Abstract: The invention provides a beam forming method for a small array microphone apparatus to generate cone beam pattern by processing a combined bi-directional beam pattern of two virtual bi-directional microphones formed through at least three omni-directional microphones arranged in an L-shape. The invention also provides a small array microphone apparatus using the beam forming method according to the invention to suppress noise by processing a combined bi-directional beam pattern of two virtual bi-directional microphones formed through at least three omni-directional microphones arranged in an L-shape, thereby outputting a clear audio signal with cone beam pattern.

Abstract: The invention provides an audio interface device and method to acquire audio signal from either an analog or digital microphone through a common connector. The audio interface comprises a connector, electrically connected with a microphone plugged thereinto, an analog readout circuit, acquiring an analog audio signal from an analog microphone, a digital readout circuit, acquiring a digital audio signal from a digital microphone, and a decision circuit, selectively connecting the analog or digital readout circuit to the connector to acquire the analog or digital audio signal respectively according to whether the microphone plugged into the connector is analog or digital.

Abstract: A hands-free voice communication apparatus includes a speakerphone and earpiece combo, a digital signal processing (DSP) module, and a communication module. The hands-free apparatus may be used as a speakerphone or an earpiece. The speakerphone and earpiece combo includes a loudspeaker and one or multiple microphones. The loudspeaker provides an acoustic output. Each microphone receives an acoustic input and provides an input signal. The DSP module performs digital signal processing on the input signals from the microphones and provides an output signal for the loudspeaker. The DSP module may perform digital signal processing with different sets of parameters for the speakerphone and earpiece modes. The communication module provides communication between the hands-free apparatus and a communication device, e.g., a cellular phone or a wireless PDA.

Abstract: A voice recognition system and method thereof. The communication system comprises a setup controller, a voice recognition controller, and an application controller. The setup controller receives a voice keyword table including a voice recognizable keyword and a corresponding application instruction. The voice recognition controller, coupled to the setup controller, receives the voice keyword table from the setup controller, receives a first voice input, and matches a first voice input to the voice recognizable keyword to determine the corresponding application instruction. The application controller, coupled to the voice recognition controller, receives and performs the corresponding application instruction. The setup controller, the voice recognition controller, and the application controller communicate through wireless communication.

Abstract: A phase lock loop (PLL) circuit is provided. A voltage controlled oscillator (VCO) generates an output clock signal based on a control voltage. A controller provides a first digital control word, a second digital control word and a loop factor. A frequency modifier is coupled to the output clock signal, controlled by the controller to divide the output clock signal by the loop factor to generate a feedback frequency. A charge pump is controlled by the up signal and down signal to generate a charge pump current, comprising a first digital to analog converter (DAC) to generate a first current based on the first digital control word when the up signal is asserted. A second DAC generates a second current based on a second digital control word when the down signal is asserted. The controller defines a first relationship between the first digital control word and the loop factor, and the controller defines a second relationship between the second digital control word and the loop factor.

Abstract: The invention provides an Internet communication device. The Internet communication device plays a remote audio signal received via a network and transmits an audio signal back to the remote party to complete the communication. The Internet communication device comprises a line-in speech detection module and a line-in channel control module. The line-in speech detection module detects whether the remote audio signal is speech or not to generate a remote speech detection result. The line-in channel control module then attenuates the remote audio signal if the remote speech detection result indicates that the remote audio signal is not speech, thus, all noise including non-stationary noise is removed from the remote audio signal.

Abstract: A microphone apparatus is provided, including a body, a main microphone and a reference microphone. The main microphone and a reference microphone are disposed on the body for receiving a sound from a source and a noise from other than the source, wherein the main microphone and the reference microphone are arranged vertically towards the source.

Abstract: An audio processing apparatus is provided, comprising: a main microphone for receiving sounds from a source and noises from non-source sources and generating a main input; a reference microphone for receiving the sounds and the noises and generating a reference input; a short-time Fourier transformation (STFT) unit for applying short time Fourier transformation to convert the main input of a time domain signals into a main signal of a frequency domain and convert the reference input of the time domain signals into a reference signal of the frequency domain; a sensitivity calibrating unit for performing sensitivity calibration on the main signal and the reference signal and generating a main calibrated signal and a reference calibrated signal; and a voice active detector (VAD) for generating a voice active signal according to the main calibrated signal, the reference calibrated signal and a direction of arrival (DOA) signal.

Abstract: The invention provides a microphone circuit. In one embodiment, the microphone circuit comprises a transducer, a biasing resistor, a pre-amplifier, and a switch circuit. The transducer is coupled between a ground and a first node for converting a sound into a voltage signal output to the first node. The biasing resistor is coupled between the ground and the first node. The pre-amplifier is biased with a biasing voltage and coupled between the first node and a second node, and amplifies the voltage signal to obtain an output signal at the second node. The switch circuit is coupled between the first node and the ground, couples the first node to the ground when the microphone circuit is reset, and decouples the first node from the ground after a voltage status of the microphone circuit is stable, thus clamping a voltage of the first node to the ground to prevent generation of a popping noise when the microphone circuit is reset.

Abstract: An audio processing circuit is provided, receiving a microphone signal from a microphone to output a differential signal. A preamplifier receives the microphone signal to output a first preamplified voltage and a second preamplified voltage. A gain stage receives the first preamplified voltage and the second preamplified voltage to output the differential signal comprising a first differential output and a second differential output. In the preamplifier, a first operational amplifier is provided. A first voltage controlled current source is controlled by the output end of the first operational amplifier to provide a first current. A first transistor has a gate coupled to a ground voltage supply, a source coupled to the first voltage controlled current source for receiving the first current, and a drain coupled to a voltage ground. Likewise, a second voltage controlled current source and a second transistor are presented symmetrically to render the differential output.

