content during playout.

In a second approach, when one of the mobile electronic devices <NUM> is operating as a master and is the only one of the mobile electronic devices <NUM> that has access to the audio media content, the master can pre-process the audio media content that it then communicates to the other mobile electronic devices <NUM>. <FIG> is a flowchart of operations that may be performed by the master in accordance with this approach. Referring to <FIG>, the master receives <NUM> from the other mobile electronic devices <NUM> measurements of magnitude over time of the sound transient sensed by the other mobile electronic devices <NUM>. The master determines <NUM> audio filter parameters based on comparison of the measurements of the magnitude over time of the sound transient to the measurements of the magnitude over time of the sound transient obtained from the other mobile electronic devices in the group. The master filters <NUM> the audio media content using the audio filter parameters to generate filtered audio media content. The master transmits <NUM> the filtered audio media content to the other mobile electronic devices for playout.

In a third approach, each of the mobile electronic devices <NUM> in the group can report their audio processing parameters to the audio server <NUM> which then are used to generate separate audio streams and/or audio files that are adapted specifically for playout by particular ones of the mobile electronic devices <NUM> based on the reported audio processing parameters. The audio server <NUM> may be configured to perform the operations described above for steps <NUM>-<NUM> in <FIG>. In one embodiment, the mobile electronic devices <NUM> filter the audio media content that they played through their speaker based on audio filter parameters that are generated and provided by the audio server <NUM> to the mobile electronic devices <NUM>. In this embodiment, a mobile electronic device <NUM> measures magnitude over time of the sound transient sensed by the microphone, and communicates to the audio server <NUM> indications of the measurements of magnitude over time of the of the sound transient. The mobile electronic device <NUM> then receives an audio filter message from the audio server <NUM> containing audio filter parameters, and filters the audio media content during playout through the speaker using the audio filter parameters. As will be explained in further detail below, the master (i.e., one of the mobile electronic devices <NUM> and/or the audio server) can generate audio filter parameters to provide a more optimized soundfield at the preferred listening location that is adapted based on the reverse sounding computations, based on loss of one or more of the mobile electronic devices <NUM> from the playout group, and/or based on addition of one or more new mobile electronic devices to the playout group.

In some other embodiments, the audio server <NUM> operates as the master to control timing of playout of the audio media content by the mobile electronic devices <NUM> in the playout group.

<FIG> is a flowchart of operations that may be performed by the audio server <NUM> operating as the master to control the coordinated playout of audio media content through a group of mobile electronic devices <NUM>. <FIG> is a block diagram of elements of an audio server <NUM>. Referring to <FIG> and <FIG>, the audio server <NUM> may include a network interface circuit <NUM>, a processor <NUM>, and a memory <NUM> storing program code <NUM> that is executed by the processor to perform operations. The operations can include receiving <NUM> timing reports from the mobile electronic devices <NUM>. Each of the timing reports can indicate a timing of occurrence of a sound transient sensed by a microphone of a respect one of the mobile electronic devices <NUM> relative to a common time sync shared among the mobile electronic devices <NUM>. The sound transient that is sensed by the mobile electronic devices is generated at a preferred listening location <NUM> (<FIG>). The operations further include controlling <NUM> timing of play out of audio media content by the group of mobile electronic devices <NUM> responsive to comparison of the timing of occurrences indicated by the timing reports.

With the audio server <NUM> operating as the master, the operation for controlling <NUM> timing of play out of audio media content by the group of mobile electronic devices <NUM> responsive to comparison of the timing of occurrences indicated by the timing reports, can include controlling timing when individual ones of the mobile electronic devices <NUM> in the group initiate the playout from a common location within the audio media content to reduce time offsets between when sound emitted by the individual ones of the mobile electronic devices <NUM> from the playout arrive at the preferred listening location <NUM> where the sound transient was generated.

