WO2024253650A1

WO2024253650A1 - Audio limiter for controlling battery life

Info

Publication number: WO2024253650A1
Application number: PCT/US2023/024741
Authority: WO
Inventors: Kevin J. Bastyr; Kadagattur Gopinatha Srinidhi; Srinath Arunachalam; John Combs
Original assignee: Harman International Industries Inc
Current assignee: Harman International Industries Inc
Priority date: 2023-06-07
Filing date: 2023-06-07
Publication date: 2024-12-12
Anticipated expiration: 2025-12-07

Abstract

Techniques for managing power consumption of an audio device include detecting that a power consumption of the audio device is above a target power consumption level; in response to detecting that the power consumption of the audio device is above the target power consumption level: ramping down a gain of the audio device; accumulating an amount of the power consumption of the audio device that is above the target power consumption level to generate an accumulated excess power consumption of the audio device; computing a gain profile to compensate for the accumulated excess power consumption; and controlling the gain of the audio device based on the gain profile.

Description

AUDIO LIMITER FOR CONTROLLING BATTERY LIFE

BACKGROUND

Field of the Various Embodiments

[0001] Embodiments of the present disclosure relate generally to techniques for controlling battery life in portable audio devices.

Description of the Related Art

[0002] In a typical audio system, the speaker and amplifier are the components that limit the maximum audio playback level or volume of an audio system. When amplifiers reach their output limit, the audio signal is “hard-clipped” and severe audible distortion results. A soft- clipping limiter is generally used to prevent the severe distortion of hard clipping by replacing the severe distortion with a less harsh sounding soft clipping that causes less distortion.

[0003] Distortion can also occur in a speaker when the speaker is played at very high levels due to hard bottoming and suspension pull-up in the physical components of the speaker (i.e. the spider and/or surround). Hard bottoming occurs when the bobbin in the voice coil strikes the back plate and a loud metallic striking sound results. Suspension pull-up occurs when the suspension becomes stiffer at the edges of the range of motion of the cone and is characterized by nonlinear behaviors such as undesirable additional harmonic generation. Hard bottoming and suspension pull-up can be reduced or eliminated by using hard clipping or soft clipping, but at the expense of introducing the unwanted distortions due to the use of these conventional clipping or limiting techniques.

[0004] An important performance metric for any portable audio device is battery life. The battery life of a portable audio device is directly impacted by the audio playback level and duration at which sounds are played on the portable audio device. The higher the audio playback level at which an audio signal is rendered, the more power that is consumed and the shorter the battery life of the portable audio device. The audio playback level of an audio device, and thus its power consumption, can be controlled by the output section of the audio device, which consists primarily of the amplifier and accompanying signal processing that drives the speaker. To help protect the amplifier and the speaker, the audio device also includes signal processing in the form of an audio limiter, such as a conventional hard clipping or soft clipping limiter. However, as noted above hard clipping and soft clipping limiters introduce undesirable distortions to the audio generated by an audio device using one of the limiters. [0005] As the foregoing illustrates, what is needed in the art are more effective techniques for limiting the audio playback level of audio devices without introducing these audible distortions that can be objectionable to listeners.

SUMMARY

[0006] One embodiment of the present disclosure sets forth a computer-implemented method for managing power consumption of an audio device. The method includes detecting that a power consumption of the audio device is above a target power consumption level. The method further includes, in response to detecting that the power consumption of the audio device is above the target power consumption level, ramping down a gain of the audio device to reduce the level of the audio playback and accumulating an amount of the power consumption of the audio device that is above the target power consumption level to generate an accumulated excess power consumption of the audio device. The method also includes computing a gain profile to compensate for the accumulated excess power consumption and controlling the gain of the audio device based on the gain profile.

[0007] Further embodiments provide, among other things, one or more non-transitory computer-readable storage media for storing instructions for implementing the method set forth above, as well as an audio device, such as a toy -based audio device, configured to implement the method set forth above.

[0008] At least one technical advantage of the disclosed techniques relative to the prior art is that, with the disclosed techniques, audio output is managed based on a target life for a battery in an audio device. The disclosed techniques additionally allow the target life of the battery to be achieved even when the audio device periodically outputs sounds that require the output section of the audio output device to consume an amount of power that exceeds a baseline target level allotted to the output section. In addition, the described techniques do not induce the typical audio distortions that occur when using conventional audio limiters. The technical advantages provide one or more technological advancements over prior art approaches.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] So that the manner in which the above recited features of the various embodiments can be understood in detail, a more particular description of the inventive concepts, briefly summarized above, may be had by reference to various embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of the inventive concepts and are therefore not to be considered limiting of scope in any way, and that there are other equally effective embodiments.

[0010] FIG. 1 illustrates a block diagram of an audio device, according to one or more aspects of the various embodiments;

[0011] FIG. 2 illustrates a signal flow diagram of the audio signal flow portion of the audio device of FIG. 1, according to one or more aspects of the various embodiments;

[0012] FIG. 3 illustrates the effects of limiting an audio signal using various techniques;

[0013] FIG. 4 illustrates the depletion characteristics of various battery technologies;

[0014] FIG. 5 illustrates the accumulated energy consumption in response to the audio signal of FIG. 3 without the use of a limiter;

[0015] FIG. 6 illustrates the accumulated energy consumption in response to the audio signal of FIG. 3 where a conventional limiter is used;

[0016] FIG. 7 illustrates the accumulated energy consumption in response to the audio signal of FIG. 3 where a slow-acting limiter is used, according to one or more aspects of the various embodiments;

[0017] FIG. 8 illustrates another gain profile of a slow-acting limiter for the audio signal of FIG. 3, according to one or more aspects of the various embodiments;

[0018] FIG. 9 illustrates another audio signal and the accumulated energy consumption when a limiter is not applied to the audio signal;

[0019] FIG. 10 illustrates the accumulated energy consumption where a slow-acting limiter is used in response to another audio signal of FIG. 9, according to one or more aspects of the various embodiments;

[0020] FIG. 11 illustrates another gain profile of the slow-acting limiter for the another audio signal of FIG. 9, according to one or more aspects of the various embodiments; and

[0021] FIG. 12 illustrates the flow diagram for a method of limiting an audio signal using a slow-acting limiter, according to one or more aspects of the various embodiments.

DETAILED DESCRIPTION

[0022] In the following description, numerous specific details are set forth to provide a more thorough understanding of the various embodiments. However, it will be apparent to one of skilled in the art that the inventive concepts may be practiced without one or more of these specific details.

System Overview

[0023] FIG. 1 illustrates a block diagram of an audio device 100 according to one or more aspects of the various embodiments. As shown, the audio device 100 includes, without limitation, one or more processing unit(s) 102, one or more communications interface(s) 104, one or more secondary storage component(s) 106, one or more user interface component(s) 108, memory 110, output section 116, and one or more batteries 126. Memory 110 stores, without limitation, a signal generator 112 and a slow-acting limiter 114. Output section 116 includes, without limitation, an amplifier 120, and a speaker 122. And although the audio device 100 is described below as a battery-powered audio device, the techniques described herein are applicable to any type of audio device, including audio devices powered by AC power. In an exemplary first embodiment, examples of an audio device 100 include, without limitation, BLUETOOTH® speakers, BLUETOOTH® headphones, media players, smartphones, tablets, interactive electronic devices, and the like.

[0024] In an exemplary second embodiment, examples of an audio device 100 include, without limitation, modular toys, interactive toys, and/or the like, such as action figures, dolls, stuffed animals, vehicles, and the like.

