Acoustic Shock Prevention Apparatus

0001The present invention relates to apparatus for prevention of acoustic shock in processing of audio signals. The invention further relates to, but is not limited to, apparatus for prevention of acoustic shock in processing audio and speech signals in audio playback devices.

0002Audio processing and in particular audio processing in mobile devices have been a growing area in recent years.

0003These mobile devices/portable devices are typically capable of operating or performing several different tasks either subsequently and/or in parallel. For example a mobile device may be capable of performing actions such as, for example, telecommunication playback, audio playback, audio-video playback, audio alert, navigation alert command, radio broadcast playback, and so on. In some circumstances when a use or state of operation of a device is succeeded by a different state where at least the latter state uses the integrated loudspeaker there can be a period of acoustic shock. For example the user could operate the mobile device in a telephone mode which is succeeded by the integrated loudspeaker of the device generating an alert tone, for example to alert the user that there is a further incoming phone call (or a navigational instruction). The difference in sound pressure between the two states could cause a temporary or permanent disturbance of the functioning of the ear, or of the nervous system.

0004Typically there are no or limited sound pressure limits (for example a sound pressure control set to a maximum sound pressure level to prevent physical damage to the transducer) for operating the integrated handsfree speaker or transducer. In such cases acoustic shock is a problem particularly where the integrated handsfree speaker and earpiece output ports of a mobile device are physically close to each other (for example less than 10 cm apart). This problem increases in devices which use a single speaker solution also known as two-in-one/three-in-one multifunction device integrated handsfree speaker systems. A multifunction device (MFD) is the term typically given to a combined Speaker/EarpieceNibra device. MFD can typically be used as a 2-in-1 or 3-in-1 solution. A 2-in-1 solution is where the MFD is either a Speaker/Earpiece. The 3-in-1 solution is where the MFD is a Speaker/Earpiece/Vibra.

0005In such single speaker systems the transition from one state or use case to the next when the audio mode is changed from earpiece to integrated handsfree speaker can cause particular severe acoustic shock to the user of the device as the user would have placed the device close to the ear when operation in the earpiece mode. For example a phone call using the earpiece which ends and is followed by a previously paused or subsequently implemented audio MP3 playback mode over the integrated handsfree speaker could result in a sound pressure level differential likely to cause damage to the user.

0006This, for example, is shown in <figref idref="DRAWINGS">FIG. 3</figref> whereby the apparatus <b>10</b> comprises a first integrated handsfree speaker <b>119</b> located near one end of the device <b>10</b> (near the microphone region) which produces acoustic waves non-adjacent to the ear <b>207</b>, an ear piece transducer <b>120</b> which is used in earpiece mode audio operation, and a second integrated handsfree speaker <b>117</b> near or adjacent to the location of the earpiece <b>120</b>. In this example the user <b>251</b> has just finished an earpiece associated use case or action when the device <b>10</b> activates an integrated handsfree use case whereby receives the waveform <b>201</b> for the first integrated handsfree speaker <b>117</b> and waveform <b>203</b> for the second integrated handsfree speaker <b>119</b> causes acoustic shock experienced by the user <b>251</b>.

0007Many different use case changes could cause acoustic shock for example but not exclusively: a phone call over earpiece mode which then is succeeded by a new alert tone (for example indicating a new incoming call, multimedia message service (MMS) message or short message service (SMS) message received) which is played over the integrated handsfree speaker; a phone call using the earpiece which is succeeded by video playback using audio over the integrated handsfree speaker, a phone call using the earpiece which is succeeded by music playback over the integrated handsfree speaker; a phone call over an earpiece mode is succeeded by FM radio playback over the integrated handsfree speaker; and a phone call over the earpiece mode is succeeded by car navigation commands played over the integrated handsfree speaker.

0008This invention thus proceeds from the consideration that acoustic shock prevention can be achieved by introducing control mechanisms and monitor use case transitions.

0009Embodiments of the present invention aim to address the above problem.

0010There is provided according to a first aspect of the invention a method comprising: determining a change of state in an apparatus within a first time period, wherein a first state operates with a first audio output having a first average sound pressure level and a second state operates with a second audio output having a higher average sound pressure level; and processing the second audio output signal such that the second audio output sound pressure level is acoustically continuous with respect to the first average sound pressure level immediately following the change of state.

0011Processing the second audio output signal may comprise at least one of: muting the second audio output for a muting time period; and ramping the second audio output for an audio ramp time period.

0012Ramping the second audio output for an audio ramp time period may comprise at least one of: linear ramping; and non-linear ramping;

0013Determining a change of state in an apparatus may comprise: determining an ending of the first state, wherein the first state is a member of a first group of states; and determining a start of the second state, wherein the second state is a member of a second group of states.

0014Each member of the first group of states may operate with the first audio output generated by an earpiece transducer.

0015The first group of states may comprise at least: telecommunication earpiece audio playback.

0016Each member of the second group of states may operate with the second audio output generated by an integrated handsfree transducer.