Alternatively or additionally, with the audio server <NUM> operating as the master, the operation for controlling <NUM> timing of playout of audio media content by the group of mobile electronic devices <NUM> responsive to comparison of the timing of occurrences indicated by the timing reports, can include the following operations. For each of the mobile electronic devices <NUM> in the group, the operations determine an audio playout start time relative to the common time sync based on comparison of the timing of occurrence of the sound transient sensed by the mobile electronic device <NUM> to the timing of occurrences of the sound transients sensed by other ones of the mobile electronic devices <NUM> in the group, and transmit a playout timing message to the mobile electronic device <NUM> containing an indication of the other audio playout start time relative to the common time sync. The operations for determining the audio playout start times for the mobile electronic devices <NUM> in the group may include determining time differences between the sound propagation times from the preferred listening location <NUM> where the sound transient was generated to the mobile electronic devices <NUM> in the group, based on differences between the timing of occurrences reported in the timing reports. The audio playout start times are then determined based on the time differences.

<FIG> is a flowchart of further operations that may be performed by the audio server <NUM> operating as the master to control the coordinated playout of audio media content through a group of mobile electronic devices <NUM>. Referring to <FIG>, the audio server <NUM> selects <NUM> a soundfield profile from among a set of soundfield profiles based on a number of the mobile electronic devices <NUM> in the group. The audio server <NUM> controls <NUM> which of a plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the group based on the soundfield profile that is selected. Operations by the audio server <NUM> may further include controlling which of the plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices in the group based on speaker capabilities identified for the mobile electronic devices in the group.

The audio server <NUM> may control when the mobile electronic devices <NUM> and operate to listen for the sound transient to generate the associated report to the audio server <NUM>. Audio server <NUM> may transmit a listening mode signal to the mobile electronic devices <NUM> to initiate listening by the mobile electronic devices <NUM> for occurrence of the sound transient and resulting transmissions of the timing reports to the audio server <NUM>.

<FIG> is a flowchart of further operations that may be performed by the audio server <NUM> operating as the master to control the coordinated playout of audio media content through a group of mobile electronic devices <NUM>. Referring to <FIG>, the operation for receiving <NUM> timing reports from the other mobile electronic devices <NUM>, can include performing for each of the received timing reports a cross-correlation <NUM> between recordings of the sound transient received in the timing reports to identify timing offsets between the timing of occurrences of the sound transient.

<FIG> is a flowchart of further operations that may be performed by the audio server <NUM> when operating as the master to control the coordinated playout of audio media content through a group of mobile electronic devices <NUM>. Referring to <FIG>, further operations can include receiving <NUM> measurements of magnitude over time of the sound transient sensed by the mobile electronic devices <NUM> in the group. The operations can include determining <NUM> audio filter parameters for each of the mobile electronic devices <NUM> in the group based on their respective measurements of the magnitude over time of the sound transient.

In one embodiment, the audio server <NUM> transmits <NUM> audio filter messages to the mobile electronic devices <NUM> in the group containing indications of the audio filter parameters determined for respective ones of the mobile electronic devices to control their filtering of the audio media content during playout.

In an alternative embodiment, the audio server <NUM> filters <NUM> the audio media content using the audio filter parameters to generate filtered audio media content, and communicates the filtered audio media content to the mobile electronic device <NUM> in the group for playout.

<FIG> is a flowchart that summarizes operations that can be performed by the users, one of the mobile electronic devices <NUM> designated as the master device <NUM> and the other mobile electronic devices designated as the client devices <NUM> to provide more optimized playout of audio media content in accordance with some embodiments.