[0025] Processing unit(s) 102 and memory 110 can be implemented in any technically feasible fashion. For example, and without limitation, in various embodiments, any combination of processing unit(s) 102 and memory 110 can be implemented as a stand-alone chip or as part of a more comprehensive solution that is implemented as an applicationspecific integrated circuit (ASIC), a system-on-a-chip (SoC), and/or the like. The one or more processing unit(s) 102 can include any suitable processor, such as a central processing unit (CPU), a digital signal processor (DSP), a graphics processing unit (GPU), an applicationspecific integrated circuit (ASIC), a field programmable gate array (FPGA), a tensor processing unit (TPU), a microprocessor (e.g. ARM M4), any other type of processing unit, or a combination of multiple processing units, such as a CPU configured to operate in conjunction with a GPU. In general, each of the one or more processing unit(s) 102 can be any technically feasible hardware unit capable of processing data and/or executing software applications and modules that are used to manage and control audio device 100. Processing unit(s) 102 are communicatively coupled with communications interface(s) 104, secondary storage component(s) 106, user interface component(s) 108, memory 110, and output section 116 via one or more interconnectors or buses 118.

[0026] In an embodiment, the processing unit(s) 102 is a digital signal processor, and the signal generator 112 and slow-acting limiter 114 are implemented in software and stored in the memory 110 for execution by the processing unit(s) 102. However, the present disclosure is not limited thereto. The aforementioned modules can be implemented in software, hardware, or a combination thereof. The audio signal output from signal generator 112 can take the form of recorded waveforms and/or can be synthesized using various techniques. The techniques can also be used in any combination. Recorded waveforms are audio recordings such as music or podcasts that are stored using various file formats and encoding techniques, including, pcm, .wav, .aiff, .mp3, and the like, or they can be transmitted to audio device 100 via the communication interface 104 or the like. Synthesis (or synthesized signals) refers to creating audio signals using various algorithmic techniques such as subtractive synthesis, FM synthesis, wavetable synthesis, granular synthesis, or any of the synthesis techniques described in U.S. patent application Ser. No. 16/958,950, entitled ADVANCED AUDIO PROCESSING SYSTEM, filed on Jun. 29, 2020, which is hereby incorporated by reference in its entirety, and the like.

[0027] The slow-acting limiter 114 conditions the signal from the signal generator 112 to manage power consumption of an audio device 100. In some embodiments, the slow-acting limiter 114 and signal generator 112 are software based and stored in memory 110. In some embodiments, the slow-acting limiter 114 and signal generator 112 are implemented as part of the processing units. Different implementations are possible and remain in the scope of the present disclosure. The power consumption of the output section 116 of the audio device 100 is monitored to detect when actual power consumption exceeds a target power consumption. The target power consumption is determined based on the battery life goal of the audio device 100. The actual power consumption can be determined by monitoring the voltage across the terminals of speaker 122, by monitoring the current and voltage output by amplifier 120 or sent to speaker 122, by monitoring the current consumed by output amplifier 120, or by monitoring the current drain from the one or more batteries 126. Other functionally equivalent, standard methods of measuring or estimating current consumption or power consumption are known to those of ordinary skill in the art. Upon determining that the actual power consumption exceeds the target power consumption, an optional attack delay is applied. At the end of the attack delay, the slow-acting limiter 114 begins the slow ramp down of the gain of the amplifier 120. In an alternate embodiment, slow-acting limiter 114 acts on the gain of an additional or alternate amplification stage in the signal flow proceeding or following amplifier 120. The slow acting limiter 114 continues to monitor the power consumption of the output section 116 of the audio device 100 to detect when the actual power consumption drops below the target power consumption. Until the actual power consumption drops below the target power consumption, the excess power consumed by the output section 116 is accumulated by the slow-acting limiter 114. Upon the actual power consumption dropping below the target power consumption, the slow-acting limiter 114 computes a gain profile based on the accumulated excess power consumption. The gain profile includes a ramp down period, recovery period, and ramp up period and is chosen to recover the excess power consumed during the period when the power consumption of the output section 116 was above the target power consumption. The ramp up and ramp down in the gain of the amplifier 120 occurs over a time period that is long enough so that changes in the volume of the audio signal output by the speaker 122 are not easily detected by a listener, (e.g., the rates for ramping down and ramping up of the gain 240 are selected to reduce a likelihood that changes in the gain 240 due to the ramping down and ramping up of the gain are detected by a user). The slow-acting limiter 114 controls the gain of the amplifier 120 based on the gain profile. In some embodiments, the slow ramp down and slow ramp up is set between 3 seconds and 9 seconds, inclusive, such as 6 (the slow ramp down time and slow ramp up time need not be the same). For some gain changes below six seconds, the result of the slow-acting limiter 114 can become audible. Above six seconds, the probability of recovering from the excess battery drain from a first overage before a second overage occurs is reduced. In some embodiments, the value of the slow ramp down time and slow ramp up time can include a portion of the recovery time.

[0028] The audio device 100 also includes communication interface(s) 104, enabling the audio device 100 to connect to other devices. For example, the communications interface(s) 104 is a local wireless interface, such as a wireless interface operating according to one of the suite of IEEE 802.11 standards, BLUETOOTH®, Apple Airplay, Google Chromecast, or the like. However, the present disclosure is not limited thereto. For example, the communication interface(s) 104, enable the audio device 100 to connect to media content services through a network such as the internet, connect to media players, additional speakers other than speaker 122, and the like.

[0029] Recorded waveforms can also be received at the audio device 100 via communications interface(s) 104 from another device or a media content service. Examples of media content service(s) include Spotify, Apple Music, Pandora, YouTube Music, Amazon Music, Tidal, Deezer, and/or the like. Media or media content, as used herein, includes, without limitation, audio content (e.g., spoken and/or musical audio content, audio content files, streaming audio content, audio track of a video, and/or the like) and/or video content. Examples of media content service(s) include, without limitation, media content streaming services, digital media content sellers, media servers (local and/or remote), and/or the like. More generally, media content services include one or more computer systems (e.g., a server, a cloud computing system, a networked computing system, a distributed computing system, etc.) for storing and distributing media content. Audio device 100 can communicatively couple with media content service(s) via network(s) and download and/or stream media content from media content services. In one embodiment, communications interface 104 can contain an input jack such that analog or digital signals can be input to audio device 100 using a wired connection to a secondary device such as a Google Chromecast Audio device, a Google Chromecast device, an Apple Airplay device, another computer, tablet, media storage device, etc.

[0030] The audio device 100 includes one or more secondary storage component(s) 106. The secondary storage component(s) 106 are digital data storage components such as, for example, fixed or removable disk drives, solid state drives, secure digital and other flash memory devices, and CD-ROM, DVD-ROM, Blu-Ray, HD-DVD, or other magnetic, optical, solid state storage devices, powered or passive RFID tags and/or the like. However, the present invention is not limited thereto. In some embodiments, the secondary storage component(s) 106 are used to store information such as program codes executable by the processing unit(s) 102, recorded waveforms for rendering by the signal generator 112, or signal flows or programs used to generate synthesized audio.

[0031] The one or more user interface component(s) 108 include input component(s) and output component(s). Input component(s) include one or more devices capable of providing input. Examples of input component(s) include, without limitation, a touch-sensitive surface (e.g., a touchpad), a microphone, a touch-sensitive screen, buttons, knobs, dials, a keyboard, a pointing device a mouse, a stylus), RFID tag readers, cameras, proximity sensors and/or

the like. Output component(s) include one or more devices of providing output. Examples of output component(s) include, without limitation, a display device, haptic devices, and/or the like. Examples of display component s) include, without limitation, LCD displays, LED displays, OLED displays, AMOLED displays, touch-sensitive displays, transparent displays, projection systems, and/or the like. Additionally, input component(s) and/or output component(s) can include devices capable of both receiving input and providing output, such as a touch-sensitive display, and/or the like.

