Abstract: An electret condenser microphone includes a case, a diaphragm electrically connected to the case, a fixed electrode plate disposed opposing the diaphragm with a spacer interposed therebetween, the fixed electrode plate being formed of a metal plate coated with a polymer film on which an electret is formed, an insulating ring for insulating the fixed electrode plate from the case, a printed circuit board (PCB) defining a back chamber with the fixed electrode plate, and an integrated base for supporting the fixed electrode plate and the PCB and electrically connecting the fixed electrode plate to the circuit component embedded in the PCB through a connecting terminal. The integrated base includes a hollow cylindrical insulating body and metal plating layers formed on the top and bottom of the insulating body. Outer diameters of the metal plating layers are less than the insulating body and are electrically connected by a conductor.

Abstract: A speaker collective substrate with component insertion hole sections and electrode sections has a plurality of speaker forming areas. An electrical speaker section, which comprises a magnetic circuit section and a vibration section, is inserted into each of the component insertion hole sections. Then, a collective lid, in which a plurality of lids have been formed for sealing the electrical speaker sections, is attached onto the speaker collective substrate. After that, the speaker collective substrate and the collective lid are divided into individual speaker forming areas along partition lines extending in the directions of the X and Y axes to form individual dynamic speakers. Thus, it is possible to mass-produce dynamic speakers with uniform quality through a collectively manufacturing process.

Abstract: A microphone isolation system. The system includes an isolation member, a support member, and at least two compliant members. The at least two compliant members mechanically support the isolation member and isolate the isolation member from vibrations. The at least two compliant members can also isolate the support member from any vibratory excitation source coupled to and/or supported by the isolation member.

Abstract: An electrostatic loudspeaker requires a high voltage DC bias power supply to bias the stators and diaphragms of electrostatic speakers. A self biased power supply eliminates the need for an external power supply by deriving a high voltage bias from the stator AC signal voltages which have been rectified and run from a high voltage tap and/or through a voltage multiplier which has a voltage limiting means.

Abstract: An acoustic pressure type sensor fabricated on a supporting substrate is disclosed. The acoustic sensor is fabricated by depositing and etching a number of thin films on the supporting substrate and by machining the supporting substrate. The resulting structure contains a pressure sensitive, electrically conductive diaphragm positioned at a distance from an electrically conductive fixed electrode. In operation, the diaphragm deflects in response to an acoustic pressure and the corresponding change of electrical capacitance between the diaphragm and the fixed electrode is detected using an electrical circuit. Two or more such acoustic sensors are combined on the same supporting substrate with an interaural flexible mechanical connection, to form a directional sensor with a small surface area.

Abstract: The present invention provides a solution to the needs described above through a microphone PCB with an integrated filter. The invention provides for an electret microphone assembly. The microphone assembly includes a multilayer printed circuit board. A field effect transistor with a gate is coupled to the electret microphone. The field effect transistor drain is coupled to provide audio frequency output to an audio output node, and the field effect transistor source is coupled to a ground. A first end of a resistor is coupled to the drain of the field effect transistor and the second end is coupled to a filter. The filter attenuates unwanted electromagnetic interference associated with a radio frequency transmitter.

Abstract: A preamplifier having extremely high input impedance amplifies the electrical signal output from an electret condenser microphone (ECM) without suffering from the effects of a DC leakage current at the input. The preamplifier circuit includes a pair of cross-coupled PN junction diodes setting the input impedance, a PMOS device, and a load resistor configured similarly to a conventional preamplifier. A capacitor is placed between the input and the cross-coupled diodes such that a DC path no longer exists to bias the cross-coupled diodes. Therefore, leakage currents are prevented from upsetting the DC operating point of the preamplifier and biasing the cross-coupled diodes. Consequently, small signal gain distortion, excessive demodulation products and increased noise can be avoided.