0017The second group of states may comprise: integrated handsfree speaker alert tone playback; integrated handsfree speaker music playback; integrated handsfree speaker frequency modulation (FM) radio playback; integrated handsfree speaker digital radio such as DAB (Digital Audio Broadcasting) or DRM (Digital Radio Mondiale) playback; integrated handsfree speaker amplitude modulation (AM) radio playback; integrated handsfree speaker navigation command playback; and integrated handsfree speaker video playback.

0018The method may further comprise: determining the maximum value of the higher average sound pressure level is greater than a threshold value; and wherein processing the second audio output signal further comprises limiting the maximum value of the higher average sound pressure value to the threshold value.

0019The second state may further operates with a third audio output located physically separate from the first audio output; and processing the third audio output signal such that the third audio output sound pressure level is unchanged.

0020According to a second aspect of the invention there is provided an apparatus comprising at least one processor and at least one memory, the at least one memory and the computer program code is configured to, with the at least one processor, cause the apparatus at least to perform: determining a change of state in the apparatus within a first time period, wherein a first state operates with a first audio output having a first average sound pressure level and a second state operates with a second audio output having a higher average sound pressure level; and processing the second audio output signal such that the second audio output sound pressure level is acoustically continuous with respect to the first average sound pressure level immediately following the change of state.

0021Processing the second audio output signal may cause the apparatus at least to perform at least one of: muting the second audio output for a muting time period; and ramping the second audio output for an audio ramp time period.

0022Ramping the second audio output for an audio ramp time period may cause the apparatus at least to perform at least one of: linear ramping; and non-linear ramping.

0023Determining a change of state may cause the apparatus at least to perform: determining an ending of the first state, wherein the first state is a member of a first group of states; determining a start of the second state, wherein the second state is a member of a second group of states.

0024Each member of the first group of states may operate with the first audio output generated by an earpiece transducer.

0025The first group of states may comprise at least: telecommunication earpiece audio playback.

0026Each member of the second group of states may operate with the second audio output generated by an integrated handsfree transducer.

0027The second group of states may comprise: integrated handsfree speaker alert tone playback; integrated handsfree speaker music playback; integrated handsfree speaker frequency modulation (FM) radio playback; integrated handsfree speaker digital radio such as DAB (Digital Audio Broadcasting) or DRM (Digital Radio Mondiale) playback; integrated handsfree speaker amplitude modulation (AM) radio playback; integrated handsfree speaker navigation command playback; and integrated handsfree speaker video playback.

0028The apparatus may be further caused to perform: determining the maximum value of the higher average sound pressure level is greater than a threshold value; and wherein processing the second audio output signal further comprises limiting the maximum value of the higher average sound pressure value to the threshold value.

0029The second state may further operate with a third audio output located physically separate from the first audio output; and the apparatus may be further caused to perform processing the third audio output signal such that the third audio output sound pressure level is unchanged.

0030According to a third aspect of the invention there is provided an apparatus comprising: a safety timer configured to generate a first time period; a state determiner configured to determine a change of state in the apparatus within the first time period, wherein a first state operates with a first audio output having a first average sound pressure level and a second state operates with a second audio output having a higher average sound pressure level; and an audio processor configured to process the second audio output signal such that the second audio output sound pressure level is acoustically continuous with respect to the first average sound pressure level immediately following the change of state.

0031The apparatus may further comprise a muting timer configured to generate a muting time period, wherein the audio processor is configured to mute the second audio output for the muting time period.

0032The apparatus may further comprise an audio ramp timer configured to generate an audio ramp time period, wherein the audio processor is configured to ramp the second audio output for the audio ramp time period.

0033The audio processor may be configured to mute the second audio output for the muting time period and ramp the audio output for the audio ramp time period following the muting time period.

0034The audio processor may comprise a linear ramping amplifier.

0035The audio processor may comprise a non-linear ramping amplifier.

0036The state determiner may comprise: a first state determiner configured to determine the first state is a member of a first group of states; and a second state determiner configured to determine the second state is member of a second group of states.

0037The first group of states may comprise states which operate with the first audio output generated by an earpiece transducer.

0038The first group of states may comprise at least: telecommunication earpiece audio playback.

0039The second group of states may comprise states which operate with the second audio output generated by an integrated handsfree transducer.

0040The second group of states may comprise: integrated handsfree speaker alert tone playback; integrated handsfree speaker music playback; integrated handsfree speaker frequency modulation (FM) radio playback; integrated handsfree speaker digital radio such as DAB (Digital Audio Broadcasting) or DRM (Digital Radio Mondiale) playback; integrated handsfree speaker amplitude modulation (AM) radio playback;integrated handsfree speaker navigation command playback; and integrated handsfree speaker video playback.

0041The apparatus may comprise a maximum sound pressure level estimator configured to determine the maximum value of the higher average sound pressure level is greater than a threshold value; and the audio processor may comprise a sound pressure level limiter configured to limit the maximum value of the higher average sound pressure value to the threshold value.

0042The second state may further operate with a third audio output located physically separate from the first audio output; and the audio processor may comprise a unity gain stage configured to pass the third audio output sound pressure level unchanged.