[0032] The output section 116 includes, without limitation, amplifier 120 and speaker 122. The amplifier 120 amplifies one or more low-power audio signals received from the signal generator 112 according to a gain to increase a volume of the audio signals to a level sufficient to drive a speaker 122 or headphones. Types of audio amplifiers include, without limitation, Class A, Class B, Class AB, Class D, Class G, Class DG, and Class H. The type of amplifier used is dependent on the requirements of the application, such as power consumption, linearity, and efficiency. Speaker 122 can be a single speaker or can be a collection of speakers behind a frequency-splitting component such as a crossover. For example, a typical living room speaker can include a subwoofer, mid-range speaker, and tweeter behind a passive crossover. The subwoofer, mid-range speaker, and tweeter handle low, mid-range, and high- frequency portions of the audio signal, respectively. The amplifier 120 can be a single amplifier or can be a collection of amplifiers behind a frequency-splitting component such as a passive or active crossover. The various embodiments, amplifier 120 can be a single channel, mono, amplifier or a two channel, stereo, amplifier.

[0033] Each of the one or more batteries 126 stores electrical energy that is used to provide power to audio device 100. Each of the one or more batteries 126 can be any type of battery including, without limitation, an alkaline battery, a lithium-ion battery, (LiOn), a nickel-metal hydride (NiMH) battery, a nickel-cadmium (NiCd) battery, a lead acid battery, and the like. However, the present invention is not limited thereto. The audio device 100 can also be a mains-powered device.

[0034] FIG. 2 illustrates an audio signal flow diagram of the audio signal flow portion of audio device 100, according to one or more aspects of the various embodiments. The signal flow diagram shows, without limitation, the flow of audio signals and other information between signal generator 112, amplifier 120, speaker 122, slow-acting limiter 114, and a power measurement module 202. Generation of audio signals begins with signal generator 112. The signal generator 112 outputs the generated audio signal(s) to amplifier 120. The audio signal(s) output by the signal generator 112 can be determined based on inputs received from the user. For example, the user may select one or more songs from a media content service to play on the audio device 100. In another example, the user may bring an RFID tag in proximity to the RFID tag reader, which reads the data encoded in the tag and initiates the sequence of audio synthesis steps resulting in audio output from signal generator 112. The audio signals output by the signal generator 112 can also be output in response to inputs received from sensors. For example, a chime can play in response to a user opening a car door or a door to a merchant store.

[0035] Amplifier 120 receives the audio signal generated by signal generator 112. Amplifier 120 then amplifies the audio signal according to a gain 204 provided by slow-acting limiter 114 before outputting the amplified audio signal to speaker 122. Speaker 122 receives the amplified audio signal from amplifier 120 and then outputs the amplified audio signal as sound. In some instances, the amplification applied by gain 204 can be less than unity applying a negative dB value, resulting in an amplification is actually attenuation.

[0036] Power measurement module 202 measures the power level of the amplified audio signal and provides the measured power level to slow-acting limiter 114. In some embodiments, the measured power level is an instantaneous power of the amplified audio signal or the average power of the audio signal over a measurement period, such as an RMS power. Power measurement module 202 can use any technically feasible technique to determine the power level of the amplified audio signal, such as by measuring a voltage of the amplified audio signal and computing the power based on the measured or estimated voltage and either the average or frequency dependent impedance of speaker 122 and the like. The power can alternately be estimated from the output signal of the signal generator 112 and the system gains, rather than the output signal of the amplifier 120. Although not shown, power measurement module 202 can alternatively determine the power level based on an amount of power or current drawn from the one or more batteries 126 by output section 116.

[0037] The slow-acting limiter 114 controls the gain 204 of the amplifier 120 to help ensure that the audio device 100 meets or exceeds a battery run time goal. The power measurement module 202 periodically samples the power being consumed by the audio device 100 and provides sampled power consumption information to the slow-acting limiter 114. The slow-acting limiter 114 adjusts the gain 204 input to the amplifier 120 based on the power consumption information received from the power measurement module 202. In some embodiments, gain 204 can be implemented in or after signal generator 112, instead of in amplifier 120. When the power consumption is above the target power consumption level, excess power consumption is occurring. When the power consumption of the audio device 100 is above the target power consumption level, the slow-acting limiter 114 slowly ramps down the gain 204. When the power consumption drops below the target power consumption level, the slow-acting limiter 114 computes a gain profile for gain 204 to compensate for the excess energy consumed while the power consumption was above the target power consumption level. The slow-acting limiter 114 controls the gain 204 according to the gain profile until the actual energy consumption of the audio device 100 equals the target energy consumption. The slow-acting limiter 114 is further described in FIGs. 3-12.

[0038] FIG. 3 illustrates the effects of limiting an audio signal 310 using various techniques. The upper part of FIG. 3 shows a power level of an audio signal 310 that is not processed by a limiter. As shown beginning at time 312, audio signal 310 includes a first sound at a first power level. At time 314, the power level of audio signal 310 increases to a higher second power level. For example, the higher second power level could be caused by mixing the first sound with an additional sound that increases the overall power level, an increase in the power level of the first sound, or a change to a second sound with a higher power level. The audio signal 310 continues at the higher second power level until time 318, when the power level of audio signal 310 returns to the first power level. In cases where the first power level corresponds to a target power level for audio signals, such as due to a power budget for output section 116 when outputting audio signals, audio signal 310 should be limited so that the higher second power level does not unduly drain the one or more batteries 126 resulting in a shortened playback time relative to a target playback time.

[0039] Audio signal 330 illustrates how audio signal 310 is adjusted by a conventional limiter and further illustrates the undesirable audio artifacts that are introduced by the conventional limiter. Starting at time 312, the power level of audio signal 330 is at a first power level that is at or below the target power level and does not need to be limited by the convention limiter. However, at time 314 when the power level of audio signal 330 increases above the target power level, the conventional limiter acts to reduce the power level of audio signal 330 back to the target power level. From time 314 to time 316, the conventional limiter takes effect, and can cause a "pump" 332 that results in an undesirable audible distortion in audio signal 330. Similarly, when the second sound stops at time 318, the conventional limiter can cause an undershoot 334 at time 318 and an overshoot 336 at time 320 that results in another undesirable audible distortion in audio signal 330. The second sound finishes playing from time 326 to 328, and the conventional limiter has no effect. Between time 314 and 318, while the additional sound is playing, the amplitude of the first sound is attenuated relative to its level before time 314 but has a higher power than the input power in line with the characteristics of a conventional limiter. This will give the undesirable impression to listeners that the additional sound led to the momentary (from 314 to 318) suppression of the original sound, which is an undesirable listener experience.

[0040] Audio signal 350 illustrates how audio signal 310 is adjusted by the slow-acting limiter 114. Starting at time 312, the power level of audio signal 350 is at a first power level that is at or below the target power level and does not need to be limited by the slow-acting limiter 114. However, at time 314 when the power level of the audio signal 350 increases above the target power level, the slow-acting limiter 114 detects this and begins to slowly and imperceptibly ramp down the gain 204 of amplifier 120 so as to slowly reduce the power level of audio signal 350. While the slow-acting limiter 114 is ramping down the gain 204, the slow-acting limiter 114 also accumulates the amount of power above the target power level that is consumed by the audio signal 350 while the power level of the audio signal 350 is above the target power level. At time 318, when the additional components of audio signal 310 end, the power level of audio signal 350 drops below the target power level. The slow-acting limiter 114 detects that the power level of audio signal 350 has dropped below the target power level and responds by computing a gain profile for gain 204 to keep the power level of audio signal 350 low enough to compensate for the accumulated amount of power above the target power level that is consumed by audio signal 350 between time 314 and time 318. The gain profile for gain 204 includes a continued ramp down period between time 318 and time 322, a recovery period between time 322 and time 324 when gain 204 is kept constant, and a ramp-up period between time 324 and time 326 where the gain 204 is returned to the same level as before time 314.