Abstract: A method and apparatus for substantially reducing and virtually eliminating direct current flow through the input transistor(s) of an input buffer circuit for an electret microphone is disclosed. An input transistor is provided and operably connected to an input and an output of the input buffer circuit. The input transistor has a first operating state wherein current flow occurs in a first direction and a second operating state wherein the a current flow occurs in a second direction—opposite that of the first direction. The input transistor is biased to alternately control operation between the first operating state and the second operating state. The alternating, opposing flows of current of the respective operating states cooperate to substantially reduce and virtually eliminate the flow of direct current through the input transistor(s) of the buffer circuit.

Abstract: A microphone preamplifier. An electrical signal from a microphone is received via a shielded cable by an input stage cascaded with an output stage. The input stage contains an impedance converter and a phase inverter and receives feedback that reduces input capacitance, actively shields the coaxial cable, and stabilizes the input stage. The output stage contains a buffer and output driver and provides amplified versions of the input stage output. The preamplifier contains means for transformerless phantom powering the microphone and the microphone preamplifier, for sharing current between the input and the output stages, and for limiting the frequency at the output of the microphone.

Abstract: A microphone unit capable of suppressing the sensitivity reduction due to a parasitic capacitance that occurs depending on the structure of an electret capacitor, can be realized by the following manner. Specifically, an output signal (Vout) that is the inverted output of an input signal (Vin) is inputted to an operational amplifier (OP2) that is an inverting amplifier, such that the output signal (Vout) has the same phase as the input signal (Vin) and is amplified. With an output signal (Vfb) of the operational amplifier (OP2) connected to a first electrode of a parasitic capacitor (CX), the parasitic capacitor (CX) functions as a coupling capacitor, while a feedback is applied to an electret capacitor (EC). This allows for an increase in the voltage between both terminals of the electret capacitor (EC), and thus suppresses that the sensitivity of the microphone unit is lowered due to the parasitic capacitor.

Abstract: Microphone/amplifier system in which the microphone comprises a case with an inlet opening, a diaphragm and a backplate, and the amplifier is arranged in the case and is coupled to the diaphragm/backplate system. In the case, the diaphragm forms a first partition between a first compartment containing the inlet opening to the surroundings and a second compartment accommodating the amplifier. According to the invention, the second compartment is divided by a second partition into a first and second subcompartment, while an opening of a predetermined volume is provided in the second partition, this volume having a magnitude such that air in the first subcompartment can be caused to vibrate only with sound vibrations of low frequencies. Through this feature, the frequency characteristic of the system can be influenced.

Abstract: A microphone structure comprising a microphone (M) and an electro-static discharge protector (ZD) placed close to microphone capsule (300), preferably inside it. Further the structure comprises within the microphone capsule an e.g. ladder-type filter having parallel capacitors (C31, C32, C33) and series resistors or coils (R31, Z) protecting the microphone from radio frequency disturbances. Structure parts may be on same circuit board or in same integrated circuit (IC). Structure is less susceptible to RF disturbances than known structures and its production costs are lower.

Abstract: A method of manufacturing a loudspeaker comprises: continuously forming diaphragm portions and alignment portions on a band resin film; positioning one of a frame and a protector at an upper die or lower die; aligning other alignment portions formed on the frame, the protector, or the upper or lower die having the film disposed thereon, with the alignment portion formed on the film; bonding the frame and the resin film that is to form the diaphragm; and cutting a diaphragm out of the resin film. A position of bonding the diaphragm to the frame or the protector can be easily determined by aligning the alignment portion formed on the band resin film with another alignment portion provided on the frame, the protector, or the lower or upper die on which the frame or protector is disposed. Further, a conventionally-indispensable ring can be eliminated to reduce a number of components.

Abstract: A system, more particularly a hearing aid, consisting of a microphone and a preamplifier, wherein the microphone comprises a housing having therein an opening to the surroundings, a diaphragm and a backplate, while the amplifier is coupled to the system consisting of the diaphragm and the backplate and has a field effect transistor as input element. In the housing, in a space which is bounded by, on the one hand, the diaphragm and, on the other, the housing wall, and which does not comprise the opening to the surroundings, a pressure equalization opening is present, which has a diameter such that in the audible audiospectrum it does not make an essential contribution to the suppression of low frequencies. In the input stage of the amplifier, at the output of the field effect transistor, a low-pass filter or a high-pass filter or a combination thereof is arranged. Through this measure, the frequency characteristic can be optimally influenced to suppress noise.

