Smart volume controller and method thereof

Abstract

To provide a smart volume controller that achieves superior audio fidelity or power efficiency.SOLUTION: A controller configured to control the sound generation module includes a volume control configured to determine a demodulation amplitude and a modulation amplitude corresponding to a target volume. The sound generation module includes a drive circuit and an air pulse generation device. The drive circuit generates a demodulated drive signal according to the demodulated amplitude and generates a modulated drive signal according to the modulated amplitude to drive the air pulse generation device. The air pulse generation device generates sound by generating a plurality of air pulses at an ultrasonic pulse rate.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present application relates to a smart volume controller and a control method thereof, and more particularly to a smart volume controller and a control method thereof that achieves excellent audio fidelity or power efficiency. [Background technology]

[0002] Volume control mechanisms in conventional audio systems often compromise sound quality and operational efficiency. A major challenge lies in digital volume reduction, a widely adopted technique that inherently degrades the signal-to-quantization noise ratio (SQNR). This occurs through truncation of least significant bits (LSBs), resulting in a reduced effective bit depth and an increased noise floor for attenuated signals. Thus, achieving a comfortable listening level often comes with a loss of audio fidelity, where essential audio details are masked by quantization noise.

[0003] Furthermore, conventional transducers inherently lack direct sensitivity control. This lack necessitates that volume adjustment be managed by modifying the driving electrical signal from a digital-to-analog converter (DAC), resulting in increased power consumption at higher volumes. This forces a critical trade-off between power efficiency and sound quality: operating the DAC at full resolution for the sake of fidelity consumes more power, or sacrificing resolution for power savings results in higher noise. Post-DAC alternatives, such as voltage dividers and acoustic cavity designs, are similarly inadequate, often introducing noise, linearity issues, or mechanical complexity without providing the high-resolution control required for modern high-fidelity systems. These persistent limitations highlight the urgent need for solutions that overcome SQNR degradation and optimize power usage without compromise. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 11,943,585 [Patent Document 2] U.S. Patent No. 12,261,567 [Patent Document 3] U.S. Patent No. 12,107,546 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, the main objective of the present application is to provide a smart volume controller and method thereof that achieves excellent audio fidelity or power efficiency, and improves upon the disadvantages of the prior art. [Means for solving the problem]

[0006] One embodiment of the present application provides a controller configured to control a sound generation module, the controller including a volume control unit configured to determine a demodulation amplitude and a modulation amplitude corresponding to a target volume. The sound generation module includes a drive circuit and an air pulse generating device. The drive circuit generates a demodulation drive signal according to the demodulation amplitude and a modulation drive signal according to the modulation amplitude to drive the air pulse generating device. The air pulse generating device generates sound by generating a plurality of air pulses at an ultrasonic pulse rate.

[0007] One embodiment of the present application provides a controller configured to control a sound generation module, the controller including a volume control unit, the sound generation module including an air pulse generating device, the air pulse generating device generating sound by generating a plurality of air pulses at an ultrasonic pulse rate, the volume control unit adjusting a parameter such that an operating frequency of the air pulse generating device is adjusted, and the volume of the sound generated by the air pulse generating device is adjusted by adjusting the operating frequency.

[0008] One embodiment of the present application provides a volume determination method applied to a volume control unit in a controller for controlling a sound generation module. The volume determination method includes determining a demodulation amplitude and a modulation amplitude corresponding to a target volume. The sound generation module includes a drive circuit and an air pulse generating device. The drive circuit generates a demodulation drive signal according to the demodulation amplitude and a modulation drive signal according to the modulation amplitude to drive the air pulse generating device. The air pulse generating device generates sound by generating a plurality of air pulses at an ultrasonic pulse rate.