0043According to a fourth aspect of the invention there is provided a computer-readable medium encoded with instructions that, when executed by a computer perform: determining a change of state in an apparatus within a first time period, wherein a first state operates with a first audio output having a first average sound pressure level and a second state operates with a second audio output having a higher average sound pressure level; and processing the second audio output signal such that the second audio output sound pressure level is acoustically continuous with respect to the first average sound pressure level immediately following the change of state.

0044According to a fifth aspect of the invention there is provided an apparatus comprising: a timing means for generating a first time period; a state determining means for determining a change of state in the apparatus within the first time period, wherein a first state operates with a first audio output having a first average sound pressure level and a second state operates with a second audio output having a higher average sound pressure level; and an audio processor means for processing the second audio output signal such that the second audio output sound pressure level is acoustically continuous with respect to the first average sound pressure level immediately following the change of state.

0045The apparatus may further comprise a muting control means for generating a muting time period, wherein the audio processor means is configured to mute the second audio output for the muting time period.

0046The apparatus may further comprise an ramp control means for generating an audio ramp time period, wherein the audio processor means is configured to ramp the second audio output for the audio ramp time period.

0047The audio processor means may be configured to mute the second audio output for the muting time period and ramp the audio output for the audio ramp time period following the muting time period.

0048The audio processor means may comprise a linear ramping amplifier.

0049The audio processor means may comprise a non-linear ramping amplifier.

0050The state determiner means may comprise: a first state determiner configured to determine the first state is a member of a first group of states; and a second state determiner configured to determine the second state is member of a second group of states.

0051The first group of states may comprise states which operate with the first audio output generated by an earpiece transducer.

0052The first group of states may comprise at least: telecommunication earpiece audio playback.

0053The second group of states may comprise states which operate with the second audio output generated by an integrated handsfree transducer.

0054The second group of states may comprise: integrated handsfree speaker alert tone playback; integrated handsfree speaker music playback; integrated handsfree speaker frequency modulation (FM) radio playback; integrated handsfree speaker digital radio such as DAB (Digital Audio Broadcasting) or DRM (Digital Radio Mondiale) playback; integrated handsfree speaker amplitude modulation (AM) radio playback;integrated handsfree speaker navigation command playback; and integrated handsfree speaker video playback.

0055The apparatus may comprise a sound pressure level estimator means for determining the maximum value of the higher average sound pressure level is greater than a threshold value; and the audio processor means may comprise a sound pressure level limiter configured to limit the maximum value of the higher average sound pressure value to the threshold value.

0056The second state may further operate with a third audio output located physically separate from the first audio output; and the audio processor means may comprise a unity gain stage configured to pass the third audio output sound pressure level unchanged.

0057An electronic device may comprise apparatus as described above.

0058A chipset may comprise apparatus as described above.

BRIEF DESCRIPTION OF DRAWINGS

0059For better understanding of the present invention, reference will now be made by way of example to the accompanying drawings in which:

0060<figref idref="DRAWINGS">FIG. 1</figref> shows schematically an apparatus employing embodiments of the application;

0061<figref idref="DRAWINGS">FIGS. 2</figref><i>a</i>, <b>2</b><i>b</i>, and <b>2</b><i>c </i>show schematically external views of apparatus suitable for implementing some embodiments of the application;

0062<figref idref="DRAWINGS">FIG. 3</figref> shows schematically an example of acoustic shock;

0063<figref idref="DRAWINGS">FIG. 4</figref> shows schematically an acoustic shock prevention apparatus according to some embodiments of the application;

0064<figref idref="DRAWINGS">FIG. 5</figref> shows operation of the acoustic shock prevention apparatus as shown in <figref idref="DRAWINGS">FIG. 4</figref> according to some embodiments of the application;

0065<figref idref="DRAWINGS">FIG. 6</figref> shows the operation of the acoustic shock prevention apparatus on some audio waveforms; and

0066<figref idref="DRAWINGS">FIG. 7</figref> shows schematically an example of acoustic shock prevention.

0067The following describes apparatus and methods for the provision of acoustic shock prevention or mitigation. In this regard reference is first made to <figref idref="DRAWINGS">FIG. 1</figref> which shows a schematic block diagram of an exemplary electronic device <b>10</b> or apparatus, which may incorporate acoustic shock mitigation/prevention apparatus according to some embodiments of the application.

0068The apparatus <b>10</b> may for example be a mobile terminal or user equipment for a wireless communication system. In other embodiments the electronic device may be an audio player such as an mp3 player, or media player such as an mp4player.