Abstract: A semiconductor electret capacitor microphone includes a vibration membrane, a semiconductor chip on which are formed a necessary electronic circuit, a fixed electrode, a spacer for preserving a predetermined space between the fixed electrode and the vibration membrane, and a case for enclosing the semiconductor chip and the vibration membrane in such a configuration that the fixed electrode is connected to the ground and the vibration membrane is connected to an input electrode of the semiconductor chip.

Abstract: A two-wire interface for a digital microphone circuit includes a power line and a ground line. The interface utilizes the ground line as a “voltage active line” to transmit both clock and data signals between the digital microphone circuit and a receiving circuit. The digital microphone circuit detects the clock signal on the voltage active line and uses the detected clock signal to operate an ADC to provide digital data. The digital data is used to selectively drive current back to the receiving circuit over the voltage active line. The receiving circuit detects the transmitted data by monitoring the voltage associated with a line termination. The impedance associated with the line termination is switched by the receiver circuit to modulate the clock signal on the voltage active line.

Abstract: An electrostatic speaker is constructed using a thin flexible membrane as the active member. This membrane is uniformly positioned against at least one printed circuit board containing at least one stator fixed in the PCB. Variations in structure are provided, all including at least one PCB and a membrane. In a preferred embodiment, intermeshing opposing ridges on the PCBs are adjacent to a central vibrating area of the membrane, and serve to position and tension the membrane. Attachment means connect the PCBs together, and electrical connections permit the passage of current to bias the membrane and to drive the stators to vibrate the membrane, producing acoustical output in the sonic or ultrasonic ranges. The invention also relates to the electrostatic speakers produced by this method of manufacture.

Abstract: Microphone equalization is implemented in a directional microphone system of the second or a higher order with at least three omnidirectional microphones. Initially, the signal levels of the microphone signals generated by the three omnidirectional microphones are compensated. The phase is subsequently varied in one of the three microphone signals until the signal levels of the directional microphones of the first order that are formed from the three omnidirectional microphones, are also compensated.

Abstract: A microphone circuit includes a first microphone, a second microphone, an adjustable delay unit, and a combiner. The first microphone generates a first microphone signal that includes a contribution associated with an output signal that is generated by a loudspeaker in response to an input signal. The second microphone generates a second microphone signal that includes a contribution associated with the output signal from the loudspeaker. The adjustable delay unit delays the second microphone signal relative to the first microphone signal by a delay value. The combiner combines the delayed second microphone signal and the first microphone signal to provide a combined microphone signal. The adjustable delay unit adjusts the delay value so as to reduce at least a portion of the contribution to the combined microphone signal that is associated with the output signal from the loudspeaker.

Abstract: A method for manufacturing a speaker apparatus that includes fixing a magnetic circuit to a frame so that the magnetic circuit is positioned around a central hole of the frame; positioning a coil with respect to a center pole of the magnetic circuit; connecting a damper to the coil and the frame; positioning a jig in the central hole of the frame; projecting the jig from a center hole of the center pole; engaging a positioning portion provided on a diaphragm with the jig to position the diaphragm at a predetermined position with respect to the center pole, the positioning portion being removably connected with the jig positioned in the central hole of the frame to secure the position of the diaphragm relative to the magnetic circuit during the installation; and connecting the positioned diaphragm to the coil and the frame.

Abstract: A microphone bias circuit includes a first integrated circuit (IC) pin, a second IC pin, a first resistor, and a variable supply voltage buffer. The first resistor is operably coupled to the first IC pin and a return voltage. The second IC pin is operably coupled to receive analog signals from a microphone. The variable supply voltage buffer is operably coupled to produce a buffered supply voltage based on a variable impedance setting, wherein at least one off-chip component couples the second IC pin to the first IC pin and wherein the variable supply voltage buffer provides the buffered supply voltage to second IC pin as a microphone bias voltage.