[0009] An embodiment of the present application provides a volume adjustment method configured to adjust a volume of a sound generation module, the volume adjustment method including adjusting an operating frequency of an air pulse generating device corresponding to an ultrasonic pulse rate, the sound generation module including an air pulse generating device, the air pulse generating device generating sound by generating a plurality of air pulses at the ultrasonic pulse rate. [Brief explanation of the drawings]

[0010] These and other objects of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

[0011] [Figure 1] 1 shows an air pulse generating (APG) device. [Figure 2] 2 illustrates demodulated and modulated drive signal waveforms for the APG device of FIG. 1. [Figure 3] The characteristic curves of the conductance of the virtual valve versus the displacement difference and the AM demodulator for AM demodulation are shown. [Figure 4] The air flow I(t), the air pressure wave P(t) and the conductance G(t) of the virtual valve are shown. [Figure 5] 1 shows a schematic diagram of a sound generation system according to an embodiment of the present application; [Figure 6] 1 shows four sets of parameter curves according to an embodiment of the present application. [Figure 7]2 shows a curve of displacement gain versus Fr / Fv ratio for the APG device of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] The contents of U.S. Patent Nos. 11,943,585, 12,261,567 and 12,107,546 are incorporated herein by reference.

[0013] By utilizing the features of an air pulse generating (APG) device and its corresponding driver circuit, it is possible to integrate sensitivity adjustment into the volume control of a sound generating system to achieve superior audio fidelity.

[0014] U.S. Patent No. 11,943,585 filed by the applicant discloses an air pulse generating (APG) device 10 shown in FIG. 1. The APG device 10 includes a pair of flaps, including flaps 101 and 103. The APG device 10 also includes an actuator 101A disposed on the flap 101 and an actuator 103A disposed on the flap 103. The actuators 101A / 103A are driven by demodulated drive signals S101 / S103 and modulated drive signals SM to generate multiple air pulses at an ultrasonic pulse rate. The actuators 101A / 103A include an upper electrode and a lower electrode. These two electrodes receive the demodulated drive signal and the modulated drive signal. In the embodiment shown in FIG. 1, the upper electrode receives the demodulated drive signal S101 / S103, and the lower electrode receives the modulated drive signal SM, but this is not limiting.

[0015] The modulated drive signal SM causes the flap pair to move in common mode. The demodulated drive signals S101 and S103 cause the flap pair to move in differential mode. z,101 and U z,103 represent the displacements (Z / vertical direction) of the flaps 101 and 103, respectively. Then, the common mode motion is z,101 + U z,103 ) / 2, and differential mode motion refers to the component of motion of the flap pair that is |U z,101 -Uz,103 It refers to the movement component of the flap pair that is | / 2.

[0016] A slit 112 is formed between the flaps 101 and 103. The pair of flaps undergoes differential mode motion (sometimes abbreviated as differential motion), and ΔU z = |U z,101 -U z,103 When | is greater than the thickness of the flap, an opening (also designated 112) is formed. In one respect, the differential movement of flaps 101 and 103 forms a virtual valve, also designated 112. ΔU z If ΔU is small (less than the flap thickness) and / or the acoustic impedance / resistance is large and the airflow through the virtual valve 112 is negligible, the virtual valve 112 can be viewed as a slit 112 shown in FIG. z If the acoustic impedance / resistance is large (greater than the flap thickness) and / or the acoustic impedance / resistance is small and there is significant airflow through the virtual valve 112, the virtual valve 112 can be considered as an opening 112 as shown in FIG. 1(b).

[0017] The waveforms of the demodulation drive signals S101 and S103 and the modulation drive signal SM are shown in FIG. 2. The waveform of the modulation drive signal SM can be viewed as a (generalized) double sideband with suppressed carrier (DSB-SC), and a definition of "generalized DSB-SC" is provided in U.S. Patent No. 11,943,585 filed by the applicant. For the sake of brevity, this definition is not mentioned herein. The waveforms of the demodulation drive signals S101 / S103 can be viewed as, but are not limited to, square / rectangular waves (similar to clock signals). Note that the phase relationship between the modulation drive signal and the demodulation drive signal can be changed as appropriate and is not limited to the embodiment shown in FIG. 2.

[0018] The demodulation drive signals S101 and S103 may or may not be biased to the same level. When the demodulation drive signals S101 and S103 are biased to the same level, the flap pair undergoes symmetric differential motion without initial deflection. In this case, the demodulation drive signals S101 and S103 may also be represented as +SV and −SV, as shown in FIG. 2(a). In this application, the notation “SV” is used to generally refer to the demodulation drive signal, which may represent either S101 or S103. On the other hand, when the demodulation drive signals S101 and S103 are biased to different levels, the flap pair undergoes asymmetric differential motion with asymmetric initial deflection. Here, the mechanical initial deflection of the flap corresponds to the voltage bias in / out of the demodulation drive signals.