0069The apparatus <b>10</b> comprises a processor <b>21</b> which may be linked via a digital-to-analogue converter <b>32</b> to a playback speaker system <b>33</b> configured to provide a suitable audio playback. The playback speaker system <b>33</b> in some embodiments can comprise at least one suitable loudspeaker or transducer configured to operate in an earpiece mode. In other words generating acoustic waves suitable when the apparatus is located adjacent to or in contact with the ear. Furthermore at least one of the at least one loudspeaker is configured to operate in an integrated handsfree (IHF) mode. In other words suitable for generating acoustic waves when the apparatus is used when the apparatus is not in close proximity to the ear. In some embodiments the playback speaker can further be a headphone or ear worn speaker (EWS) set. In some embodiments the apparatus <b>10</b> may comprise a headphone connector for receiving a headphone or headset. The processor <b>21</b> is in some embodiments further linked to a transceiver (TX/RX) <b>13</b>, to a user interface (UI) <b>15</b> and to a memory <b>22</b>.

0070The processor <b>21</b> may be configured to execute various program codes. The implemented program codes in such embodiments comprise an acoustic shock prevention code or codes. The implemented program codes <b>23</b> in some embodiments can be stored for example in the memory <b>22</b> for retrieval by the processor <b>21</b> whenever needed. The memory <b>22</b> could further provide a section <b>24</b> for storing data, for example data that has been processed in accordance with the embodiments.

0071The acoustic shock prevention code or operations can in some embodiments be implemented in hardware or firmware. In the following example a schematic hardware implementation is described however it would be understood that various program codes, stored for example in memory <b>22</b>, can also implement the acoustic shock prevention operations.

0072The user interface <b>15</b> in some embodiments enables a user to input commands to the electronic device <b>10</b>, for example via a keypad, and/or to obtain information from the electronic device <b>10</b>, for example via a display. The transceiver <b>13</b> enables a communication with other electronic devices, for example via a wireless communication network.

0073It is to be understood again that the structure of the electronic device <b>10</b> could be supplemented and varied in many ways.

0074The apparatus <b>10</b> can in some embodiments further comprise at least one microphone <b>11</b> for monitoring audio or speech. The apparatus <b>10</b> in such embodiments may further comprise an analogue-to-digital converter <b>14</b> configured to convert the input analogue audio signal into a digital audio signal and provide the digital audio signal to the processor <b>21</b>.

0075The apparatus <b>10</b> can in some embodiments receive a bit stream via the transceiver <b>13</b>. The processor <b>21</b> in these embodiments may process the received audio signal data, and output the audio.

0076In some embodiments the headphone connector can be configured to communicate to a headphone set or earplugs wirelessly, for example by a Bluetooth profile, or using a conventional wired connection.

0077The received stereo audio data can in some embodiments also be stored, instead of presented immediately, in the data section <b>24</b> of the memory <b>22</b>, for instance for later presentation or forwarding to still another electronic device.

0078It would be appreciated that the schematic structures described in <figref idref="DRAWINGS">FIGS. 2</figref><i>a</i>, <b>2</b><i>b</i>, <b>2</b><i>c </i>and <b>4</b> and the method steps shown in <figref idref="DRAWINGS">FIG. 5</figref> represent only a part of the operation of an apparatus suitable for implementing the functionality of the complete device.

0079With respect to <figref idref="DRAWINGS">FIG. 2</figref><i>a</i>, an external view of a first example of apparatus suitable for implementing embodiments of the application is shown. The apparatus <b>10</b> is shown with a display screen <b>112</b> which in some embodiments is suitable for providing user interface input and display capabilities and further configured to be connected to the processor which in some embodiments controls both displaying information using the display screen <b>112</b> and determines when input to the device <b>10</b> has been made using the display screen <b>112</b>. The device <b>10</b> further comprises in some embodiments physical buttons <b>101</b> suitable for providing a physical user interface experience such as making and ending a telephone call. The device <b>10</b> in some embodiments as shown in <figref idref="DRAWINGS">FIG. 2</figref><i>a </i>can further comprise a multifunction device component <b>115</b>. The multifunction device component <b>115</b> can for example be used both as an integrated handsfree (IHF) speaker <b>118</b> and earpiece speaker <b>120</b>.

0080With respect to <figref idref="DRAWINGS">FIG. 2</figref><i>b </i>an external view of a further example device or apparatus <b>10</b> suitable for implementing embodiments is shown. In this second example the multifunction device <b>115</b> as shown in <figref idref="DRAWINGS">FIG. 2</figref><i>a </i>is replaced by a separate but physically closely located mono-channel integrated handsfree speaker <b>118</b> suitable for providing an audio output for handsfree operations and an earpiece speaker <b>120</b> suitable for providing outputs via an earpiece port to the user.

0081With respect to <figref idref="DRAWINGS">FIG. 2</figref><i>c </i>an external view of a third example apparatus <b>10</b> is shown. In the example shown in <figref idref="DRAWINGS">FIG. 2</figref><i>c </i>the multifunction device component <b>115</b> shown in <figref idref="DRAWINGS">FIG. 2</figref><i>a </i>is replaced by separate but physically closely located first or left channel integrated handsfree speaker <b>117</b> suitable for providing an audio output for handsfree operations as the left audio channel and an earpiece speaker <b>120</b> suitable for providing audio output for earpiece operations. Furthermore in the example shown in <figref idref="DRAWINGS">FIG. 2</figref><i>c</i>, the apparatus or device <b>10</b> comprises a second or right channel integrated handsfree (IHF) speaker <b>119</b> suitable for providing an audio output for handsfree operations as the right audio channel. Thus the apparatus shown in <figref idref="DRAWINGS">FIG. 2</figref><i>c </i>is suitable for producing stereo effect audio outputs using the left and right channel integrated handsfree speakers. In other words the example shown in <figref idref="DRAWINGS">FIG. 2</figref><i>c </i>can output a left channel audio signal via the IHF left speaker <b>117</b> and a right channel audio signal via the right IHF speaker <b>119</b>.