Abstract: A method and system for adjusting the frequency response characteristics of a modifiable buffer circuit (100) is disclosed. The modifiable buffer circuit (100) being generally enclosed within a housing (316). Electrical signal connections for modifying the operating state of the modifiable buffer circuit (100) are accessible outside the housing (316). The modifiable buffer circuit (100) further includes a plurality of signal inputs (234) and outputs (230), the plurality of signal inputs (234) are accessible from outside the housing. A predetermined relationship exists between the plurality of signal inputs (234) and the plurality of outputs (230). A resistor network (224) is operably connected to the plurality of outputs (230) wherein a portion of the resistor network (224) is operably disconnected from a filter network (218) in response to the plurality of signal inputs (234).

Abstract: A microphone is equipped with an element (13) for measuring the distance to a sound emitter, for example the face of an artist. The distance measurement element (13) can be part of the acousto-electric transducer (7) of the microphone, and it can be a piezo-electric ultrasound echo range finder (15, 16).

Abstract: A pressure responsive device capable of achieving thinning or miniaturization while maintaining a high performance and a method of manufacturing a semiconductor substrate for use therein. A back electrode is placed on a bottom surface of a concave formed on a central portion of a main surface of a semiconductor substrate. A peripheral edge portion of a vibrating electrode membrane is fixed on a peripheral surface surrounding the concave. In this manner, a capacitor including the back electrode/a space (air)/the vibrating electrode membrane is formed. The concave is formed by etching, and therefore a variation in depth of the concave in each apparatus is suppressed. As a result, a highly reliable and inexpensive pressure responsive apparatus is obtained.

Abstract: A condenser microphone has a conductive diaphragm 3 having an earth electrode layer 31 formed of a conductive light metal; a conductor fixed electrode 5 arranged opposite to the conductive diaphragm 3 through an air layer; an organic dielectric layer 32 formed of the organic compound provided on the boundary surface 32C side between the air layer and the conductive diaphragm 3; and a permanent electric charge layer 32A composed of ions or electrons formed in the inner portion side receding from the air layer 8 side, from a middle position in the thickness direction of the organic dielectric layer 32 in the inside of the organic dielectric layer 32.

Abstract: According to the exemplary embodiments, a voltage or current-controlled oscillator is controlled in frequency by the signal (i.e., voltage or current) from a microphone. The frequency modulated signal is applied to a direct digital discriminator that produces a digital representation of the instantaneous frequency at the desired speech sampling rate. The digital discriminator may be formed, for example, by applying the oscillator signal to a direct phase digitizing circuit along with a reference frequency and calculating a sequence of instantaneous phases of the oscillator relative to the reference frequency. The phase sequence is then applied to a digital phase locked loop (or otherwise numerically differentiated) to generate a sequence of binary words representative of instantaneous frequency and therefore representative of the speech waveform.

Abstract: A capacitor microphone includes a case having an end wall defining an opening for a sound hole, a capacitor portion comprising a diaphragm, a back plate and a spacer, the diaphragm opposing to the back plate via the spacer, the capacitor portion being accommodated in the case in such an manner as the diaphragm is placed on the side of the end wall, and a substrate accommodated in the case farther from the end wall than the capacitor portion, the substrate having an impedance conversion element mounted on a surface thereof facing the capacitor portion. A communicating opening is provided around the back plate in a position opposing to the impedance conversion element for communicating spaces on the front and back sides of the back plate. The communicating opening has a larger area than that of the top of the impedance conversion element to allow the spaces on both sides of the back plate to communicate with each other.

Abstract: A MEMS directional sensor system capable of determining direction from a microphone to a sound source over a wide range of frequencies is disclosed. By utilizing a parallel filter bank that relies on a slow wave structure in a MEMS device, such as described herein, a very small microphone, on the order of a few micrometers, can be designed with unsurpassed ability to detect a sound source location.

Abstract: A microphone includes a head and a shank and a separation board is located between the head and the shank so as to define two chambers. The first chamber has a first transferring member and the second chamber has a second transferring chamber. The two transferring members each have a sound picking device. The two transferring members generate a signal simultaneously when the microphone is hit and the two respective signals are opposite to each other so as to be eliminated. Therefore, the microphone does not generate huge noise.