[0019] As an example, assuming that the flap pair performs symmetric differential motion without initial deflection as shown in Fig. 2(a), the demodulation frequency of the demodulated drive signals S101 / S103 can be half the modulation frequency of the modulated drive signal SM. As another example, assuming that the flap pair performs asymmetric differential motion with asymmetric initial deflection as shown in Fig. 2(b), the demodulation frequency of the demodulated drive signals S101 / S103 can be the same as the modulation frequency of the modulated drive signal SM.

[0020] In this application, the demodulation frequency of the demodulated drive signal is also referred to as the operating frequency of the APG device and is represented by F. The ultrasonic pulse rate is the modulation frequency of the modulated drive signal and corresponds to the operating frequency F.

[0021] In the embodiment of Fig. 2(a), the virtual valve 112 is closed corresponding to the period when the demodulated drive signals S101 and S103 are transitioning. In the embodiment of Fig. 2(b), the virtual valve 112 is closed when one demodulated drive signal is at a high level and the other is at a low level. For example, assuming that the flap 101 is initially deflected upward and the flap 103 is initially deflected downward in Fig. 2(b), the virtual valve 112 is closed when the signal S103 is at a high level and the signal S101 is at a low level.

[0022] As taught in 11,943,585, in terms of modulation, a modulating drive signal SM that provides common mode motion leads to the generation of amplitude modulated (AM) waves (pressure fluctuations). In terms of demodulation, a virtual valve 112 controlled by a demodulating drive signal SV acts as an acoustic diode for AM demodulation, which is detailed in Figures 3 and 4.

[0023] FIG. 3 shows the conductance G of the virtual valve 112. valve Displacement difference ΔU z 3(a) and an AM demodulator or envelope detector for AM demodulation (FIG. 3(b)). In FIG. 3(a), the characteristic curve is upwardly convex or concave, and in particular, ΔU z When is larger, the displacement difference ΔU z As increases, the valve conductance G valve increases faster. The characteristic curve of the virtual valve 112 resembles that of a diode. The virtual valve 112 can be used as an acoustic diode, for example, in the context of AM demodulation. AM demodulation is well known to those skilled in the art. An analogy between the demodulation operation performed by the APG device and a conventionally known AM demodulator is given below. In FIG. 3(b), "V I " may resemble an AM wave or AM pressure fluctuation, "diode D" may resemble a virtual valve 112, "capacitor C" and "resistor R L " represents the surrounding acoustic capacitance and acoustic resistance, which together form a low pass filter (LPF), and "Vo" may resemble / correspond to the sound perceived by the human ear.

[0024] In other words, common mode motion is "V I When generating an AM wave or AM pressure fluctuation as a sine wave, the virtual valve 112 acts as a diode "D" (as a rectifier) ​​to generate unipolar air pulses, and the surrounding embedded acoustic capacitance "C" and resistance "R" L " acts as an LPF to remove the ultrasonic components, leaving the audible portion (within the audible spectrum band) "Vo" to the human auditory system.

[0025] To see how a rectifier works, Figure 4 shows the air flow I(t) generated by an APG device, which can be expressed as (or in terms of) the product of the air pressure wave P(t) and the virtual valve conductance G(t), mathematically I(t) = P(t) G(t) (Equation 1), showing the effect of the rectifier (provided by the diode or virtual valve 112) in the AM demodulator or envelope detector.

[0026] It should be noted that the amplitude of the output airflow I(t) determines the volume of sound that the APG device can generate as a sound generating device. Meanwhile, according to the concept of FIG. 4 and Equation 1, the amplitude of the output airflow I(t) is determined by both the amplitude of the AM pressure wave P(t) (assuming that P(t) is amplitude modulated) and the amplitude of the conductance G(t). The amplitude of the AM pressure wave P(t) is affected by the amplitude of the modulated drive signal, denoted as SMamp. The amplitude of the conductance G(t) is determined by the displacement difference ΔU z is affected by the displacement difference ΔU z is affected at least by the amplitude of the demodulated drive signal, denoted as SVamp.

