Abstract: An air-pulse generating device includes a membrane structure, a valve structure, and a cover structure. A chamber is formed between the membrane structure, the valve structure and the cover structure. An air wave vibrating at an operating frequency is formed within the chamber. The valve structure is configured to be actuated to perform an open-and-close movement to form at least one opening. The at least one opening connects air inside the chamber with air outside the chamber. The open-and-close movement is synchronous with the operating frequency.

Abstract: A sound producing device is provided. The sound producing device comprises a substrate; and a membrane pair, disposed on the substrate, comprising a first membrane and a second membrane; wherein when a driving voltage is applied on the membrane pair, the first membrane and the second membrane deform toward each other, such that air between the first membrane and the second membrane is squeezed outward and an air pulse is generated toward a direction away from the substrate.

Abstract: A linearity compensation method for a sound producing device (SPD) includes steps of: applying a test signal on a first SPD; obtaining an acoustic measurement result generated from the first SPD according to the test signal; generating a compensation curve according to the acoustic measurement result; and performing a linearity compensation operation on a second SPD according to the compensation curve.

Abstract: An acoustic transducer is configured to perform an acoustic transformation. The acoustic transducer is disposed within a wearable sound device or to be disposed within the wearable sound device. The acoustic transducer includes at least one anchor structure, a film structure and an actuator. The film structure is disposed within a first layer and anchored by the anchor structure disposed within a second layer. The actuator is disposed on the film structure, and the actuator is configured to actuate the film structure to form a vent temporarily. The film structure partitions a space into a first volume to be connected to an ear canal of a wearable sound device user and a second volume to be connected to an ambient of the wearable sound device. The ear canal and the ambient are to be connected via the vent temporarily opened when the film structure is actuated.

Abstract: A sound producing package structure configured to produce sound includes a substrate, a sound producing component and a conductive adhesive layer. The sound producing component is disposed on the substrate, and the sound producing component is configured to generate an acoustic wave corresponding to an input audio signal. The conductive adhesive layer is disposed between the substrate and the sound producing component by a surface mount technology.

Abstract: An acoustic testing method includes providing an electrical signal to a wafer, receiving a sound wave generated by the acoustic transducer according to the electrical signal, and generating a sensing result for determining an acoustic functionality of the acoustic transducer. The wafer includes a plurality of acoustic transducers, and the electrical signal is provided to an acoustic transducer within the wafer.

Abstract: An air-pulse generating device includes a membrane structure, a valve structure, and a cover structure. A chamber is formed between the membrane structure, the valve structure and the cover structure. An air wave vibrating at an operating frequency is formed within the chamber. The valve structure is configured to be actuated to perform an open-and-close movement to form at least one opening. The at least one opening connects air inside the chamber with air outside the chamber. The open-and-close movement is synchronous with the operating frequency.

Abstract: An air-pulse generating device includes a membrane structure, a valve structure, and a cover structure. A chamber is formed between the membrane structure, the valve structure and the cover structure. An air wave vibrating at an operating frequency is formed within the chamber. The valve structure is configured to be actuated to perform an open-and-close movement to form at least one opening. The at least one opening connects air inside the chamber with air outside the chamber. The open-and-close movement is synchronous with the operating frequency.

Abstract: An air-pulse generating device includes a membrane structure, a valve structure, and a cover structure. A chamber is formed between the membrane structure, the valve structure and the cover structure. An air wave vibrating at an operating frequency is formed within the chamber. The valve structure is configured to be actuated to perform an open-and-close movement to form at least one opening. The at least one opening connects air inside the chamber with air outside the chamber. The open-and-close movement is synchronous with the operating frequency.

Abstract: An audio device includes an electroacoustic convertor and a differential amplifier. The electroacoustic convertor has a first output terminal and a second output terminal. A first polarity of a first capacitance variation corresponding to the first output terminal is opposite to a second polarity of a second capacitance variation corresponding to the second output terminal. The first capacitance variation and the second capacitance variation are associated with a magnitude of acoustic pressure. The differential amplifier has a first input terminal coupled to the first output terminal and a second input terminal coupled to the second output terminal.

Abstract: A filter is disclosed. The filter includes at least one first multiplication approximation unit, for approximating at least one first multiplication operation corresponding to at least one first coefficient with at least one first bit-wise shift operation; and at least one second multiplication approximation unit, for approximating at least one second multiplication operation corresponding to at least one second coefficient with a plurality of second bit-wise shift operations and at least one addition operation.