0082With respect to <figref idref="DRAWINGS">FIG. 4</figref> an acoustic shock prevention apparatus according to some embodiments is shown in further detail. The operation of the acoustic shock prevention apparatus according to these embodiments is furthermore described with respect to <figref idref="DRAWINGS">FIG. 5</figref>. It would be appreciated that in some embodiments the operations performed by the acoustic shock prevention apparatus as described in the following sections could be implemented at least partially as code operations, modules or separate programs configured to run on at least one processor and stored in at least one memory as described above. In some other embodiments the operations could be implemented at least partially as separate or partially divided physical hardware components. In some embodiments the operations and components described below can be implemented as firmware elements.

0083The acoustic shock prevention apparatus in some embodiments comprises an apparatus state monitor <b>301</b> which is configured to monitor the current state or mode of operation of the apparatus or device <b>10</b>. In some embodiments the apparatus state monitor <b>301</b>, state determiner or suitable state determining means, is capable of determining such modes or states as; earpiece phone call mode, integrated handsfree speaker alert tone mode, music playback over integrated handsfree speaker mode, frequency modulation (FM) radio playback over integrated handsfree speaker mode, integrated handsfree speaker digital radio such as DAB (Digital Audio Broadcasting) or DRM (Digital Radio Mondiale) playback, integrated handsfree speaker amplitude modulation (AM) radio playback, car navigation command output over integrated handsfree speaker mode, and video playback over integrated handsfree speaker mode. In some embodiments the phone state monitor <b>301</b> is configured to determine between modes or states dependent on whether that operate an earpiece (or headphone) mode and an integrated handsfree state or mode.

0084In such embodiments the apparatus state monitor <b>301</b> is therefore capable of, or configured to, determine when the apparatus <b>10</b> is in an earpiece mode and likely to be located close to the user and when the apparatus <b>10</b> is in an integrated handsfree speaker mode and likely to be located at a distance from the user. These modes may be activated or controlled by the processor when the user is using the apparatus <b>10</b>.

0085In some embodiments the apparatus state monitor <b>301</b> when determining a change in the state or mode of operation of the apparatus <b>10</b> such as described above the apparatus state monitor can trigger an output to a safety timer <b>303</b>. In some embodiments the safety timer <b>303</b> is triggered when the phone state monitor <b>301</b> determines an earpiece mode or state ending.

0086In some embodiments the safety timer <b>303</b> is triggered when the phone state monitor <b>301</b> determines an ending or closing of a mode from a first or ‘watch’ list of modes stored in the memory of the apparatus. This first list of modes in some embodiments can be configured by at least one of the operator, the user or an application or control entity operating the mode. For example in some embodiments an application when being installed on the apparatus can request that the mode be appended to the first list as it is expected that the user will operate the application with the device close to the user.

0087The determination of the change in the apparatus state is shown in <figref idref="DRAWINGS">FIG. 5</figref> by step <b>401</b>.

0088The acoustic shock prevention apparatus further comprises a safety timer <b>303</b> which on receiving a first activation signal from the apparatus state monitor <b>301</b> performs a timer operation. In some embodiments the timer operation period can be 2 seconds; however it would be appreciated that the safety timer period can be less than or greater than 2 seconds. The safety timer <b>303</b> can be implemented by any suitable timing means for generating a first timing period.

0089In some embodiments the safety timer operation period can be configurable and be any suitable time. In some embodiments the safety timer operation period can be configured by the user of the device, for example within the settings of the apparatus. In some other embodiments the safety timer operation period can be configured by the manufacturer or operator of the device <b>10</b> such that the timer allows sufficient time for the user to remove the apparatus from their ear in order to prevent acoustic shock.

0090The apparatus state monitor <b>301</b> further monitors the state of the apparatus while the safety timer period is active.

0091The operation of starting the safety timer and continued monitoring of the apparatus state during the safety timer period is shown in step <b>403</b>.

0092Where the apparatus state monitor <b>301</b> determines that there is an apparatus state change during the timer period the apparatus state monitor <b>301</b> can activate the muting timer <b>305</b> and the audio ramp timer <b>307</b> which provide inputs to the audio subsystem controller <b>309</b>.

0093In some embodiments the apparatus state monitor <b>301</b> is configured to activate at least one of the muting timer <b>305</b> and audio ramp timer <b>307</b> when determining an apparatus state change to a state of mode of operation from a second or ‘danger’ list of modes stored in the memory of the apparatus. This second list of modes in some embodiments can be configured by at least one of the operator, the user or an application or control entity operating the mode. For example in some embodiments an application when being installed on the apparatus can request that the mode be appended to the first list as it is expected that the user will operate the application using the integrated handsfree speaker at sound pressure levels capable of causing acoustic shock to the user.