[0027] In conclusion, the volume of the APG device as a sound generating device can be adjusted by both SVamp (the amplitude of the demodulated drive signal SV) and SMamp (the amplitude of the modulated drive signal SM), where SVamp can be regarded as an adjustable parameter for sensitivity adjustment.

[0028] 5 shows a schematic diagram of a sound-generating system 2 according to one embodiment of the present application. The sound-generating system 2 includes a controller 20 and a sound-generating module 22. The sound-generating module 22 includes a driver circuit 12 and an APG device 10. The driver circuit 12 is configured to generate a demodulated drive signal SV and a modulated drive signal SM to drive the APG device 10, such that the APG device 10 generates sound by generating multiple air pulses at an ultrasonic pulse rate. In one embodiment, the driver circuit 12 may include, but is not limited to, the circuitry disclosed in commonly-filed U.S. Patent Nos. 12,261,567 and / or 12,107,546 to generate the signals SV and SM.

[0029] The sound generation module 22 may be located in a wearable acoustic device, i.e., a wearable device capable of generating sound, such as earbuds, earphones, hearing aids, smartwatches, smart glasses, or AR / VR / MR / XR devices (where AR / VR / MR / XR stand for augmented reality / virtual reality / mixed reality / augmented reality).

[0030] The controller 20 includes a volume control unit 200. The volume control unit 200 controls a target volume Vol tg , the drive circuit 12 generates a demodulated drive signal SV having the demodulated amplitude SVamp and a modulated drive signal SM having the modulated amplitude SMamp, and drives the APG device 10 to achieve the target volume Vol tg Achieve this.

[0031] In one embodiment, the controller 20 may be implemented as a system-on-chip (SoC), such as the QCC series from Qualcomm. The volume control unit 200 may be software or firmware (or a piece of programming code) executed by a hardware device such as the controller 20. In one embodiment, the functionality of the volume control unit 200 may be built as / into an application programming interface (API) within the SoC or within the controller 20. The volume control unit 200 may receive, for example, a target volume Vol from a higher level / layer of the program, e.g., from the application level of volume adjustment, via an API within the SoC. tg may be received, but is not limited to.

[0032] In one embodiment, the volume control unit 200 has (holds) a set of parameter curves and adjusts the target volume Vol according to the set of parameter curves. tg The amplitude parameters SVamp and SMamp corresponding to the above are output.

[0033] For example, Figure 6 shows four parameter curve sets 3a, 3b, 3c, and 3d according to an embodiment of the present application. tg , the volume control unit 200 may find the corresponding amplitude parameters SVamp and SMamp according to the parameter curve set (which may be, but is not limited to, 3a, 3b, 3c or 3d).

[0034] In one embodiment, the demodulation amplitude parameter SVamp may be the peak-to-peak voltage of the demodulation drive signal SV, denoted as SVpp. In one embodiment, the modulation amplitude parameter SMamp may be the root-mean-square voltage of the modulated drive signal SM, denoted as SMVrms. The drive circuit 12 may generate the demodulation drive signal SV and the modulated drive signal SM according to SVpp and SMVrms, but is not limited thereto.

[0035] In this application, the term "modulation (demodulation) amplitude parameter" is sometimes abbreviated to "modulation (demodulation) amplitude" for the sake of brevity.

[0036] In parameter curve set 3a, the demodulation amplitude parameter SVamp may be held constant while the modulation amplitude parameter SMamp may increase / decrease as the target volume (expressed in sound pressure level (SPL)) increases / decreases. In one embodiment, volume control 200 using parameter curve set 3a may provide the advantage of higher audio quality or fidelity (or equivalently, lower total harmonic distortion (THD)).

[0037] In parameter curve set 3b, the threshold SPL th,b Below the threshold SPL, the demodulation amplitude parameter SVamp is held constant, and the modulation amplitude parameter SMamp increases / decreases as the target volume increases / decreases. th,b Above this, the demodulation amplitude parameter SVamp increases / decreases as the target volume increases / decreases, and the modulation amplitude parameter SMamp is kept constant.

[0038] For parameter curve set 3c, the threshold SPL th,c Below the threshold SPL, the demodulation amplitude parameter SVamp increases / decreases according to the increase / decrease in the target volume, and the modulation amplitude parameter SMamp is kept constant. th,c Above this, the demodulation amplitude parameter SVamp is held constant and the modulation amplitude parameter SMamp increases / decreases as the target volume increases / decreases. In one embodiment, a volume control unit 200 using parameter curve set 3c may provide the advantage of low power.

