Abstract: The invention provides an integrated circuit. The integrated circuit receives a first signal from a microphone via a first node. In one embodiment, the integrated circuit comprises a biasing circuit and a buffering circuit. The biasing circuit is coupled between the first node and a second node, drives the microphone with a first voltage source, and filters the first signal to generate a second signal at the second node. In one embodiment, the biasing circuit comprises a first resistor, a first capacitor, and a load element. The first resistor is coupled between the first voltage source and the first node. The first capacitor is coupled between the first node and the second node. The load element is coupled between the second node and a second voltage source. The buffering circuit is coupled between the second node and a third node and buffers the second signal to generate a third signal at the third node.

Abstract: A differential microphone having a perimeter slit formed around the microphone diaphragm that replaces the backside hole previously required in conventional silicon, micromachined microphones. The differential microphone is formed using silicon fabrication techniques applied only to a single, front face of a silicon wafer. The backside holes of prior art microphones typically require that a secondary machining operation be performed on the rear surface of the silicon wafer during fabrication. This secondary operation adds complexity and cost to the micromachined microphones so fabricated. Comb fingers forming a portion of a capacitive arrangement may be fabricated as part of the differential microphone diaphragm.

Abstract: Embodiments of the present invention disclose a contact microphone for an electronic device. According to one embodiment, the electronic device includes a display lens having a front side and a backside opposite the front side, with the display lens being formed around the perimeter of a display unit. Furthermore, a contact microphone is coupled to a backside of the display lens and configured to convert acoustic signals received on the front side of the display lens.

Abstract: A mobile terminal having a dual display unit, a dual speaker and a dual microphone, and a method of controlling the dual speaker and the dual microphone thereof are provided. The method of controlling a dual speaker and a dual microphone of a mobile terminal having a dual display unit including a first body having a first display unit and first speaker on a front surface and a second display unit and second speaker on a rear surface, a second body having a first and a second microphone, and a hinge module for rotatably connecting the first body and the second body, includes determining which of the first and second display units is activated; activating, if the first display unit is activated, the first speaker; and activating, if the second display unit is activated, the second speaker.

Abstract: A microphone including a connector with a plurality of electrical contacts. The microphone interfaces with a computer system via a digital bus. The microphone can transmit data to the computer system via the connector that is related to at least one of the following: the microphone manufacturer, the microphone manufacture date, the microphone model number, the microphone serial number, the microphone frequency response, whether the microphone uses phantom power, the desired pre-amplifier gain, and the microphone dynamic response.

Abstract: An earplug that includes a piezoelectric element that converts electrical signals into oscillations; and a deformable material of which at least one segment is insertable into an external auditory canal of a person to ensure an acoustic seal by deformation, the piezoelectric element being disposed inside the deformable material and in fixed contact therewith, the deformable material being able to transmit the oscillations at a periphery and ensure conduction of the oscillations through cartilage and soft tissue of the auditory canal.

Abstract: A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.

Abstract: A microphone preamplifier, comprising a differential input (102) stage with a first and a second input terminal and an output stage with an output terminal; where the microphone preamplifier is integrated on a semiconductor substrate. A feedback circuit, with a low-pass frequency transfer function (103), is coupled between the output terminal and the first input terminal and integrated on the semiconductor substrate. The second input terminal provides an input for a microphone signal (105). Thereby a very compact (with respect to consumed area of the semiconductor substrate), low noise preamplifier is provided.

Abstract: A vented gas riser for use in a system for conducting pressurized gas through a gas carrier pipe from a gas supply source line located below ground level to a delivery point disposed above ground is provided. A fluid tight gas riser protective casing is disposed around said carrier pipe and creates a gas escape passageway in an elongate annular space between the carrier pipe and the casing. A containment chamber is disposed below ground level which creates a confined space which has, as its only egress, a fluid connection to a gas escape passageway. Any gas which leaks into the containment chamber is directed into the gas escape passageway. A riser transition head, which includes at least one vent passageway, provides a fluid connection with said gas escape passageway and with the atmosphere such that any gas which leaks into said containment chamber is directed through the gas escape passageway and through the at least one vent and into the atmosphere.

Abstract: The invention relates to a method for the manufacture of a sensor element and to a sensor element. In the method, both surfaces of a sensor film are provided with metallic electrodes. The sensor element is produced by cutting it from a larger amount of sensor element material. In the manufacture of the sensor element material, the electrodes are produced as a continuous process from roll to roll and the sensor element material is formed by laminating as a continuous process from roll to roll. At least the signal electrode consists of repeated electrode patterns (41) which are at least partially connected to each other via one or more narrow connecting strips (42), and a sensor element of a desired length and/or shape is produced by cutting the material across the region of the connecting strips.