[0041] FIG. 4 illustrates the depletion characteristics of various battery technologies. An ideal battery will maintain a constant voltage until the point of depletion. Different battery technologies come closer to the ideal. For example, alkaline batteries lose voltage over time and are considered depleted at point 406 when the voltage of the battery reaches seventy-five percent of the original voltage. Rechargeable and lithium batteries maintain a more constant voltage during discharge 404. In some embodiments, the battery level is monitored, and the pre-limiter gain is lowered progressively in order to extend battery life. Lowering the pre- limiter gain can be done in a gradual way, such that the audio device gets quieter and quieter to where it may only be playing one-quarter the original volume level (i.e. -12 dB). In some embodiments, the pre-limiter gain is lowered to a point where the power to the processor and the power to the speaker are approximately equal, but not to the point where the power to the speaker is ten percent of the total power drain of the system. The pre-limiter gain is the gain at the input of the slow-acting limiter 114 and can be attenuated independently of the gain 204 output from the slow-acting limiter 114. However, the reduction in gain by the slow-acting limiter 114 is relative to the gain set by the pre-limiter gain.

[0042] FIG. 5 illustrates the accumulated energy consumption in response to the audio signal 310 without the use of a limiter. The upper part of FIG. 3 showing audio signal 310 is repeated in FIG. 5, but the description of audio signal 310 is not repeated here. Illustration 502 shows the resultant accumulated energy consumption due to audio signal 310. From time 312 to time 314 when the power level of audio signal 310 is at the target power level, the actual energy consumption 504 of audio signal 310 and the target energy consumption 506 of audio signal 310 are accumulating at the same rate. At time 314 when the power level of audio signal 310 goes above the target power level and excess battery drain begins to occur, the actual energy consumption 504 and target energy consumption 506 begin to diverge, with the actual energy consumption 504 accumulating at a faster rate than the target energy consumption 506. At time 318 when the power level of the audio signal 310 returns to the target power level, the actual energy consumption 504 and the target energy consumption 506 begin accumulating at the same rate. However, without limiting the power level of the audio signal 310 between time 314 and time 318, the actual energy consumption 504 is greater than the target energy consumption 506, which results in a reduced battery lifetime for the one or more batteries 126.

[0043] FIG. 6 illustrates the accumulated energy consumption in response to the audio signal 310 of FIG. 3 where a conventional limiter is used. The portion of FIG. 3 showing audio signal 330 is repeated in FIG. 6, but the description of audio signal 330 is not repeated here. Illustration 602 shows the resultant accumulated energy consumption due to audio signal 330. From time 312 to time 314, when the power level of audio signal 330 is at the target power level, the actual energy consumption 604 of audio signal 330 and the target energy consumption 606 of audio signal 310 are accumulating at the same rate. The second sound starts playing at time 314 and the power level of audio signal 330 goes above the target power consumption level. The conventional limiter acts to compensate for this higher power level by applying a signal voltage dependent gain thereby limiting the voltage peaks in the audio signal to an upper maximum. That is, the conventional limiter applies the typical input voltage to output voltage compressor curve that results in limiting the peak output voltage, but when doing so, it creates an output signal with higher power than the input signal. Therefore, actual power consumption curve 604 begins to rise above the target power consumption level 606 at time 314 and continues to rise above level 606 until time 318 when the power level of audio signal 330 returns to the target power level. This also creates an overshoot 618 followed by an undershoot 620 between time 314 and time 316. During the period from time 314 to time 316, the power level of audio signal 330 initially goes above the target power level and excess battery drain occurs, but immediately thereafter the power level of audio signal 330 goes below the target power level and the excess battery drain is somewhat compensated for. As a result, the actual energy consumption 604 and target energy consumption 606 initially diverge 622, with the actual energy consumption 604 accumulating at a quicker rate than the target energy consumption 606, but then reconverging with the actual energy consumption 604 accumulating at a slower rate than the target energy consumption 606. During the time period from 316 to 318, when the output signal of the conventional limiter is at a higher power than the input signal, the actual energy consumption 604 and target energy consumption 606 diverge. When the second sound stops playing and the power level of the input audio signal returns to the target power level at time 318, the conventional limiter releases, resulting in an undershoot 624 followed by an overshoot 626 in audio signal 330. During the period from time 318 to time 320, the power level of audio signal 330 initially goes below 628 the target power level and then the power level of audio signal 330 goes above the target power level. As a result, the actual energy consumption 604 and target energy consumption 606 initially converge, with the actual energy consumption 604 accumulating at a slower rate than the target energy consumption 606, but then re-diverge somewhat with the actual energy consumption 604 accumulating at a quicker rate than the target energy consumption 606. Although the conventional limiter is able to limit the peak voltage output, it results in excess energy consumption relative to the target energy consumption during most time periods, and it also introduces the undesirable audio distortions between time 314 and time 316 and between time 318 and time 320.

[0044] FIG. 7 illustrates the accumulated energy consumption in response to the audio signal 310 where a slow-acting limiter 114 is used, according to one or more aspects of the various embodiments. The portion of FIG. 3 showing audio signal 350 is repeated in FIG. 7 and is further annotated as is described below, but the description of audio signal 350 is not repeated here. The excess power consumption caused by excess battery drain resulting from the second sound playing occurs during the overage period 722 which extends from time 314 to time 318. During the overage period 722, the excess power consumption is accumulated by the slow-acting limiter 114 and corresponds to the shaded area 712. The accumulation ends at time 318 when the slow-acting limiter 114 determines that the power level of audio signal 350 goes below the target power consumption level. At time 318, the slow-acting limiter 114 determines the gain profile to compensate for the accumulated excess power consumption during overage period 722. The amount of excess power consumption that the slow-acting limiter 114 recovers during recovery period 724 is shown as shaded area 714. The gain profile is determined so that a size of the shaded area 712 is made equal to a size of the shaded area 714.

[0045] Illustration 730 shows the relationship between an actual energy consumption 704 and a target energy consumption 706 for the audio signal 350. From time 312 to time 314 when the power level of audio signal 350 is at the target power level, the actual energy consumption 704 of audio signal 350 and the target energy consumption 706 of audio signal 350 are accumulating at the same rate. At time 314, when the power level of audio signal 350 goes above the target power level and excess battery drain begins to occur, the actual energy consumption 704 and target energy consumption 706 begin to diverge, with the actual energy consumption 704 accumulating at a faster rate than the target energy consumption 706. As the slow-acting limiter 114 begins to take effect and ramp down the gain of audio signal 350 between time 314 and time 318, the accumulation rate is reduced 750 as the excess battery drain is reduced. At time 318, as the second sound stops and the first sound continues playing at a reduced level, the battery drain drops further, the power level of audio signal 350 drops below the target power level, and the actual energy consumption 704 starts to converge 752 with the target energy consumption 706. From time 322 to time 324, as the power level of the audio signal 350 is held low and the battery drain is reduced, the actual energy consumption 704 accumulation rate is constant 754 and recovery continues with the actual energy consumption 704 continuing to converge with the target energy consumption 706. From time 324 to time 326, the first sound continues playing and the gain 120 of audio signal 350 is slowly ramped up as recovery is nearing completion. The actual energy consumption 704 continues to converge 756 with the target energy consumption 706 but at a rate slower than the previous period. At time 326, the actual energy consumption 704 and the target energy consumption 706 converge due to the operation of the slow-acting limiter 114. the first sound is again playing at the normal, nominal level, and the power level of audio signal 350 is at the target power level. In contrast to the conventional limiter of FIG. 6, the power and energy profiles of FIG. 7 show that the slow-acting limiter 114 is able to manage the energy consumption at the target level over this duration from 312 to 328 without introducing undesirable audio distortions.