Referring to <FIG>, users place <NUM> the mobile electronic devices (devices) at intended play positions in a room. The users start <NUM> operation of a joint playout application in the devices. The devices operate <NUM> to communicatively connect, share capabilities, identify one of the devices with the best capability to operate as the master device, and agree on a common time sync. The master device selects <NUM> an initial stereo or multi-channel audio profile based on the number of connected devices in the playout group. The master device requests <NUM> the user to locate to the preferred listening location. The master device orders <NUM> the group of devices into a listening mode to wait for receipt of a sound transient created by a knock/handclap. The master device displays a countdown to the user when the user is to generate the sound transient. The client devices <NUM>, also referred to as slave devices or other mobile electronic devices, perform operations that store <NUM> an audio channel impulse profile of the sensed sound transient and share <NUM> the audio channel impulse profiles with the master device <NUM>. The master device <NUM> performs operations to store <NUM> an audio channel impulse profile of the sensed sound transient, find <NUM> one of the devices having the shortest signal path to the preferred listening location, calculate <NUM> timing differences between receipt of the sound transient by the devices to provide the same impulse profile as for the closest device, calculate audio mixing for each device (either by sending audio filter parameters or pre-mixed audio to the client devices <NUM>, depending on the devices and location of audio source). The master device <NUM> may determine <NUM> the audio filter parameters based on the timing differences of (between receipt of the sound transient by) the devices, such as relative to the device that has the least audio delay to receipt of the sound transient from the preferred listening location. Master device <NUM> transmits <NUM> the audio filter parameters to the client devices <NUM>. The master device <NUM> performs <NUM> timing difference compensation and/or other audio processing for audio playout based on the audio filter parameters, coordinates <NUM> timing of playout of audio media content by the client devices <NUM> in the master device <NUM> to compensate for the timing differences, and plays-out <NUM> the mixed and filtered audio from its speaker. The client devices <NUM> perform <NUM> timing compensation and/or other audio processing for audio playout based on the audio filter parameters, coordinate <NUM> timing of play out of their audio media content based on signaling from the master device <NUM> to compensate for their respective timing differences, and playout <NUM> the mixed and filtered audio from their respective speakers. Thus, for example, devices that are closer to the preferred listening location may be controlled to delay their playout of a time instant in the media content compared to devices that are further from the preferred listening location, so that the audio playout from all of the devices is coordinated to arrive at nearly a same time to the preferred listening location.

Playout of audio media content by the mobile electronic devices <NUM> in a group may be dynamically adapted by the master to compensate for loss of one or more of the mobile electronic devices <NUM> from the playout group and/or to compensate for the addition of one or more new mobile electronic devices <NUM> to the playout group. The master may perform the compensation using a pre-calculated table of audio filter parameters. For example, the master may refer to a pre-calculated table that identifies various alternative filter parameters that can be used by the mobile electronic devices during playout and which are selected among based on how many mobile electronic devices <NUM> are participating in the playout group.

Responsive to determining that one of the mobile electronic devices <NUM> is no longer available to participate in the playout group, the master selects based on the remaining number of mobile electronic devices <NUM> in the playout group a new entry in a table of audio filter parameters which is used by the master to filtered audio media content for playout by the remaining mobile electronic devices <NUM> or is communicated to the remaining mobile electronic devices <NUM> for their use when processing the audio media content for playout through their speakers. The master may determine that a mobile electronic device has left the playout group based on, for example, presence information periodically reported by each of the mobile electronic devices <NUM> and/or identifying an absence of signaling from one of the mobile electronic devices <NUM> for more than a threshold time. The master may thereby dynamically respond to loss of a mobile electronic device <NUM> from the playout group by responsively selecting another entry from the table of audio filter parameters that will cause the remaining mobile electronic devices <NUM> in the playout group to adapt their playout to provide a more optimized soundfield.

In the scenario where only the master stores or retrieves (e.g., by streaming) the unprocessed audio content, the master may apply the newly selected audio filter parameters to filter the audio media content to result in adaptation of the soundfield, and stream the filtered audio media content to the respective mobile electronic devices <NUM> or communicate a filtered media content file to the respective mobile electronic devices <NUM> for playout. Alternatively, the master may communicate the newly selected audio filter parameters to the mobile electronic devices <NUM> for their respective use in adapting the soundfield of the audio media content, received in a stream or file from the master, which they then playout through their speakers.