[0039] In parameter curve set 3d, the demodulation amplitude parameter SVamp increases / decreases according to the increase / decrease of the target volume, while the modulation amplitude parameter SMamp can be kept constant, for example, at a high level. The volume control unit 200 using parameter curve set 3d can have the advantage of achieving bit-perfect or improving SQNR (signal-to-quantization-noise ratio).

[0040] As can be seen from FIG. 6, the demodulation amplitude SVamp and the modulation amplitude SMamp vary in different ways relative to the target volume.

[0041] 6 (e.g., SVamp / SMamp vs. SPL) represents a mapping relationship, which can be obtained by experiment or simulation. The volume control unit 200 can calculate the parameter curve or mapping relationship in one of the following ways: 1) by storing the mapping relationship in a memory (such as a lookup table) and referencing the memory or the lookup table to obtain the target volume Vol tg SVamp and SMamp corresponding to Vol are obtained, or 2) the mapping relationship is expressed mathematically and the target volume Vol tg , or by calculating the SVamp and SMamp corresponding to

[0042] In this application, when the volume control unit 200 has a parameter curve, it means that either the mapping relationship of the parameter curve is stored in memory in the controller 20, or the volume control unit 200 has a mathematical formula for the parameter curve and can perform calculations accordingly.

[0043] It should be noted that the parameter curve set illustrated in Figure 6 is for illustrative purposes only. The parameter curve set or parameter curve is not limited to the shape shown in Figure 6. The target volume Vol tg As long as the above is achieved, the requirements of the present invention are met.

[0044] In reality, the performance of a sound generation system with an APG device has many different aspects, and it is not easy to optimize all of them at once. For example, parameter curve set 3a may result in good sound quality but may consume more power (because SVamp / SVpp is high). Parameter curve set 3c may consume less power (because SVamp / SVpp can be made very low) but may sacrifice sound quality.

[0045] To allow a sound generation system more flexibility in achieving all aspects of performance (perhaps not simultaneously), it is possible to let the user decide which aspects to optimize. For example, one user may use the sound generation system to enjoy classical music and may not be very concerned about power consumption. In that case, the user may select a "high fidelity" mode via a user interface, e.g., a mobile application. Alternatively, another user may be concerned about power consumption but not sound fidelity / quality. In that case, the user may select a "low power" mode.

[0046] In this case, the volume control unit 200 outputs a mode signal S 1 indicating in which operation mode the sound generating module 22 operates or to which operation mode it should switch. mode The volume control unit 200 may receive the mode signal S mode A parameter curve set may be selected from the plurality of parameter curve sets according to the mode signal S, where the plurality of parameter curve sets correspond to a plurality of operation modes. mode indicates that the sound generation module is operating in high fidelity mode or is about to switch to high fidelity mode, volume control 200 may select set 3a. mode indicates that the sound generation module is operating in a low power mode or is about to switch to a low power mode, the volume control unit 200 may select set 3c.

[0047] In other words, the sound generating module 22 can operate in one of a plurality of operating modes. The volume control unit 200 may have a plurality of parameter curve sets corresponding to the plurality of operating modes, and the mode signal S mode instructs the volume control unit 200 which parameter curve set to use to obtain SVamp and SMamp.

[0048] The multiple operating modes may include a high-fidelity mode, a low-power mode, a high-lifetime mode, a low-noise mode, etc. Each operating mode has a purpose to be optimized. Although the term "high / low" includes a relative concept, the "high / low XX mode" here indicates that the purpose XX is optimized among all operating modes. For example, in the high-fidelity mode, audio quality is optimized compared to other operating modes. For example, in the high-lifetime mode, the amplitudes SVamp and SMamp are optimized to minimize the electric field stress applied to the actuator (e.g., 101A / 103A). The parameter curve of the high-lifetime mode may be designed and refined according to actual conditions.

[0049] In addition to the amplitude parameters SVamp / SMamp, the operating frequency Fv can also be a control factor for controlling / adjusting the volume. When the operating frequency Fv approaches (or is closer to) the resonant frequency Fr of the air pulse generating device, the flaps 101 / 103 have a larger displacement when the same amplitudes SVamp and SMamp are applied to the actuator, and the flap pair has a larger ΔU z It has.