[0046] FIG. 8 illustrates another gain profile of the slow-acting limiter 114 for the audio signal 310, according to one or more aspects of the various embodiments. From time 312 to time 314, the gain remains constant, with a gain of one, having no effect on the audio signal. The second sound starts playing at time 314. The gain remains at one from time 314 to time 308 during an attack delay 822 period, representing a zero dB reduction 850 in the amplitude of the audio signal. In some embodiments, the attack delay 822 period can have zero length. In practice, without using a look-ahead delay and an estimate of the power based on the input signal 310, the attack delay cannot be exactly zero because of the delays introduced by the power measurement 202 module sampling the power consumption and the slow-acting limiter 114 making the determination that the actual power consumption is exceeding the target power consumption level. In some embodiments, the attack delay 822 period can extend until after the second sound has finished playing, depending upon how long the second sound lasts. During the attack period 824 from time 308 to time 322, the gain is slowly ramped down from zero dB (gain of 1) to a predetermined maximum dB reduction 852 level. For some embodiments, the max dB reduction is set between -1 dB and -6 dB, inclusive, such as -3 dB (gain of .707), representing a halving of the power consumption. A change of 1 dB is generally accepted as the smallest difference in level that can be heard by most listeners listening to speech or music in an instantaneous A-B comparison listening test. In some embodiments, the battery level is monitored, and the pre-limiter gain is lowered progressively in order to extend battery life. The pre-limiter gain can be adjusted independently of the slow-acting limiter but the maximum dB reduction 852 is specified and operates relative to the pre-limiter gain. By making a -3 dB adjustment slowly, the changes in the audio signal are not detected by the typical listener. In some embodiments, the slope of the slow ramp down is determined based on the difference between the actual power consumption and target power consumption level when the actual power consumption is first determined to exceed the target power consumption at time 314. In some embodiments, the slope of the slow ramp down is a predetermined number of dB per second. During the recovery period 826, from time 322 to time 324, the gain is held constant at the level at which the slow ramp down ended. During the release period 828, from time 324 to time 326, the gain is ramped up from the value of at the end of the recovery period 826 back to one (i.e. zero dB reduction 850). From time 326 to time 328, the gain remains at one. In some embodiments, the recovery period 826 can last zero seconds. In some embodiments, the recovery period 826 is longer than the attack period 824 or the release period 828. The attack period 824 and the release period 828 need not need to be of the same length. However, in some embodiments, both should be greater than six seconds in length for the audible effects of the slow-acting limiter 114 to remain undetectable, unobtrusive, or unobjectionable by the typical listener.

[0047] FIG. 9 illustrates another audio signal and the accumulated energy consumption when a limiter is not applied to the audio signal. The upper part of FIG. 9 shows a power level of another audio signal 910 that is not processed by a limiter. As shown beginning at time 912, audio signal 910 includes a first sound at a first power level. At time 914, the power level of audio signal 910 increases to a higher second power level. For example, the higher second power level could be caused by mixing the first sound with an additional sound that increases the overall power level, an increase in the power level of the first sound, or a change to a second sound with a higher power level. At time 918 the power level of audio signal 910 returns to the first power level and continues at that level until time 920. At time 920 the power level of audio signal 910 again increases to the second power level and remains at the second power level until time 922 where the power level again returns to the first power level. In cases where the first power level corresponds to a target power level for audio signals, such as due to a power budget for output section 116 when outputting audio signals, audio signal 910 should be limited so that the higher second power level does not unduly drain the one or more batteries 126.

[0048] Illustration 930 shows the resultant accumulated energy consumption due to audio signal 910. From time 912 to time 914, when the power level of audio signal 910 is at the target power level, the actual energy consumption 904 of audio signal 910 and the target energy consumption 906 of audio signal 910 are accumulating at the same rate. At time 914, when the power level of audio signal 910 goes above the target power level, and excess battery drain begins to occur, the actual energy consumption 904 and target energy consumption 906 begin to diverge, with the actual energy consumption 904 accumulating at a quicker rate than the target energy consumption 906. At time 918 when the power level of the audio signal 910 returns to the target power level, the actual energy consumption 904 and the target energy consumption 906 again accumulate at the same rate. At time 920, when the power level of audio signal 910 again goes above the target power level, and excess battery drain again begins to occur, the actual energy consumption 904 and target energy consumption 906 again begin to diverge, with the actual energy consumption 904 again accumulating at a quicker rate than the target energy consumption 906. At time 922 when the power level of the audio signal 910 again returns to the target power level, the actual energy consumption 904 and the target energy consumption 906 again accumulate at the same rate. However, without limiting the power level of the audio signal 910 between time 914 and time 918, and again between time 920 and 922, the actual energy consumption 904 is greater than the target energy consumption 906, which results in a reduced battery lifetime for the one or more batteries 126.

[0049] FIG. 10 illustrates the accumulated energy consumption where a slow-acting limiter 114 is used in response to the another audio signal of FIG. 9, according to one or more aspects of the various embodiments. Audio signal 1010 illustrates how audio signal 910 is adjusted by the slow-acting limiter 114. Starting at time 912, the power level of audio signal 1010 is at a first power level that is at or below the target power level and does not need to be limited by the slow-acting limiter 114. However, at time 914 when the power level of the audio signal 1010 increases above the target power level, the slow-acting limiter 114 detects this and begins to slowly ramp down the gain 204 of amplifier 120 so as to slowly reduce the power level of audio signal 1010. While the slow-acting limiter 114 is ramping down the gain 204, the slow-acting limiter 114 also accumulates the amount of power above the target power level that is consumed by the audio signal 1010 while the power level of the audio signal 1010 is above the target power level. At time 918, when the additional components of audio signal 910 end, the power level of audio signal 1010 drops below the target power level. The slow- acting limiter 114 detects that the power level of audio signal 1010 has dropped below the target power level and responds by computing a gain profile for gain 204 to keep the power level of audio signal 1010 low enough to compensate for the accumulated amount of power above the target power level that is consumed by audio signal 1010 between time 914 and time 918. The gain profile for gain 204 includes a continued ramp down period between time 918 and time 922. At time 920, when the power level of the audio signal 1010 again increases above the target power level, the slow-acting limiter 114 again detects this and continues to slowly ramp down the gain 204 of amplifier 120 so as to continue to reduce the power level of audio signal 1010. At time 922, when the additional components of audio signal 910 again end, the power level of audio signal 1010 again drops below the target power level. The slow- acting limiter 114 again detects that the power level of audio signal 1010 has dropped below the target power level and responds by adjusting the gain profile for gain 204 to keep the power level of audio signal 1010 low enough to compensate for the accumulated amount of power above the target power level that is consumed by audio signal 1010 between time 914 and time 918 and again between time 920 and time 922. The adjusted gain profile for gain 204 includes a recovery period between time 922 and time 924 and a ramp up period between time 924 and time 926. In other examples, the gain ramp down may reach the predetermined target attenuation level at other times, during the second overage period 1016 between 920 and 922, or the gain ramp down may reach the predetermined target attenuation level after the overage period 1016 ends, between times 922 and 924.