Abstract: An eyewear temple structure includes an attachment portion to be attached to a frame of an eyewear, and a temple attached to the attachment portion. The temple includes a housing having a hollow space therein, a front opening, a side opening, and a bump formed adjacent to the side opening. A guide member is slidably situated in the housing and includes a second projecting portion formed at one end to rotationally engage the attachment portion, and an abutment portion formed at the other end thereof. A compression coil spring is situated in the housing between the bump and the abutment portion to urge the guide member in a direction away from the bump. The temple is rotationally attached to the attachment portion through a resilient force of the coil spring.

Abstract: An electrostatic loudspeaker requires a high voltage DC bias power supply to bias the stators and diaphragms of electrostatic speakers. A self biased power supply eliminates the need for an external power supply by deriving a high voltage bias from the stator AC signal voltages which have been rectified and run from a high voltage tap and/or through a voltage multiplier which has a voltage limiting means.

Abstract: A method for producing an electret capacitor microphone high in sensitivity and stable in acoustic characteristic. A PET film stretched with predetermined tension is bonded to a diaphragm support ring to perform stretch and fixation of a diaphragm to produce a diaphragm sub-assembly. The diaphragm sub-assembly is heated at a predetermined temperature (e.g. 200° C.) higher than a second order transition point of PET. Then, the diaphragm sub-assembly is packed in a housing. Because the diaphragm sub-assembly is heated at the predetermined temperature before packed in the housing, the stiffness of the diaphragm is reduced. Because the stiffness of the diaphragm 26 is reduced in such a manner, the tension at the time of stretch and fixation of the diaphragm can be set to a large value to prevent the diaphragm from being crinkled.

Abstract: First, a stationary electrode layer is formed over a semiconductor substrate and an integrated network is composed in a circuit element area around the stationary electrode layer by electrode wiring forming each circuit element. A spacer is arranged on a passivation film in plural places. A dummy island is formed in an area between the circuit element area and the stationary electrode layer area. Supply potential Vcc is applied to the dummy island and ground potential GND is applied to a P+-type separated area.

Abstract: The present invention relates to a semiconductor electret condenser microphone capable of being reduced in size and including an acoustic sensor 100 and a case 200 for accommodating the acoustic sensor 100, the acoustic sensor 100 has a semiconductor chip 110 forming necessary electronic circuits 111A to 111C, and opening a through hole 112 away from the electronic circuits 111A to 111C, an electrode layer 120 formed on the surface of the semiconductor chip 110 away from the through hole 112, an electret member 130 laminated away from part of the electrode layer 120 and through hole 112, and a diaphragm 140 provided with a spacing 160 to the electret member 130, in which the electrode layer 120 exposed from the electret member 130 is connected to the electrode 111a of the electronic circuit 111A through the case 200 (FIG. 6).

Abstract: A large-time-constant microphone filter which contains resistance and capacitance as its constituent and can be formed in the same semiconductor chip as a microphone unit is achieved, which results in downsizing and cost reduction of the microphone unit. A transistor of a current mirror circuit is used as a resistance of a microphone filter, utilizing a differential resistance produced by a channel length modulation effect of the transistor or an Early effect. When variations in the drain-source voltage of the transistor occur, the drain-source current of the transistor slightly varies in linear characteristics and the transistor serves a high value of resistance. Being a current mirror circuit, the microphone filter is resistant to characteristic variations due to temperature changes and can be formed in a semiconductor chip without a significant increase in chip area.

Abstract: This present invention is related to a capacitor microphone. Capacitance change of a microphone unit without polarization voltage is converted to a digital signal to obtain a sound signal in order that the microphone restricts noise and the productivity of the microphone is increased. The capacitor microphone comprises a first oscillator 2 which outputs a sound signal varying frequency in response to capacitance change of the microphone unit 1, a second oscillator 3 which outputs a tracking signal varying frequency because of a control voltage CV, a phase comparator 4 comparing phases of the sound signal and the tracking signal to output lead or lag signal, and an adder-subtracter 14 outputting digital sound data. An adding-pulse signal and a subtracting-pulse signal, which are obtained by the logical product of the lead-phase or lag-phase signal and clock pulses, are inputted to the adder-subtracter 14.