Conversely, the master may respond to a determination that a new mobile electronic device <NUM> is available to join the playout group, by selecting a new entry in a table of audio filter parameters which is used by the master to filter the audio media content for playout by the new and previously existing mobile electronic devices <NUM> in the playout group. Alternatively, the selected audio filter parameters may be communicated to the new and existing mobile electronic devices <NUM> for their use when processing the audio media content for playout through their speakers. The master may repeat the operations for determining timing differences between receipt of the sound transient by the mobile electronic devices <NUM> (e.g., reverse sounding process) to determine the spatial positioning of the new mobile electronic device <NUM> relative to the preferred listening location <NUM>. For example, the master may prompt the listening user to carry out a new knock/hand clap at the preferred listening location <NUM> for the new mobile electronic device <NUM> to sense and report to the master for use in selecting new audio filter parameters for use by the new mobile electronic device <NUM> and/or by the existing mobile electronic devices <NUM>. As explained above, the roles of some or all of the mobile electronic devices <NUM> in the playout group can be modified responsive to addition of one or more new mobile electronic devices <NUM> to the playout group or loss of one or more of the mobile electronic devices <NUM> from the playout group.

In one variant of the above embodiment, the master may assign a playout role, for example playing lower base tones, to a new mobile electronic device <NUM> that is less affected by differences between audio travel time from the new mobile electronic device <NUM> to the preferred listening location <NUM> relative to the other mobile electronic devices <NUM> and the preferred listening location <NUM>, until the reverse sounding process (i.e., process for compensating for audio travel time difference) is repeated. Upon completion of the repeated reverse sounding process, the master may assign another playout role to the new mobile electronic device <NUM>.

<FIG> is a flowchart of operations that may be performed by one of the mobile electronic devices <NUM> that is operating as a master for controlling playout of audio media content by the playout group.

Referring to <FIG>, in one embodiment, the master selects <NUM> a soundfield profile from among a set of soundfield profiles based on a number of the mobile electronic devices <NUM> in the playout group. The master controls <NUM> which of a plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the playout group based on the selected soundfield profile. Responsive to determining <NUM> that one of the mobile electronic devices <NUM> in the playout group has ceased participating in the playout of the audio media content, the master selects another soundfield profile from among the set of soundfield profiles based on a remaining number of the mobile electronic devices <NUM> in the playout group, and further controls which of the plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> remaining in the playout group based on the selected soundfield profile.

With continuing reference to <FIG>, in another embodiment, the master selects <NUM> a soundfield profile from among a set of soundfield profiles based on a number of the mobile electronic devices <NUM> in the playout group. The master controls <NUM> which of a plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the playout group based on the selected soundfield profile. Responsive to determining <NUM> that a new mobile electronic device seeks to join the playout group of mobile electronic devices <NUM> for playout of the audio media content, the master selects another soundfield profile from among the set of soundfield profiles based on the increased number of the mobile electronic devices <NUM> in the expanded group by addition of the new mobile electronic device, and further controls which of the plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the expanded group based on the selected soundfield profile.

The operation to select <NUM> another soundfield profile from among the set of soundfield profiles based on the increased number of the mobile electronic devices <NUM> in the expanded group by addition of the new mobile electronic device, may include selecting a soundfield profile for an audio channel of the audio media content to be played by the new mobile electronic device that will decrease distortion perceived by a listener when the sound generated by the new mobile electronic devices arrives and combines at the preferred listening location <NUM>, where the sound transient was generated, to combine with the sounds generated by other ones of the mobile electronic devices <NUM> in the expanded group of mobile electronic devices. The master controls the new mobile electronic device to play out the audio channel of the audio media content selected for the new mobile electronic device.

In some other embodiments, the audio server <NUM> operates as the master to control playout of the audio media content by the mobile electronic devices <NUM> in the playout group.

In one embodiment, the audio server <NUM> performs operations that include selecting a soundfield profile from among a set of soundfield profiles based on a number of the mobile electronic devices <NUM> in the playout group. The operations control which of a plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the playout group based on the selected soundfield profile. Responsive to determining that one of the mobile electronic devices <NUM> in the playout group has ceased participating in the playout of the audio media content, the operations select another soundfield profile from among the set of soundfield profiles based on a remaining number of the mobile electronic devices <NUM> in the playout group, and further control which of the plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> remaining in the group based on the selected soundfield profile.