[0050] This is verified by Figure 7, which shows curves of displacement gain (compared to when a direct current (DC) frequency is applied to the flap pair) versus Fr / Fv ratio (for flap pairs with different quality factors Q), where Fr / Fv → 1 means that the operating frequency Fv approaches the resonant frequency Fr for the APG device 10.

[0051] As the operating frequency Fv approaches (or becomes closer to) the resonant frequency Fr, the conductance of the virtual valve 112 (e.g., the amplitude of the conductance G(t)) increases. This is because the displacement difference ΔU z This suggests that the sound volume (and the volume of the APG device as a sound generating device) is also affected by the operating frequency Fv.

[0052] In conclusion, the volume of the APG device as a sound generating device can be adjusted by the operating frequency Fv, where Fv can be regarded as an adjustable parameter for sensitivity adjustment.

[0053] The volume control unit 200 may adjust (directly or indirectly) the operating frequency Fv to more closely approximate the resonant frequency Fr of the APG device. In other words, the volume control unit 200 may adjust a parameter such that a first difference between a first operating frequency (before adjusting the operating frequency) and the resonant frequency Fr of the APG device is greater than a second difference between a second operating frequency (after adjusting the operating frequency) and the resonant frequency Fr of the APG device. The parameter here may be, for example, the operating frequency Fv of the APG device (directly) or the Fr / Fv ratio (indirectly). In one embodiment, adjusting the operating frequency Fv to more closely approximate the resonant frequency Fr may correspond to a louder volume adjustment, a low-power mode, or a long-life mode.

[0054] On the other hand, the volume control unit 200 may adjust (directly or indirectly) the operating frequency Fv to move away from the resonant frequency Fr of the APG device. In other words, the volume control unit 200 may adjust a parameter so that a first difference between a first operating frequency (before adjusting the operating frequency) and the resonant frequency Fr is smaller than a second difference between a second operating frequency (after adjusting the operating frequency) and the resonant frequency Fr. The parameter here may be, for example, the operating frequency Fv of the APG device (direct) or the Fr / Fv ratio (indirect). In one embodiment, adjusting the operating frequency Fv to move away from the resonant frequency Fr may correspond to a low-noise mode situation, since the noise in the sound generating module 22 is observed to be lower when the operating frequency Fv is farther away from the resonant frequency Fr.

[0055] The volume control of the present invention can be performed by adjusting SVamp and Fv in addition to SMamp related to DAC (digital-to-analog converter) operation. In this application, volume control by sensitivity adjustment (e.g., by parameters SVamp and Fv) or mode selection to achieve excellent SQNR and / or power efficiency may be referred to as smart volume control. The additional (sensitivity adjustment) parameters SVamp and Fv increase the flexibility of volume control, and bit-perfect sound with excellent SQNR can be achieved.

[0056] This is because the unique features of APG-based systems directly address the limitations of conventional audio volume control. By precisely modulating air pulses via adjustable demodulation and modulation amplitudes (SVamp and SMamp), the present invention avoids the inherent SQNR degradation associated with digital bit truncation. Furthermore, the ability to control volume via the intrinsic "sensitivity" of the APG device (via SVamp or Fv) fundamentally resolves the power inefficiency and power vs. sound quality dilemma faced by conventional transducers. Multimode or mode-selective operation, enabling optimization for high fidelity, low power, or low noise, provides flexible solutions not achievable with conventional approaches.

[0057] In summary, the present invention provides a robust and superior volume control mechanism that enhances both audio fidelity and energy efficiency by utilizing SVamp, Fv and SMamp as volume adjustment parameters.

[0058] Those skilled in the art will readily observe that numerous modifications and variations can be made to the apparatus and method while retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims

1. A controller configured to control a sound generation module, said controller comprising: a volume control unit configured to determine a demodulation amplitude and a modulation amplitude corresponding to a target volume; the sound generating module includes a drive circuit and an air pulse generating device; the drive circuit generates a demodulated drive signal according to the demodulated amplitude and generates a modulated drive signal according to the modulated amplitude to drive the air pulse generating device; The air pulse generating device generates sound by generating a plurality of air pulses at an ultrasonic pulse rate.