0094Thus for example when the apparatus state monitor <b>301</b> determines an ending of a state or mode of earpiece phone call mode, which can be on the first list and then within the safety time period determines a start of a further call or re-entering the earpiece phone call, which is not on the second list then the apparatus state monitor <b>301</b> can maintain monitoring the phone stare to determine when the earpiece phone call mode is ended and re-start the safety timer <b>303</b> again.

0095Where the safety timer period expires without the apparatus state monitor <b>301</b> determining an apparatus state change (or state that occurs on the second list) the apparatus state monitor <b>301</b> can maintain monitoring the phone state to determine a suitable state end to start the safety timer again. In other words as shown in <figref idref="DRAWINGS">FIG. 5</figref> the operation passes back to step <b>401</b>.

0096The acoustic shock prevention apparatus furthermore in some embodiments comprises a muting timer <b>305</b> configured to provide a signal over a defined or configurable period to an audio subsystem controller. In other words the apparatus may comprise a muting control means configured to generate a muting time period which defines a time period for an audio subsystem controller <b>309</b> to process and mute the audio output over. The muting timer <b>305</b> on receiving an activation signal from the apparatus state monitor <b>301</b> in some embodiments provides the signal output to the audio subsystem controller <b>309</b> as an interrupt signal controlling the audio subsystem controller <b>309</b> to mute the integrated handsfree speaker closest to the earpiece for the muting timer period.

0097The acoustic shock prevention apparatus in some embodiments comprises an audio subsystem controller <b>309</b> which is configured to receive output audio signals to be presented to the user via the earpieces, headsets and integrated handsfree speaker or speakers. In other words the apparatus can comprise an audio processor means for processing the audio signal, for example to mute the audio signal over the period defined by the muting control means. The audio subsystem controller <b>309</b> in some embodiments can be a gain stage of an audio subsystem controlled via a series of inputs such as a muting timer input and an audio ramp timer input. The audio subsystem controller <b>309</b> on receiving a muting timer input can set the audio subsystem gain value to 0, in other words mute the signal to be output by the integrated handsfree speaker. In some embodiments the audio subsystem <b>309</b> is configured to mute the signal to be output by the integrated handsfree speaker closest to the earpiece speaker for the time period defined by the muting timer <b>305</b>. In some embodiments where the apparatus comprises more than one earpiece speaker the audio subsystem <b>309</b> can determine which of the earpiece speakers is the closest to the user. For example in some embodiments the apparatus can further comprise a proximity sensor located by each of the earpiece speakers and capable of providing the audio subsystem <b>309</b> with the information required to mute the integrated handsfree speaker closest to the earpiece which had been used.

0098The muting time period generated by the muting timer <b>305</b> can be any suitable timer period. For example as shown in <figref idref="DRAWINGS">FIG. 6</figref> a muting time period can be approximately 1.5 seconds. In some embodiments the muting time period can be configurable and be configured by at least one of the user of the apparatus, by the network operator, by the apparatus manufacturer and by the an application of program designer of an application which invokes or generates a mode or state.

0099The operation starting of the muting timer and the muting the speaker closest to the earpiece for the muting timer period is shown in <figref idref="DRAWINGS">FIG. 5</figref> by step <b>405</b>.

0100In some embodiments the acoustic shock prevention apparatus further comprises an audio ramp timer <b>307</b>. The audio ramp timer <b>307</b> in some embodiments can be configured to receive an input from the apparatus state monitor <b>301</b> and also in some embodiments receive the output of the muting timer <b>305</b>. In other words the apparatus can in some embodiments comprise a ramp control means for generating an audio ramp time period. In such embodiments the audio processor means for processing the audio signal can ramp the audio signal over the period defined by the ramp control means. When the audio ramp timer <b>307</b> is activated either directly from the apparatus state monitor <b>301</b> or indirectly from the audio muting timer <b>305</b> by determining an activation and subsequent deactivation of the muting timer period signal then the audio ramp timer <b>307</b> may provide an audio ramping timer input to the audio subsystem controller <b>309</b>. In some embodiments the time period defined by the audio ramp timer can run concurrently with the time period defined by the muting timer <b>305</b>, and the time period defined by the audio ramp timer <b>307</b> is greater than the time period defined by the muting timer <b>305</b>. In some further embodiments the audio ramp timer <b>307</b> provides an audio ramping timer input to the audio subsystem controller <b>309</b> subsequent to the muting timer <b>305</b> providing the muting timing input signal.

0101The audio ramp time period generated by the audio ramp timer <b>307</b> can be any suitable timer period. For example as shown in <figref idref="DRAWINGS">FIG. 6</figref> an audio ramp time period can be approximately 7 seconds. In some embodiments the audio ramp time period can be configurable and be configured by at least one of the user of the apparatus, by the network operator, by the apparatus manufacturer and by the an application of program designer of an application which invokes or generates a mode or state.