In another embodiment, the operations by the audio server <NUM> include selecting a soundfield profile from among a set of soundfield profiles based on a number of the mobile electronic devices <NUM> in the playout group. The operations control which of a plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the playout group based on the selected soundfield profile. Responsive to determining that a new mobile electronic device <NUM> seeks to join the playout group of mobile electronic devices <NUM> for playout of the audio media content, the operations select another soundfield profile from among the set of soundfield profiles based on the increased number of the mobile electronic devices <NUM> in the expanded group by addition of the new mobile electronic device <NUM>, and further control which of the plurality of separate audio channels of the audio media content are played back by which of the mobile electronic devices <NUM> in the expanded group based on the selected soundfield profile.

The operation by the audio server <NUM> to select another soundfield profile from among the set of soundfield profiles based on the increased number of the mobile electronic devices <NUM> in the expanded group by addition of the new mobile electronic device <NUM>, may include selecting a soundfield profile for an audio channel of the audio media content to be played by the new mobile electronic device <NUM> that will decrease distortion when the sound generated by the new mobile electronic devices <NUM> arrives at the preferred listening location <NUM>, where the sound transient was generated, to combine with the sounds generated by other ones of the mobile electronic devices <NUM> in the expanded group of mobile electronic devices <NUM>. The audio server <NUM> controls the new mobile electronic device <NUM> to play out the audio channel of the audio media content selected for the new mobile electronic device <NUM>.

The master may measure reverberation contained in the sound transients reported by the mobile electronic devices <NUM> to, for example, characterize reflections by physical objects, e.g., walls, present in the room. The master may measure other audio characteristics of the room based on data reported by the mobile electronic devices <NUM> for a sequence of sound transients event generated at the preferred listening location. The master may use this information when generating the audio filter parameters and/or when selecting the soundfield profile to be used by the various mobile electronic devices <NUM> in the playout group in order to achieve a more optimal play out at the preferred listening location.

<FIG> is a flowchart of operations that may be performed by one of the mobile electronic devices <NUM> that is operating as a master for controlling playout of audio media content by the playout group. Referring to <FIG>, the master measures <NUM> reverberation of the sound transient that is sensed by the microphone. For each of the other mobile electronic devices <NUM> in the playout group, the master determines <NUM> from the timing report of the other mobile electronic device <NUM> reverberation of the sound transient that is sensed by the microphone of the other mobile electronic device <NUM>. The master for the coordinates <NUM> timing of play out of audio media content by the group of mobile electronic devices <NUM> responsive to comparison of the measurements of reverberations by the mobile electronic devices <NUM> in the playout group.

The master may determine a desired echo and/or reverberation that is to be generated at the preferred listening location during playout of the audio media content by the mobile electronic devices <NUM>, and determine timing differences between receipt of the sound transient by the group of the mobile electronic devices <NUM> and playout delay settings that are used when coordinating timing of playout of audio media content by the group of mobile electronic devices <NUM>.

In some embodiments, the audio server <NUM> operates as the master to control playout of the audio media content by the mobile electronic devices <NUM> in the playout group. In one embodiment, the audio server <NUM> operates to, for each of the mobile electronic devices <NUM>, determine from the timing report of the mobile electronic device <NUM> reverberation of the sound transient that is sensed by the microphone of the mobile electronic device <NUM>. The audio server <NUM> operates to further control timing of playout of audio media content by the playout group of mobile electronic devices <NUM> responsive to comparison of the measurements of reverberations by the mobile electronic devices <NUM> in the playout group.

When the master detects one or more of the play out-devices are being moved from their respective initial positions, the master responds to determining that one or more dislocations has become larger than a predefined threshold by pausing the audio playout of the mobile electronic devices <NUM> and initiating another reverse sounding process. Alternatively, when the remaining duration of an ongoing audio playout (e.g., song) is less than a defined duration, the master may wait for the audio playout to complete and then initiate another reverse sounding process before allowing another audio playout (e.g., next song in playlist) to begin playout by the mobile electronic devices <NUM> in the playout group.