[0050] The excess power consumption caused by excess battery drain resulting from the audio signal 1010 being above the target power level during a first overage period 1012 and a second overage period 1016 and is shown in shaded areas 1022 and 1024, respectively. The amount of energy consumption that must be compensated for by the slow-acting limiter 114 to account for the excess battery drain caused by the first overage period 1012 and the second overage period 1016 occurs during a first recovery period 1014 and a second recovery period 1018 and is shown in shaded areas 1028 and 1032, respectively. The slow-acting limiter 114 operates to make the total area of shaded areas 1022 and 1024 equal to the total area of shaded areas 1028 and 1032. At time 918, the power level drops below the target power level of typical operation 1020, triggering the slow-acting limiter 114 to determine the gain profile to compensate for the accumulated excess power consumption during the first overage period 1012. The slow-acting limiter 114 controls the gain of the amplifier 120 based on the gain profile from time 918 until time 920. At time 920, a third sound starts playing, and the gain profile is adjusted to allow the audio signal 1010 to continue to be ramped down. At time 922, the power level again drops below the target power level of typical operation 1020, triggering a second adjustment by the slow-acting limiter 114 of the gain profile to compensate for the accumulated excess power consumption of the shaded area 1022 that was not compensated for between time 918 and time 920 and the shaded area 1024. From time 922 to time 924 the slow-acting limiter follows the gain profile determined at time 922 and keeps the gain at a constant level. From time 924 to time 926 the follows the slow ramp up of the gain profile until the gain 204 is back at the level of typical operation.

[0051] Illustration 1050 shows the relationship between an actual energy consumption 1004 and a target energy consumption 1006 for the slow-acting limiter 114 based on the audio signal 910. The actual energy consumption 1004 and the target energy consumption 1006 accumulate at the same rate from time 912 when only the first sound is playing until time 914 when the second sound starts playing. The second sound starts playing at time 914 and the actual energy consumption 1004 initially increases in accumulation rate 1070 and then increases less rapidly as the slow-acting limiter 114 begins to ramp down the audio signal 910. At time 918, the actual energy consumption 1004 accumulation rate is lower than the target consumption rate as the slow ramp down of gain 204 continues. From time 920 to time 922 the actual energy consumption 1004 accumulation rate again increases 1074 as the third sound plays. This third sound could also be the second sound playing again. From time 922 to time 924 the actual energy consumption 1004 accumulation rate 1076 is constant as the gain 204 is held constant during the second recovery period 1018. From time 924 to time 926, the actual energy consumption 1004 accumulation rate decreases 1078 as the slow-acting limiter 114 completes the second recovery period 1018. The actual energy consumption 1004 and the target energy consumption 1006 converge at time 926 due to the effects of the slow-acting limiter 114.

[0052] A preliminary estimate of the slow acting limiter 114 gain profile can be computed even before the first overage period ends. If the excess power drain is above a threshold, then higher gain slopes (i.e. in dB/second) or higher overall attenuation level for the gain of slow acting limiter 114 (i.e. in dB) can be used in order to minimize the duration of the recovery period (i.e. so the recovery period is not greater than a predetermined duration such as 30 seconds. In an embodiment, there is a look up table of predetermined gain slopes and/or predetermined gains 204 as a function of either excess power or actual energy consumption relative to target energy consumption. In an embodiment, the slope of the gain of slow acting limiter 114 can change during an overage period, if the excess power consumption exceeds predetermined thresholds listed in a look up table. In an embodiment, there is a single threshold, or multiple thresholds that do not take the form of a look up table. In an embodiment, the power level in the first sound may decrease during the recovery period (or other period), resulting either in the recalculation of the gain profile, or a premature end of the recovery period, as the actual power consumption equals and then drops below the target power consumption. In this case, the gain ramp can maintain it predetermined profile to ramp elegantly back to 1 (0 dB), resulting in the actual power consumption being slightly lower than the target power consumption.

[0053] FIG. 11 illustrates another gain profile of the slow-acting limiter 114 for the audio signal 910, according to one or more aspects of the various embodiments. The gain remains constant from time 912 to time 914, with a gain of one representing a zero dB reduction 1150 in the audio signal. The second sound starts playing at time 914. The gain remains at one from time 914 to time 916 during an attack delay period 1122. In some embodiments, the attack delay period 1122 can be close to or substantially zero seconds. During an attack period 1124 from time 916 to time 922, the gain is slowly ramped down from zero dB (gain of 1) toward a maximum dB reduction 1152 level. The attack period 1124 consists of three consecutive ramp down periods. The first ramp down period 1130 and second ramp down period 1132 occur in response to the second sound playing the first time and are included as part of the initial gain profile to recover from the first occurrence of the second sound from time 914 to time 918. The third ramp down period 1134 is included as part of the adjusted gain profile that replaces the initial gain profile in response to the third sound playing beginning at time 920 and before the excess battery drain from the playing of the second sound is fully accounted for. As shown, the first ramp down 1130 and the second ramp down 1132 have a different slope than the third ramp down 1134 (i.e. initial rate 1140 vs a revised rate 1142). At time 918, as the second sound finishes playing, the slow-acting limiter 114 can also adjust the gain profile between the first ramp down 1130 and the second ramp down 1132. In the example of FIG.

11, that adjustment is omitted or alternatively the adjustment is a zero dB adjustment. During the recovery period 1126, from time 922 to time 924, the gain is held constant at the level at which the slow ramp down ended. During the release period 1128, from time 924 to time 926, the gain is ramped up from the value at the end of the recovery period 1126 back to one (zero dB reduction 1150). From time 926 to time 928, the gain remains at one. In some embodiments, the recovery period 1126 can last zero seconds. In some embodiments, the recovery period 1126 is longer than the attack period 1124 or the release period 1128. The attack period 1124 and the release period 1128 need not need to be of the same length.

However, in some embodiments, both should be greater than six seconds in length for the audible effects to remain undetectable, unobtrusive, or unobjectionable to a typical listener.

Process Overview

[0054] FIG. 12 is a flow diagram of method steps for managing the power consumption of an audio device 100 using a slow-acting limiter 114, according to various embodiments.

Although the method steps are described in conjunction with the systems and embodiments of FIGs 1-11, persons of ordinary skill in the art will understand that any system configured to perform the method steps, in any order, is within the scope of the present disclosure.

[0055] As shown in FIG. 12, the method begins at step 1202, where the power consumption of the output section 116 of the audio device 100 is monitored to detect when actual power consumption exceeds a target power consumption level. The target power consumption level can be predetermined, based on the battery life goal of the audio device 100. The actual power consumption can be determined by the power measurement module 202 by monitoring the voltage across the speaker 122 or by monitoring the current drain from the one or more batteries 126, by any of the other aforementioned methods, or by any other method known to those of ordinary skill in the art.

[0056] At step 1204, the slow-acting limiter 114 receives a new power consumption measurement from the power measurement module 202 and performs a comparison of the actual power consumption to the target power consumption level. If the actual power consumption exceeds the target power consumption level, the method continues at step 1206 (1204 YES). An example of the overage in power consumption from the battery current drain resulting from a single second sound playing and increasing the power consumption above the target power consumption level is shown as overage period 722 of FIG. 7. An example of the overage in power consumption for a third sound or a repeated second sound playing and increasing the power consumption above the target power consumption level is shown as second overage period 1016 of FIG. 10. Otherwise, the method returns to step 1202 (1204 NO) and the monitoring of power consumption continues. The target power consumption level can be determined by dividing the energy capacity of the battery by the desired battery life.

[0057] At step 1206, the slow-acting limiter 114 applies an optional attack delay. In some embodiments, the attack delay will be as short as zero seconds (i.e., optional). In some embodiments, the attack delay can extend until after a second sound has finished playing. In practice, without using a look ahead delay, the attack delay can never be exactly zero because of the delays introduced by the power measurement module 202 sampling the power consumption and the slow-acting limiter 114 making the determination that the actual power consumption is exceeding the target power consumption level. In an embodiment using a look- ahead delay, the output of signal generator 112 can be delayed such than an analysis of the audio samples to be output can be performed before they are output. The analysis can determine an estimate of the actual power consumption that will result when those audio samples are output to amplifier 120, such that gain 204 can be applied at step 1208 after a zero second attack delay.