Abstract: A phase lock loop (PLL) circuit is provided. A voltage controlled oscillator (VCO) generates an output clock signal based on a control voltage. A controller provides a first digital control word, a second digital control word and a loop factor. A frequency modifier is coupled to the output clock signal, controlled by the controller to divide the output clock signal by the loop factor to generate a feedback frequency. A charge pump is controlled by the up signal and down signal to generate a charge pump current, comprising a first digital to analog converter (DAC) to generate a first current based on the first digital control word when the up signal is asserted. A second DAC generates a second current based on a second digital control word when the down signal is asserted. The controller defines a first relationship between the first digital control word and the loop factor, and the controller defines a second relationship between the second digital control word and the loop factor.

Abstract: An array microphone system includes a first omni-directional microphone, a second omni-directional microphone, a gain control, and a beam former. The first omni-directional microphone faces a first direction. The second omni-directional microphone faces a second direction opposing the first direction. When receiving sound, the first omni-directional microphone and the second omni-directional microphone respectively generate a first signal and a second signal. The gain control amplifies the second signal to transform into a third signal, wherein strength of the third signal is equal to that of the first signal when the sound comes from the first direction. The beam former separates an in-beam sound signal and an out-beam sound signal from the first signal and the third signal.

Abstract: A multi-microphone capsule includes a housing, a plurality of microphones disposed in the housing, and an acoustic seal also disposed in the housing, wherein the microphones include an omni-directional microphone, a uni-directional microphone, or combinations thereof. The microphones are placed front-and-back or side-by-side, or a part of the microphones are placed side-by-side and the other microphones are placed front-and-back with the part of the microphones.

Abstract: A broadside small array microphone beamforming unit comprises a first omni-directional microphone to generate a signal X1(t), a second omni-directional microphone to generate a signal X2(t), a first delay unit delaying the signal X1(t) to generate a signal X1(t?T), a second delay unit delaying the signal X2(t) to generate a signal X2(t?T), a first substrator subtracting the signal X1(t?T) from the signal X2(t) to generate a signal R(t)=X2(t)?X1(t?T), a second substrator subtracting the signal X2(t?T) from the signal X1(t) to generate a signal L(t)=X1(t)?X2(t?T), a third delay unit delaying the signal R(t) to generate a signal R?(t)=R(t?D), a gain function unit convoluting the signal L(t) with a gain function G(t) to generate a signal L?(t)=L(t)*G(t?i), and a substrator subtracting the signal L?(t) from the signal R?(t) to generate a signal B?(t)=R?(t)?L?(t).

Abstract: An audio apparatus is provided, receiving a reference voltage and an input signal to generate an output signal. In the audio apparatus, a compensation circuit, generates a compensated reference voltage based on the input signal, the reference voltage and the output signal. A class AB power amplifier receives the compensated reference voltage to amplify the input signal into the output signal.

Abstract: An audio apparatus is provided, receiving a reference voltage and an input signal to generate an output signal. In the audio apparatus, a compensation circuit, generates a compensated reference voltage based on the input signal, the reference voltage and the output signal. A class AB power amplifier receives the compensated reference voltage to amplify the input signal into the output signal.

Abstract: A microphone array system and a method implemented therefore are provided. A first microphone having a first sensibility receives a sound source to generate a first signal. A second microphone is deposited at a distance from the first microphone, having a second sensibility for receiving the sound source to generate a second signal. A comparator subtracts the first signal and the second signal to generate a difference signal. An analyzer estimates an incident angle of the sound source to determine a compensation factor based on the first signal and the difference signal. A gain stage adjusts a gain of the difference signal based on the compensation factor to output an output signal.

Abstract: The invention provides a full-duplex communication device. In one embodiment, the full-duplex communication device comprises a first adaptive filter, a second adaptive filter, a channel decoupling module, and a frequency processing module. The first adaptive filter having a first tap length filters out echoes of a far-end talker from a first near-end signal carrying voices of a near-end talker according to a far-end signal carrying voices of the far-end talker to obtain a second near-end signal. The second adaptive filter having a second tap length less than the first tap length filters out echoes of the far-end talker from the first near-end signal according to the far-end signal to obtain a third near-end signal. The channel decoupling module processes the second near-end signal to generate a fourth near-end signal and subtracts the second near-end signal from the third near-end signal to obtain a fifth near-end signal.

Abstract: An MEMS microphone package includes a circuit board and an MEMS microphone chip. The MEMS microphone chip, mounted on the circuit board, includes a substrate, an MEMS transducer formed on the substrate, and a readout circuit also formed on the substrate. The MEMS transducer generates a sound signal according to sound pressure variations. The readout circuit reads the sound signal from the MEMS transducer.

Abstract: MEMS microphone packages and fabrication methods thereof are disclosed. A MEMS microphone package includes a casing with a conductive part disposed over a substrate, to enclose a cavity. A MEMS acoustic sensing element and an IC chip are disposed inside the cavity. An opening with an acoustic passage connects the cavity to an ambient space. A first ground pad is disposed on a backside of the substrate connecting to the conductive part of the casing through a via hole of the substrate. A second ground pad is disposed on the backside of the substrate connecting to the MEMS acoustic sensing element or the IC chip through an interconnection of the substrate, wherein the first ground pad and the second ground pad are isolated from each other.