2. The controller of claim 1 , wherein the controller is implemented by a system on a chip (SoC).

3. The controller of claim 1 , wherein the volume control is associated with an application programming interface (API).

4. The controller of claim 1 , wherein the volume control adjusts an operating frequency of the air pulse generating device corresponding to the ultrasonic pulse rate.

5. The controller of claim 1 , wherein the volume control determines the demodulation amplitude and the modulation amplitude according to a set of parameter curves.

6. The controller of claim 5 , wherein the volume control determines the demodulation amplitude and the modulation amplitude according to the set of parameter curves among a plurality of sets of parameter curves.

7. the volume control unit receives a mode signal indicating that the sound generation module is to operate in a first mode of a plurality of modes; The controller of claim 1 , wherein the volume control unit determines the demodulation amplitude and the modulation amplitude according to the target volume and the mode signal.

8. The controller of claim 7 , wherein the plurality of modes includes at least one of a low power mode, a high fidelity mode, a high life mode, and a low noise mode.

9. The controller of claim 7 , wherein the volume control determines the demodulation amplitude and the modulation amplitude according to a first set of parameter curves corresponding to the first mode of the plurality of modes.

10. The controller of claim 7 , wherein the plurality of modes corresponds to a plurality of sets of parameter curves.

11. The controller of claim 1 , wherein the volume control holds the demodulation amplitude constant and increases the modulation amplitude as the target volume increases.

12. the volume control unit increases the demodulation amplitude in accordance with an increase in the target volume when the target volume is smaller than a threshold value, and maintains the modulation amplitude at a first constant value; The controller of claim 1 , wherein the volume control unit maintains the demodulation amplitude at a second constant value when the target volume is greater than the threshold value, and increases the modulation amplitude as the target volume increases.

13. the volume control unit holds the demodulation amplitude at a first constant value when the target volume is smaller than a threshold value, and increases the modulation amplitude as the target volume increases; The controller according to claim 1 , wherein the volume control unit increases the demodulation amplitude as the target volume increases when the target volume is greater than the threshold value, and maintains the modulation amplitude at a second constant value.

14. The controller according to claim 1 , wherein the volume control unit increases the demodulation amplitude as the target volume increases, and maintains the modulation amplitude at a constant value.

15. The controller of claim 1 , wherein the demodulation amplitude and the modulation amplitude vary in different ways relative to the target volume.

16. The controller of claim 1 , wherein the sound generation module is disposed within a wearable acoustic device.

17. A controller configured to control a sound generation module, said controller comprising: Includes a volume control the sound generation module includes an air pulse generating device; the air pulse generating device generates sound by generating a plurality of air pulses at an ultrasonic pulse rate; the volume control adjusts a parameter to adjust the operating frequency of the air pulse generating device; A controller, wherein the volume of the sound generated by the air pulse generating device is adjusted by adjusting the operating frequency.

18. The controller of claim 17 , wherein the volume control adjusts the parameter so that the operating frequency is closer to a resonant frequency of the air pulse generating device.

19. The controller of claim 17 , wherein the volume control adjusts the parameter such that the operating frequency moves away from a resonant frequency of the air pulse generating device.

20. 1. A volume determination method applied to a volume control unit in a controller for controlling a sound generation module, the volume determination method comprising: determining a demodulation amplitude and a modulation amplitude corresponding to a target volume; the sound generating module includes a drive circuit and an air pulse generating device; the drive circuit generates a demodulated drive signal according to the demodulated amplitude and generates a modulated drive signal according to the modulated amplitude to drive the air pulse generating device; The method of determining volume, wherein the air pulse generating device generates sound by generating a plurality of air pulses at an ultrasonic pulse rate.

21. receiving a mode signal indicating that the sound generation module is to operate in a first mode of a plurality of modes; and determining the demodulation amplitude and the modulation amplitude according to the target volume and the mode signal.

22. 1. A volume adjustment method configured to adjust a volume of a sound generation module, the volume adjustment method comprising: adjusting an operating frequency of the air pulse generating device corresponding to the ultrasonic pulse rate; the sound generation module includes the air pulse generating device; The air pulse generating device generates sound by generating a plurality of air pulses at the ultrasonic pulse rate.

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