Abstract: A testing apparatus including a testing platform, a loading device, a testing-signal generating device, a sound sensing device, a control unit, and an unloading device is disclosed. The loading device is configured to load a plurality of under-test devices to the testing platform. The testing-signal generating device is configured to generate at least one testing signal. The plurality of under-test devices receives the at least one testing signal and produces at least one testing sound-according to the at least one testing signal. The sound sensing device is configured to receive the at least one testing sound. The control unit controls the unloading device to unload the plurality of under-test devices from the testing platform and controls the unloading device to categorize the plurality of under-test devices into a plurality of groups according to the at least one testing sound received by the sound sensing device.

Abstract: A bidirectional charging and discharging circuit is coupled between a voltage source and a capacitive load and configured to drive the capacitive load. The bidirectional charging and discharging circuit includes a first switch, comprising a first terminal coupled to the voltage source; a second switch, comprising a first terminal coupled to a second terminal of the first switch, and a second terminal coupled to a ground; an inductor, comprising a first terminal coupled to the second terminal of the first switch and the first terminal of the second switch; a third switch, comprising a first terminal coupled to a second terminal of the inductor, and a second terminal coupled to a first terminal of the capacitive load; and a fourth switch, comprising a first terminal coupled to the second terminal of the inductor and the first terminal of the third switch, and a second terminal coupled to a ground.

Abstract: An acoustic transducer is disposed within a wearable sound device or to be disposed within the wearable sound device. The acoustic transducer includes a first anchor structure and a first flap. The first flap includes a first end and a second end. The first end is anchored by the first anchor structure, and the second end is configured to perform a first up-and-down movement to form a vent temporarily. The first flap partitions a space into a first volume to be connected to an ear canal and a second volume to be connected to an ambient of the wearable sound device. The ear canal and the ambient are connected via the vent temporarily opened.

Abstract: A crossover circuit, disposed within a sound producing device including a first sound producing cell driven by a first driving signal and a second sound producing cell driven by a second driving signal, includes a first filter receiving an input signal at an input terminal of the first filter, a first subtraction circuit, and a second filter coupled between the output terminal of the first filter and the second input terminal of the first subtraction circuit. A first input terminal of the first subtraction circuit is coupled to the input terminal of the first filter; a second input terminal of the first subtraction circuit is coupled to an output terminal of the first filter. The crossover circuit produces the first driving signal and the second driving signal according to a first output signal of the first subtraction circuit and a second output signal of the first filter respectively.

Abstract: A signal density modulation (SDM) encoder includes a first subtractor, a sigma circuit and a multi-bit quantizer. The first subtractor is used for receiving an input signal. The sigma circuit is coupled to the first subtractor. The multi-bit quantizer, coupled to the first subtractor and the sigma circuit, is configured to generate an output signal. The sigma circuit or the multi-bit quantizer produces a first feedback signal to the first subtractor. The first subtractor performs a subtraction operation according to the first feedback signal and the input signal, and generates a delta signal. The sigma circuit performs an operation on the delta signal, such that the SDM encoder has a noise transfer function having a high pass filtering effect. The noise transfer function is a ratio of a quantization error brought by the multi-bit quantizer with respect to the input signal. The output signal has more than two levels.

Abstract: A driving circuit is disclosed. The driving circuit includes a charging circuit, coupled between a voltage source and a load, configured to form a first current from the voltage source to the load; and a discharging circuit, coupled between the voltage source and the load, configured to form a second current from the load back to the voltage source.

Abstract: A filter is disclosed. The filter includes at least one first multiplication approximation unit, for approximating at least one first multiplication operation corresponding to at least one first coefficient with at least one first bit-wise shift operation; and at least one second multiplication approximation unit, for approximating at least one second multiplication operation corresponding to at least one second coefficient with a plurality of second bit-wise shift operations and at least one addition operation.

Abstract: A method, applied in a driving circuit including a bidirectional circuit coupled between a voltage source and a load, includes receiving a feedback signal from the load and an input signal; generating a plurality of pulse width modulation (PWM) signals according to the input signal and the feedback signal; driving the load by the bidirectional circuit according to the plurality of PWM signals such that the input signal and the feedback signal are substantially proportional to each other. The input signal is a time varying signal. The step of generating a PWM signal among the plurality of PWM signals according to the input signal and the feedback signal includes determining a difference according to the input signal and the feedback signal; and generating the PWM signal with a pulse width. The pulse width is determined according to the difference.

Abstract: A package structure includes a housing and a sound producing chip. The sound producing chip is disposed within the housing. The sound producing chip includes a membrane and an actuator. The membrane includes a coupling plate and a spring structure connected to the coupling plate. The actuator is configured to receive a driving signal to actuate the membrane. The spring structure is situated between the coupling plate and the actuator. The coupling plate is actuated to move by the actuator via the spring structure.