[0058] At step 1208, the slow-acting limiter 114 begins the slow ramp down of the audio signal. The downward ramp of the audio signal continues until the power consumption, as determined by the power measurement module 202, drops below the target power consumption level. In some embodiments, for the effect of the slow-acting limiter 114 to be inaudible or unobjectionable, the downward ramp should have a duration of around six seconds. In some embodiments, the slope of the slow ramp down is determined based on the difference between the actual power consumption and target power consumption level when the actual power consumption is first determined to exceed the target power consumption at step 1204.

[0059] At step 1210, the slow-acting limiter 114 receives a new power consumption measurement from the power measurement module 202 and performs a comparison of the actual power consumption to the target power consumption level. If the actual power consumption reaches or drops below the target power consumption level, the method continues at step 1214 (1210 YES). Otherwise, the method continues at step 1212 (1214 NO).

[0060] At step 1212, the slow-acting limiter 114 accumulates the power consumption above the target power consumption level as the accumulated energy consumption. The slow- acting limiter 114 accumulates each new power consumption measurement from the power measurement module 202.

[0061] At step 1214, the slow-acting limiter 114 computes a gain profile to compensate for the excess power consumption. The gain profile includes an attack period, a recovery period, and a release period. The shape of the gain profile is dependent on the actual energy consumption that needs to be recovered. For example, the shape of the gain profile for a single second sound is shown in FIG. 8 and can have a different shape than the gain profile for a third sound or repeated second sound which is shown in FIG. 11. In particular, the gain profile of FIG. 11 has a prolonged attack period 1124 and a prolonged recovery period 1126 compared to the gain profile of FIG. 8, or it can have a higher maximum attenuation level during recovery period 1126, or a higher slope during all or portions of attack period 1124 or the release period 1128 than those values in the corresponding periods shown in FIG. 8.

[0062] At step 1216, the slow-acting limiter 114 controls the gain of the amplifier 120 based on the gain profile. The slow-acting limiter 114 controls the gain by applying the gain profile to the audio signal as the gain profile transitions through an optional attack delay period, attack period, recovery period, and release period. Once the gain profile has ended, control returns to step 1202, and monitoring of the power consumption continues.

[0063] In sum, techniques are disclosed that enable a slow-acting limiter to condition an audio signal to manage power consumption of an audio device. The techniques apply to battery-powered audio devices to meet battery life goals. The power consumption of the output section of the device is monitored to detect when actual power consumption exceeds target power consumption. The actual power consumption can be determined by monitoring the voltage across a speaker or by monitoring the current drain from the battery or other methods. Upon determining that the actual power consumption exceeds the target power consumption, an optional attack delay is applied before the slow acting limiter responds. At the end of the attack delay, the slow-acting limiter begins a slow ramp down of the signal gain. The power consumption of the output section of the device is monitored to detect when the actual power consumption drops below the target power consumption. Until the actual power consumption drops below the target power consumption, the excess power consumed above the target power consumption is accumulated. Upon the actual power consumption dropping below the target power consumption, the slow-acting limiter computes a gain profile based on the accumulated excess power consumption. The gain profile includes a ramp down period, recovery period, and ramp up period and is computed to recover the accumulated excess power consumption. The ramp up and ramp down in gain occur over a time period that is long enough as to be imperceptible or unobjectionable to the listener. The slow-acting limiter controls the gain of the audio device based on the gain profile. The gain profile can be revised based on the occurrence of additional periods where the actual power consumption again exceeds the target power consumption or when the actual power consumption rate relative to the target rate is greater than a threhold before the initial accumulated excess power consumption is recovered.

[0064] At least one technical advantage of the disclosed techniques relative to the prior art is that, with the disclosed techniques, audio output is managed based on a target life for a battery in an audio device. The disclosed techniques additionally allow the life of the battery to be extended even when the audio device periodically outputs sounds that require the output section of the audio output device to consume an amount of power that exceeds a baseline allotted to the output section. In addition, the described techniques do not induce the typical audio artifacts that occur when using conventional audio limiters. The technical advantages provide one or more technological advancements over prior art approaches.

[0065] 1. In various embodiments, a computer-implemented method for managing power consumption of an audio device, the method comprising: detecting that a power consumption of the audio device is above a target power consumption level; in response to detecting that the power consumption of the audio device is above the target power consumption level: ramping down a gain of the audio device; accumulating an amount of the power consumption of the audio device that is above the target power consumption level to generate an accumulated excess power consumption of the audio device; computing a gain profile to compensate for the accumulated excess power consumption; and controlling the gain of the audio device based on the gain profile.

[0066] 2. The method of clause 1, wherein detecting that the power consumption of the audio device is above the target power consumption level comprises monitoring a portion of a current drain from one or more batteries attributed to powering an amplifier of the audio device.

[0067] 3. The method of clauses 1 or 2, wherein detecting that the power consumption of the audio device is above the target power consumption level comprises one of monitoring a voltage applied across a speaker of the audio device or monitoring the current consumption of the amplifier.

[0068] 4. The method of clauses 1-3, further comprising determining the target power consumption level based on a target life of one or more batteries.

[0069] 5. The method of clauses 1-4, further comprising delaying, after determining that the power consumption of the audio device is above the target power consumption level, before ramping down the gain of the audio device.

[0070] 6. The method of clauses 1-5, further comprising determining a rate of the ramping down based on a ratio of the power consumption to the target power consumption level.

[0071] 7. The method of clauses 1-6, wherein accumulating the amount of the power consumption of the audio device that is above the target power consumption level comprises: periodically receiving values indicating the power consumption; and accumulating the values of the power consumption.

[0072] 8. The method of clauses 1-7, wherein the gain profile includes a first period where the gain continues to be ramped down and a second period where the gain is ramped up.

[0073] 9. The method of clauses 1-8, wherein the gain profile further includes a third period between the first period and the second period where the gain is constant.

[0074] 10. The method of clauses 1-9, further comprising selecting a rate of the ramping down of the gain to reduce a likelihood that changes in the gain due to the ramping down of the gain are detected by a user.

[0075] 11. In various embodiments, one or more non-transitory computer-readable media storing instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of: detecting that a power consumption of an audio device is above a target power consumption level; in response to detecting that the power consumption of the audio device is above the target power consumption level: ramping down a gain of the audio device; accumulating an amount of the power consumption of the audio device that is above the target power consumption level to generate an accumulated excess power consumption of the audio device; computing a gain profile to compensate for the accumulated excess power consumption; and controlling the gain of the audio device based on the gain profile.

[0076] 12. The one or more non-transitory computer-readable media of clause 11, wherein the steps further comprise one of: detecting that the power consumption of the audio device is above the target power consumption level comprises monitoring a portion of a current drain from one or more batteries attributed to powering an amplifier of the audio device, detecting that the power consumption of the audio device is above the target power consumption level comprises monitoring a voltage applied across a speaker of the audio device, or determining the target power consumption level based on a target life of one or more batteries.

[0077] 13. The one or more non-transitory computer-readable media of clauses 11 or 12, wherein the steps further comprise delaying, after determining that the power consumption of the audio device is above the target power consumption level, before ramping down the gain of the audio device.

[0078] 14. The one or more non-transitory computer-readable media of clauses 11-13, wherein the gain profile includes a first period where the gain continues to be ramped down and a second period where the gain is ramped up.

[0079] 15. The one or more non-transitory computer-readable media of clauses 11-14, wherein the gain profile further includes a third period between the first period and the second period where the gain is constant.