<FIG> is a flowchart of operations that may be performed by one of the mobile electronic devices <NUM> that is operating as a master for controlling playout of audio media content by the playout group. Referring to <FIG>, the master receives <NUM> signaling indicating that one of the other mobile electronic devices <NUM> may have moved at least a threshold distance. Responsive to a recalibration rule becoming satisfied based on the signaling, the master repeats <NUM> at least the step of receiving <NUM> (<FIG>) a timing report from at least the one of the other mobile electronic devices <NUM> and the step of coordinating <NUM> (<FIG>) timing of playout of audio media content.

When the audio server <NUM> is operating as the master to control playout of the audio media content by the mobile electronic devices <NUM>, the audio server <NUM> receives signaling indicating that one of the other mobile electronic devices <NUM> may have moved at least a threshold distance. Responsive to a recalibration rule becoming satisfied based on the signaling, the audio server <NUM> repeats at least the step of receiving <NUM> (of <FIG>) a timing report from at least the one of the other mobile electronic devices and the step of coordinating <NUM> (of <FIG>) timing of play out of audio media content.

The mobile electronic devices <NUM> which belong to a playout group may each execute an application for streaming music (or other audio content), such as Spotify, from an audio server <NUM> that is configured to support synchronized playout of the music using the mobile electronic devices <NUM> as distributed speakers. The mobile electronic devices <NUM> in the playout group may report their captured sound transients to the audio server <NUM> associated with the application. The audio server <NUM> manages reverse sounding processes, time synchronization, adjusts the filter parameters and/or the sound field of the mobile electronic devices <NUM> of the playout group, and controls timing of play out of the music through the mobile electronic devices <NUM>. The audio server <NUM> generates a dedicated music stream for each of the mobile electronic devices <NUM> in the playout group, where each stream may be generated according to various operations described above for the first aspects section. This may be advantageous in that the resource (battery) demanding processing for operations of reverse sounding, filter parameters and/or sound field selection, time synchronization, and controlling timing of playout are primarily performed by the audio server <NUM> instead of by the battery-powered mobile electronic devices <NUM>.

Various operations that can also be performed by the audio server <NUM> operating as the master have been described above including with regard to <FIG>.

<FIG> is a flowchart that summarizes operations that can be performed by the users, the mobile electronic devices <NUM> (referred to as "client devices: in <FIG>), and the audio server <NUM> (referred to as "server" in <FIG>) to provide more optimized playout of audio media content through the mobile electronic devices <NUM> in accordance with some embodiments.

Referring to <FIG>, users place <NUM> the mobile electronic devices (devices) at intended play positions in a room. The users start <NUM> operation of a joint playout application in the devices. The devices operate <NUM> to communicatively connect, share capabilities, identify one of the devices with the best capability to operate as the master device, and agree on a common time sync. In some embodiments, the operations include: the devices communicating <NUM> a group ID/shared secret to the audio server <NUM>; the audio server <NUM> connects <NUM> users having a same group ID to form a playout group; the audio server <NUM> assigns <NUM> a master device for latency and other sound transient related calculations; and the audio server selects an initial soundfield profile based on the number of mobile electronic devices in the playout group. The master device requests <NUM> the user to locate to the preferred listening location, which can also be referred to as the preferred listening location. The master device orders <NUM> the group of devices into a listening mode to wait for receipt of a sound transient created by a knock/handclap. The master device displays a countdown to the user when the user is to generate the sound transient.

The mobile electronic devices <NUM>, also referred to as client devices, perform operations that store <NUM> an audio channel impulse profile of the sensed sound transient and share <NUM> the audio channel impulse profiles with the audio server <NUM>. The audio server <NUM> performs <NUM> estimation of timing differences between receipt by the mobile electronic devices <NUM> of the sound transient generated from the preferred listening location, and generates audio filter parameters the compensate for differences in the timing of receipt of the sound transients by the client devices. The audio server <NUM> can use <NUM> the audio filter parameters to filter the audio content that is then transferred to each of the client devices, and can provide time shift and amplitude-filter correction that compensates for the audio characteristics of the room and the positioning of the client devices relative to the preferred listening location. The client devices receive the audio content from the audio server <NUM> and play the audio content through their respective speakers.