0102Furthermore in some embodiments both the muting timer <b>305</b> operations and the audio ramp timer <b>307</b> operations are implemented in a programmable single timer which is configured to indicate a start signal; an end of muting signal and an end of audio ramping signal to indicate a start to audio processing; an end of muting and an end of audio ramping respectively and thus implicitly define a muting time period and audio ramping time period.

0103The audio system controller <b>309</b> in some embodiments on receiving the audio ramp timer <b>307</b> signal can then apply a ramp function to the gain stage to control the audio acoustic signal generated by the speaker closest to the earpiece over the audio ramp period <b>407</b>. The ramp function applied to the gain stage can be any suitable monotonically increasing function.

0104The operation of starting the audio ramp timer and applying the ramp function to the speaker closest to the earpiece over the audio ramp period is shown in <figref idref="DRAWINGS">FIG. 5</figref> by step <b>407</b>.

0105With respect to <figref idref="DRAWINGS">FIG. 6</figref> an example of the operation of the acoustic shock prevention apparatus is shown with regards to a first and second channel acoustic signal. The first channel representation <b>501</b> which for example may be a right channel of the integrated handsfree device (which for example in <figref idref="DRAWINGS">FIG. 2</figref><i>c </i>is the integrated handsfree speaker not adjacent to the earpiece) shows a phone call earpiece mode ending at time sample <b>0</b> and an audio signal generated using audio from the ‘incoming call’ <b>509</b> integrated handsfree alert mode approximately 2 seconds later. This integrated handsfree alert mode, if implemented at high sound pressure levels close to the earpiece, could cause acoustic shock. However as shown in the second channel representation <b>503</b> embodiments of the application mitigate or prevent acoustic shock from occurring.

0106With respect to the second channel representation <b>503</b> the phone call earpiece mode ends at time sample 0 <b>505</b>. This triggers the start of the safety timer <b>303</b>, which is running during the period shown the ‘algorithm running’ label time <b>507</b>. The new ‘incoming call’ integrated handsfree alert mode <b>509</b> (which can also be in other examples an audio handsfree playback, FM Radio playback over integrated handsfree, integrated handsfree speaker digital radio such as DAB (Digital Audio Broadcasting) or DRM (Digital Radio Mondiale) playback, integrated handsfree speaker amplitude modulation (AM) radio playback, video playback over integrated handsfree or any handsfree playback mode) is detected. In other words the apparatus state monitor <b>301</b> in this example determines a change in state or mode of operation of the apparatus during the safety timer period.

0107The change in state causes, according to this example, the apparatus state monitor <b>301</b> to activate the muting timer <b>305</b> from when the new ‘incoming call’ mode is detected at time labelled <b>509</b> for the period from when the muting timer is activated <b>511</b> to when the muting timer is deactivated <b>513</b>. In the example shown in <figref idref="DRAWINGS">FIG. 6</figref> the muting time period is approximately 1.5 seconds. However it would be appreciated that the muting time period is configurable to any suitable time period. This in <figref idref="DRAWINGS">FIG. 6</figref> is shown as the audio signal difference between the first channel representation <b>501</b> and the second channel representation <b>503</b> for the audio signal of the incoming call alert as the integrated handsfree speaker signal is muted for the second channel representation <b>503</b> when compared to the first channel representation <b>501</b>.

0108The time instance when the muting timing period expires <b>513</b> is then followed by the ramping timer period when there is an application of a ramping function to the audio signal closest to the earpiece when compared to the first channel. As such the application of the ramping function to the audio signal can be seen in <figref idref="DRAWINGS">FIG. 6</figref> from the end of the muting period <b>513</b> to the time <b>515</b> when the volume level of the full first channel representation <b>501</b> audio signal is also seen in the second channel representation <b>503</b> audio signal. <figref idref="DRAWINGS">FIG. 6</figref> the audio ramp period is approximately 7 seconds. However it would be appreciated that the audio ramp time period is configurable to be set to any suitable time period.

0109Thus according to some embodiments there the apparatus is capable of maintaining an acoustic continuity between changes of use cases which would reduce the possibility of acoustic shock.

0110The example of the acoustic shock prevention is also shown in <figref idref="DRAWINGS">FIG. 7</figref> which shows a schematic view similar to that shown in <figref idref="DRAWINGS">FIG. 3</figref> except that the acoustic signal produced by the first integrated handsfree speaker <b>117</b> shown by the signal <b>605</b> is first muted and then ramped as can be seen in the waveform <b>601</b>.

0111In some embodiments the ramping up of the audio signal from a safe level or from a muted state with a well defined increase rate allows the ramping of the volume level to a maximum of 136 dB peak/131 dBa. This in embodiments prevents acoustic shock but also enables the user to recognise the audio signal, for example an incoming phone call, resuming music or FM radio playback. Furthermore as the audio signal is ramped the user could automatically remove the phone from being close to the ear.