[0080] 16. The one or more non-transitory computer-readable media of clauses 11-15, wherein the steps further comprise selecting a rate of the ramping down of the gain to reduce a likelihood that changes in the gain due to the ramping down of the gain are detected by a user.

[0081] 17. The one or more non-transitory computer-readable media of clauses 11-16, wherein the steps further comprise: detecting, while controlling the gain according to the gain profile, that the power consumption of the audio device is again above the target power consumption level, in response to detecting that the power consumption of the audio device is again above the target power consumption level: accumulating a second amount of the power consumption of the audio device that is above the target power consumption level to generate a second accumulated excess power consumption of the audio device; computing a second gain profile to compensate for a non-recovered portion of the accumulated excess power consumption and the second accumulated excess power consumption; and controlling the gain of the audio device based on the second gain profile.

[0082] 18. In various embodiments, a toy -based audio device comprises: a speaker; an amplifier coupled to the speaker; one or more memories storing instructions; and one or more processors that are coupled to the one or more memories and the amplifier that, when executing the instructions, perform the steps of: detecting that a power consumption of the audio device is above a target power consumption level; in response to detecting that the power consumption of the audio device is above the target power consumption level: ramping down a gain of the amplifier; accumulating an amount of the power consumption of the audio device that is above the target power consumption level to generate an accumulated excess power consumption of the audio device; computing a gain profile to compensate for the accumulated excess power consumption; and controlling the gain of the amplifier based on the gain profile.

[0083] 19. The toy -based audio device of clause 18, further comprising a power measurement module that determines the power consumption of the audio device by one of: monitoring a portion of a current drain from one or more batteries attributed to powering the amplifier of the audio device, or monitoring a voltage applied across the speaker.

[0084] 20. The toy -based audio device of clauses 18 or 19, further comprising selecting a rate of the ramping down of the gain to reduce a likelihood that changes in the gain due to the ramping down of the gain are detected by a user.

[0085] Any and all combinations of any of the claim elements recited in any of the claims and/or any elements described in this application, in any fashion, fall within the contemplated scope of the present invention and protection.

[0086] The descriptions of the various embodiments have been presented for purposes of illustration but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

[0087] Aspects of the present embodiments may be embodied as a system, method or computer program product. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “module,” a “system,” or a “computer.” In addition, any hardware and/or software technique, process, function, component, engine, module, or system described in the present disclosure may be implemented as a circuit or set of circuits. Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.

[0088] Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0089] Aspects of the present disclosure are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine. The instructions, when executed via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions/acts specified in the flowchart and/or block diagram block or blocks. Such processors may be, without limitation, general purpose processors, special-purpose processors, applicationspecific processors, or field-programmable gate arrays.

[0090] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0091] While the preceding is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

WHAT IS CLAIMED IS:

1. A computer-implemented method for managing power consumption of an audio device, the method comprising: detecting that a power consumption of the audio device is above a target power consumption level; in response to detecting that the power consumption of the audio device is above the target power consumption level: ramping down a gain of the audio device; accumulating an amount of the power consumption of the audio device that is above the target power consumption level to generate an accumulated excess power consumption of the audio device; computing a gain profile to compensate for the accumulated excess power consumption; and controlling the gain of the audio device based on the gain profile.

2. The computer-implemented method of claim 1, wherein detecting that the power consumption of the audio device is above the target power consumption level comprises monitoring a portion of a current drain from one or more batteries attributed to powering an amplifier of the audio device.

3. The computer-implemented method of claim 1, wherein detecting that the power consumption of the audio device is above the target power consumption level comprises one of monitoring a voltage applied across a speaker of the audio device or monitoring the current consumption of the amplifier.

4. The computer-implemented method of claim 1, further comprising determining the target power consumption level based on a target life of one or more batteries.

5. The computer-implemented method of claim 1, further comprising delaying, after determining that the power consumption of the audio device is above the target power consumption level, before ramping down the gain of the audio device.

6. The computer-implemented method of claim 1, further comprising determining a rate of the ramping down based on a ratio of the power consumption to the target power consumption level.

7. The computer-implemented method of claim 1, wherein accumulating the amount of the power consumption of the audio device that is above the target power consumption level comprises: periodically receiving values indicating the power consumption; and accumulating the values of the power consumption.

8. The computer-implemented method of claim 1, wherein the gain profile includes a first period where the gain continues to be ramped down and a second period where the gain is ramped up.

9. The computer-implemented method of claim 8, wherein the gain profile further includes a third period between the first period and the second period where the gain is constant.

10. The computer-implemented method of claim 1, further comprising selecting a rate of the ramping down of the gain to reduce a likelihood that changes in the gain due to the ramping down of the gain are detected by a user.

11. One or more non-transitory computer-readable media storing instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of: detecting that a power consumption of an audio device is above a target power consumption level; in response to detecting that the power consumption of the audio device is above the target power consumption level: ramping down a gain of the audio device; accumulating an amount of the power consumption of the audio device that is above the target power consumption level to generate an accumulated excess power consumption of the audio device; computing a gain profile to compensate for the accumulated excess power consumption; and controlling the gain of the audio device based on the gain profile.

12. The one or more non-transitory computer-readable media of claim 11, wherein the steps further comprise one of: detecting that the power consumption of the audio device is above the target power consumption level comprises monitoring a portion of a current drain from one or more batteries attributed to powering an amplifier of the audio device, detecting that the power consumption of the audio device is above the target power consumption level comprises monitoring a voltage applied across a speaker of the audio device, or determining the target power consumption level based on a target life of one or more batteries.

13. The one or more non-transitory computer-readable media of claim 11, wherein the steps further comprise delaying, after determining that the power consumption of the audio device is above the target power consumption level, before ramping down the gain of the audio device.

14. The one or more non-transitory computer-readable media of claim 11, wherein the gain profile includes a first period where the gain continues to be ramped down and a second period where the gain is ramped up.

15. The one or more non-transitory computer-readable media of claim 14, wherein the gain profile further includes a third period between the first period and the second period where the gain is constant.

16. The one or more non-transitory computer-readable media of claim 11, wherein the steps further comprise selecting a rate of the ramping down of the gain to reduce a likelihood that changes in the gain due to the ramping down of the gain are detected by a user.

17. The one or more non-transitory computer-readable media of claim 11, wherein the steps further comprise: detecting, while controlling the gain according to the gain profile, that the power consumption of the audio device is again above the target power consumption level, in response to detecting that the power consumption of the audio device is again above the target power consumption level: accumulating a second amount of the power consumption of the audio device that is above the target power consumption level to generate a second accumulated excess power consumption of the audio device; computing a second gain profile to compensate for a non-recovered portion of the accumulated excess power consumption and the second accumulated excess power consumption; and controlling the gain of the audio device based on the second gain profile.

18. A toy -based audio device comprising: a speaker; an amplifier coupled to the speaker; one or more memories storing instructions; and one or more processors that are coupled to the one or more memories and the amplifier that, when executing the instructions, perform the steps of: detecting that a power consumption of the audio device is above a target power consumption level; in response to detecting that the power consumption of the audio device is above the target power consumption level: ramping down a gain of the amplifier; accumulating an amount of the power consumption of the audio device that is above the target power consumption level to generate an accumulated excess power consumption of the audio device; computing a gain profile to compensate for the accumulated excess power consumption; and controlling the gain of the amplifier based on the gain profile.

19. The toy -based audio device of claim 18, further comprising a power measurement module that determines the power consumption of the audio device by one of: monitoring a portion of a current drain from one or more batteries attributed to powering the amplifier of the audio device, or monitoring a voltage applied across the speaker.

20. The toy -based audio device of claim 18, further comprising selecting a rate of the ramping down of the gain to reduce a likelihood that changes in the gain due to the ramping down of the gain are detected by a user.