Some or all operations described above as being performed by the mobile electronic devices <NUM> and/or the audio server <NUM> may alternatively be performed by another node that is part of a cloud computing resource. For example, those operations can be performed as a network function that is close to the edge, such as in a cloud server or a cloud resource of a telecommunications network operator, e.g., in a CloudRAN or a core network, and/or may be performed by a cloud server or a cloud resource of a media provider, e.g., iTunes service provider or Spotify service provider.

<FIG> is a block diagram of components of a mobile electronic device <NUM> that are configured in accordance with some other embodiments of the present disclosure. The mobile electronic device <NUM> can include a wireless network interface circuit <NUM>, a location determination and/or motion determination circuit <NUM>, a microphone <NUM>, an audio output interface <NUM> (e.g., speaker, headphone jack, wireless transceiver for connecting to wireless headphones), a display device <NUM>, a user input interface <NUM> (e.g., keyboard or touch sensitive display), at least one processor circuit <NUM> (processor), and at least one memory circuit <NUM> (memory). The processor <NUM> is connected to communicate with the other components. The memory <NUM> stores an audio playout synchronization application <NUM> that is executed by the processor <NUM> to perform operations disclosed herein. The processor <NUM> may include one or more data processing circuits, such as a general purpose and/or special purpose processor (e.g., microprocessor and/or digital signal processor), which may be collocated or distributed across one or more data networks. The processor <NUM> is configured to execute computer program instructions in the memory <NUM>, described below as a computer readable medium, to perform some or all of the operations and methods for one or more of the embodiments disclosed herein for a mobile electronic device.

<FIG> is a block diagram of components of an audio server <NUM> which operate according to at least some embodiments of the present disclosure. The audio server <NUM> can include a network interface circuit <NUM>, at least one processor circuit <NUM> (processor), and at least one memory circuit <NUM> (memory). The network interface circuit <NUM> is configured to communicate with mobile electronic devices via networks which can include wireless and wired networks. The audio server <NUM> may further include the audio playout synchronization application <NUM> to synchronize playout of audio media content from an audio media content repository <NUM> by the mobile electronic devices. The audio media content repository <NUM> may be part of the audio server <NUM> or may be communicatively networked to the audio server <NUM> through the network interface circuit <NUM>. The audio server <NUM> may further include a display device <NUM> and a user input interface <NUM>. The memory <NUM> stores program code that is executed by the processor <NUM> to perform operations. The processor <NUM> may include one or more data processing circuits, such as a general purpose and/or special purpose processor (e.g., microprocessor and/or digital signal processor), which may be collocated or distributed across one or more data networks. The processor <NUM> is configured to execute computer program instructions among program code in the memory <NUM>, described below as a computer readable medium, to perform some or all of the operations and methods for one or more of the embodiments disclosed herein for a map route server.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which present inventive concepts belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense expressly so defined herein.

Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of inventive concepts defined by the appended claims.

Claim 1:
A mobile electronic device (<NUM>) operating with other mobile electronic devices forming a group for coordinated playout of audio media content, the mobile electronic device (<NUM>) comprising:
a wireless network interface circuit (<NUM>) configured for communication with the other mobile electronic devices through a wireless communication link;
a microphone (<NUM>);
a speaker (<NUM>);
a processor (<NUM>) operationally connected to the microphone, the speaker, and the wireless network interface circuit; and
a memory (<NUM>) storing program code (<NUM>) that is executed by the processor to perform operations comprising:
determining a common time sync shared with the other mobile electronic devices;
determining a timing of occurrence of a sound transient that is sensed by the microphone relative to the common time sync;
receiving timing reports from the other mobile electronic devices, wherein each of the timing reports indicates a timing of occurrence of the sound transient sensed by a microphone of a respective one of the other mobile electronic devices relative to the common time sync, wherein the sound transient sensed by the mobile electronic devices is generated at a preferred listening location; and
coordinating timing of play out of audio media content by the group of mobile electronic devices responsive to comparison of the timing of occurrence of the sound transient sensed by the microphone of the mobile electronic device and the timing of occurrences indicated by the timing reports.