0112In some embodiments the apparatus state monitor <b>301</b> can further implement acoustic shock management based on determining the maximum sound pressure limit of the signal to be played. In other words the apparatus can in some embodiments comprise a sound pressure level estimator or sound pressure level estimator means for determining the maximum or peak value of the higher average sound pressure level. In such embodiments where the apparatus state monitor <b>301</b> determines that the maximum sound pressure limit for the incoming signal the integrated loudspeaker signal is 118 dBA then no time period is applied, in other words the phone state monitor <b>301</b> does not trigger either the muting timer or audio ramp timer and the signal output IHF mode is not modified.

0113In some other embodiments the apparatus state monitor <b>301</b>, when detecting a maximum sound pressure limit of 125 dBA in the signal to be output on the IHF speaker, further determines if the audio signal to be output is a continuous or non-continuous signal. In these circumstances the apparatus state monitor <b>301</b> triggers the muting timer and audio ramp timer such that the muting timer is activated for both continuous and non-continuous signals. In some further embodiments the apparatus state monitor <b>301</b> furthermore for continuous signals, such as ring tones and music, does not activate the ramp timer and so the audio sub-system permits the signals to be output after the muting period at the sound pressure level which is determined by the state or mode only. For non-continuous signals such as voice the apparatus state monitor <b>301</b> can in there embodiments activate the audio ramp timer <b>307</b> which controls the audio subsystem to increase the sound pressure levels to their full value over the audio ramp time period.

0114Furthermore in some embodiments the apparatus state monitor <b>301</b> when determining that the maximum sound pressure level on the incoming mode signal is 136 dB peak or 131 dBA activates both the muting and audio ramp timers.

0115Furthermore the audio ramp timer <b>307</b> in some embodiments can be configured to send a further control signal to the audio subsystem controller <b>309</b> such that no operating mode or signal failure exceeds the 136 db peak limit and thus prevent hearing damage and/or transducer damage even after the ramp time period has expired.

0116Thus in summary at least one embodiment of the application performs a method comprising determining a change of state in an apparatus within a first time period, wherein a first state operates with a first audio output having a first average sound pressure level and a second state operates with a second audio output having a higher average sound pressure level; and processing the second audio output signal such that the second audio output sound pressure level is acoustically continuous with respect to the first average sound pressure level immediately following the change of state.

0117Although the above examples describe embodiments of the invention operating within an electronic device <b>10</b> or apparatus, it would be appreciated that the invention as described below may be implemented as part of any audio processor. Thus, for example, embodiments of the invention may be implemented in an audio processor which may implement audio processing over fixed or wired communication paths.

0118Thus user equipment may comprise an audio processor such as those described in embodiments of the invention above.

0119It shall be appreciated that the term electronic device and user equipment is intended to cover any suitable type of wireless user equipment, such as mobile telephones, portable data processing devices, audio players (also known as MP3 players), media players (also known as MP4 players) or portable web browsers.

0120In general, the various embodiments of the invention may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

0121Thus at least some embodiments may be an apparatus comprising at least one processor and at least one memory including computer program code the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: determining a change of state in an apparatus within a first time period, wherein a first state operates with a first audio output having a first average sound pressure level and a second state operates with a second audio output having a higher average sound pressure level; and processing the second audio output signal such that the second audio output sound pressure level is acoustically continuous with respect to the first average sound pressure level immediately following the change of state.

0122The embodiments of this invention may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.

0123Thus at least some embodiments may be a computer-readable medium encoded with instructions that, when executed by a computer perform: determining a change of state in an apparatus within a first time period, wherein a first state operates with a first audio output having a first average sound pressure level and a second state operates with a second audio output having a higher average sound pressure level; and processing the second audio output signal such that the second audio output sound pressure level is acoustically continuous with respect to the first average sound pressure level immediately following the change of state.

0124The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi-core processor architecture, as non-limiting examples.

0125Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

0126Programs, such as those provided by Synopsys, Inc. of Mountain View, Calif. and Cadence Design, of San Jose, Calif. automatically route conductors and locate components on a semiconductor chip using well established rules of design as well as libraries of pre-stored design modules. Once the design for a semiconductor circuit has been completed, the resultant design, in a standardized electronic format (e.g., Opus, GDSII, or the like) may be transmitted to a semiconductor fabrication facility or “fab” for fabrication.

0127As used in this application, the term ‘circuitry’ refers to all of the following: <ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0000"><ul id="ul0002" list-style="none"><li id="ul0002-0001" num="0128">(a) hardware-only circuit implementations (such as implementations in only analogue and/or digital circuitry) and</li><li id="ul0002-0002" num="0129">(b) to combinations of circuits and software (and/or firmware), such as: (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions and</li><li id="ul0002-0003" num="0130">(c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.</li></ul></li></ul>

0131This definition of ‘circuitry’ applies to all uses of this term in this application, including any claims. As a further example, as used in this application, the term ‘circuitry’ would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term ‘circuitry’ would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or similar integrated circuit in server, a cellular network device, or other network device.

0132The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the exemplary embodiment of this invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of this invention as defined in the appended claims.