Abstract: An electret microphone circuit including an electret microphone having a field effect transistor (FET) with a gate coupled to an electret diaphragm, a drain coupled to provide audio frequency output to an audio output node, a source terminal coupled to ground, and an amplifier stage with an RLC circuit coupled to the drain for configuring the audio frequency output to desired characteristics and for obtaining microphone bias from the output node. The amplifier stage can comprise discrete transistors or integrated operational amplifiers. In another embodiment of the invention there is provided a transistor with a drain coupled to provide audio frequency output to an audio output node and for obtaining microphone bias am from said output node, a source terminal coupled to the microphone housing, and an NPN transistor current mirror stage with an RC or RLC circuit coupled to the source for configuring the audio frequency output to desired characteristics.

Abstract: The invention relates to an acoustic element and method for sound processing. The acoustic element (1) is made of a porous stator plate (2) which is either electrically conductive or plated on at least one of its surfaces to be conductive. A moving diaphragm (3, 3a, 3b) has been attached to the stator plate (2). To measure as well as produce sound pressure and particle velocity, the equipment comprises two pairs of aforementioned acoustic elements (1). Elements serving as sensors control elements serving as actuators to attenuate and absorb sound.

Abstract: Herein disclosed is an electret condenser microphone which comprises a casing member, a circuit board disposed in the casing member, an electrically insulating member disposed on the circuit board and having an outer surface opposing and spaced apart from the casing member, and an inner surface defining a central opening, an electrode plate mounted on the electrically insulating member, a plurality of electrically connecting members each intervening between the circuit board and the electrode plate to have the circuit board and the electrode plate electrically connected with each other, each of the electrically connecting members having a first portion disposed along the inner surface of the electrically insulating member, a second portion integrally formed with the first portion and radially outwardly extending from one end of the first portion, and a third portion integrally formed with the first portion and radially outwardly extending from the other end of the first portion, and a diaphragm disposed along

Abstract: There is provided a preferable impedance converter for particularly to a condenser microphone having higher input impedance without being limited by a grid resistance, and suppressing the impedance converter including an amplifier tube 2 with plate-ground, and a bias circuit 1 for generating a bias voltage applied to a grid of the amplifier tube 2, said bias circuit 1 including a diode 1A for generating a bias voltage, and a diode 1B for applying the bias voltage to the grid and thereby flowing a current toward the grid of the amplifier tube 2 so that a ham noise and a variation of a bias can be suppressed.

Abstract: A compound electrolytic loudspeaker (10) comprising two major elements: a capacitive transducer (12) and a transducer driver unit (116). The capacitive transducer (12) consist of a compound diaphragm (14) that is suspended within a frame assembly (84) and which consists of a front stator (16) having a front stator electrode (32), a rear stator (34) having a rear stator electrode (50), and a center diaphragm (54) having a diaphragm electrode (68). The electrodes interface with the transducer driver unit (116) which receives and amplifies an audio signal applied from a receiver-amplifier (126). The amplified audio signal drives the capacitive transducer (12) in synchrony with the reveived audio.

Abstract: Herein disclosed is an electret condenser microphone which comprises a casing member including a circular inlet portion, and a cylindrical side portion integrally formed with the inlet portion of the casing member, the side portion of the casing member having a first section close to the inlet portion of the casing member, and a second section remote from the inlet portion of the casing member and radially inwardly bent, a printed circuit board in the form of a circular shape and disposed in the casing member to be held in contact with the second section of the side portion of the casing member, the casing member and the printed circuit board collectively forming a cylindrical casing space, an electrode plate accommodated in the casing space of the casing member, an electrically connecting member intervening between the printed circuit board and the electrode plate to have the printed circuit board and the electrode plate electrically connected with each other, the electrically connecting member being partly

Abstract: A battery circuit for coupling a battery source to an electret microphone. The circuit includes impedance circuitry for providing appropriate bias impedance for a desired microphone sensitivity, and disconnect circuitry for automatically disconnecting the battery source from the electret microphone in response to detecting a low voltage state in order to prevent distortion and low output level of the microphone. In an alternative embodiment of the invention there is provided second impedance circuitry for driving corresponding inputs with minimal loss. In another alternative embodiment of the invention there is provided a compensation circuit which operates to extend battery source life and prevent lower output at lower voltage.

Abstract: An electroacoustic transducer of the electret type, having a backplate situated above a diaphragm, with the backplate being provided with spacers. The diaphragm is clamped on a frame-shaped carrier located at an underside of the diaphragm. The carrier is provided with supporting portions which are vertically aligned with the spacers. In one embodiment, supporting posts are formed on the supporting portions to allow the carrier to rest on a case bottom. The resulting electroacoustic transducer can be easily assembled with a reduced risk of damage.

Abstract: A microphone circuit with low distortion and having the capability of an electronic volume control. The circuit includes a capacitor microphone cap provided with a field effect transistor at the output end and a capacitor connected to the output end of the microphone cap. A resistance for supplying a driver voltage to the microphone circuit is connected to a connecting point between the microphone cap and the capacitor. Preferably a transistor adapted to generate a driver voltage for the microphone circuit or an electronic valve is connected between the microphone cap and the connecting point. The emitter of the transistor is then connected to the collector of the field effect transistor and the collector of the transistor is connected to the connecting point.

Abstract: According to the exemplary embodiments, a voltage or current-controlled oscillator is controlled in frequency by the signal (i.e., voltage or current) from a microphone. The frequency modulated signal is applied to a direct digital discriminator that produces a digital representation of the instantaneous frequency at the desired speech sampling rate. The digital discriminator may be formed, for example, by applying the oscillator signal to a direct phase digitizing circuit along with a reference frequency and calculating a sequence of instantaneous phases of the oscillator relative to the reference frequency. The phase sequence is then applied to a digital phase locked loop (or otherwise numerically differentiated) to generate a sequence of binary words representative of instantaneous frequency and therefore representative of the speech waveform.

Abstract: The problem addressed by the invention, to develop a microphone with assoted amplifier which has a better dynamic response than analog microphones, requires less space, can replace analog microphones by using cables already in place, and has a low-cost construction, is solved by the invention in that the microphone is made up of an electroacoustic transducer, two analog-digital converters, two preamplifiers connected to the output of the electroacoustic transducers on the one hand and on the other hand each with preamplifiers connected each to an analog-digital converter, and with a driver stage connected to the analog-digital converters for a two-channel digital audio format and in that the amplifier is made up of a receiver for a two-channel digital audio format and a signal processor which generates a one-channel signal from the two-channel audio format as an image of the signal of the electroacoustic transducer. The field of application is in musical production. The invention is illustrated by FIGS.

Abstract: In one embodiment of the invention there is provided an electret microphone circuit including an electret microphone including a field effect transistor (FET) having a gate coupled to an electret element, a drain coupled to provide audio frequency output to an audio output node, and a source coupled to ground via a first resistor so as to reduce drain current swings; and an RLC circuit coupled to the drain for configuring the audio frequency output from the drain to desired characteristics. In an alternative embodiment there is provided a circuit coupled to said FET for operating said FET in a source follower mode so as to create low output impedance. In another embodiment of the invention there is provided a method of improving performance of an electret microphone, the microphone including a field effect transistor (FET) having a gate coupled to an electret element, a drain coupled to provide audio frequency output to an audio output node, and a source.

Abstract: A microphone has a diaphragm which vibrates in response to sound waves and a proximately positioned charge carrying circuit for dynamically controlling a compliance of the diaphragm. A micromachined microphone has a substrate, a compliant silicon membrane, and a charge carrying circuit positioned between the substrate and the membrane. A charge applied to the charge carrying circuit controls the compliance of the membrane thereby controlling operating characteristics of the microphone, such as dynamic range and frequency response.

Abstract: An ultrasonic capacitance transducer having a sealed membrane supported above a conductive substrate by thin insulating material to form a sealed evacuated cavity whereby the transducer can operate immersed in fluid.