Abstract: A wearable communication device includes a bone conduction actuator which is applicable for being in contact with a user's wrist, hand, back of the hand, finger or nail in order to transmit voice signals. The user inserts the user's finger into the user's ear canal, or touches the user's finger to a part near the user's ear, or puts the user's fingertip or nail on the user's ear canal so as to block the user's ear canal when the user uses the wearable communication device.

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: An integrated circuit (102) configured to provide a microphone output signal, comprising: a preamplifier (108) coupled to receive an input signal, generated by a first microphone member that is movable relative to a second microphone member; and a voltage pump (104) to provide a bias voltage to either microphone member.

Abstract: A piezoelectric ceramic composition includes a top-layer, a bottom-layer and at least one intermediate-layer ceramic sheets stacked to each other for sintering. An alloy layer of silver and palladium is interposed between every two ceramic sheets, and a sliver layer is coated on each exposed surface of the top-layer and the bottom-layer ceramic sheets, so as to form a positive and a negative electrode circuit therein. The piezoelectric ceramic composition with the silver layer is attached to at least one surface of a metal plate to make a piezoelectric element which is used to make a piezoelectric actuator, loudspeaker or buzzer.

Abstract: A piezoelectric vibrator having excellent shock resistance and high reliability is offered. The centers of first and second piezoelectric vibrating plates are supported by pillars on a main surface of an enclosure and nearly or substantially parallel to the main surface of the enclosure. Spacers having a Young's modulus of less than 2 GPa are mounted on both end sides of the second piezoelectric vibrating plate to prevent contact between the vibrating plates, thus preventing damage. Other spacers are mounted on the main surface of the enclosure in positions corresponding to the first-mentioned spacers to prevent contact with the main surface of the enclosure, thus preventing damage to the second piezoelectric vibrating plate.

Abstract: Method for manufacturing an electromechanical sensor element for converting mechanical forces produced by the movements and vital functions or a person into electric signals, in which method a sensor film (11) is provided with metallic electrodes (15,16) placed on either side of it, at least one of said electrodes being a signal electrode, in which method is produced by cutting off a larger amount of sensor element material, in which method in the manufacture of sensor element material the electrodes are created in a continuous roll-to-roll process, and in which method the sensor element material is produced by laminating as a continuous roll-to-roll process. At least the sensor element material consists of repeated electrode patterns and a sensor element of a desired size and/or shape is formed by cutting the material between the patterns.

Abstract: A piezoelectric vibrator having excellent shock resistance and high reliability is offered. The centers of first and second piezoelectric vibrating plates are supported by pillars on a main surface of an enclosure and nearly or substantially parallel to the main surface of the enclosure. Spacers having a Young's modulus of less than 2 GPa are mounted on both end sides of the second piezoelectric vibrating plate to prevent contact between the vibrating plates, thus preventing damage. Other spacers are mounted on the main surface of the enclosure in positions corresponding to the first-mentioned spacers to prevent contact with the main surface of the enclosure, thus preventing damage to the second piezoelectric vibrating plate.

Abstract: A local oscillation signal generator and a multi-band transceiver including the local oscillation signal generator are provided. The multi-band transceiver includes a fractional-N phased locked loop (PLL), a local oscillation signal generator, and a transmitter. The fractional-N PLL receives a reference signal and outputs an oscillation signal that is phase-locked to the reference signal. The local oscillation signal generator receives the oscillation signal and outputs a first divided signal that is obtained by dividing a frequency of the oscillation signal by a first value and a second divided signal that is obtained by dividing the frequency of the oscillation signal by a second value. The transmitter receives input signals and generates a transmitter signal using an equation f TX = ( 2 3 ? k - 1 M ) ? f VCO , based on the first divided signal and the second divided signal.

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: Embodiments of the present invention described and shown in the specification and drawings include a combination responsive to an acoustic wave that can be utilized as a dynamic pressure sensor. In one embodiment of the present invention, the combination has a substrate having a first surface and an opposite second surface, a microphone positioned on the first surface of the substrate and having an input and a first output and a second output, wherein the input receives a biased voltage, and the microphone generates an output signal responsive to the acoustic wave between the first output and the second output. The combination further has an amplifier positioned on the first surface of the substrate and having a first input and a second input and an output, wherein the first input of the amplifier is electrically coupled to the first output of the microphone and the second input of the amplifier is electrically coupled to the second output of the microphone for receiving the output signal from the microphone.

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 transducer assembly for receiving a stimulating signal and producing ultrasound therefrom at one or more frequencies, over an ultrabroad bandwidth at each frequency, includes a front mass disposed about a central axis, and a back mass disposed about the central axis, laterally offset from the front mass. The transducer assembly also includes one or more resonators disposed about the central axis and between the front mass and the back mass, including at least one electrical contact for receiving the stimulating signal. The back mass consists of a low-density material, such as aluminum, aluminum alloy, magnesium, or magnesium alloy, or any of various low-density materials known in the art. In general, the back mass is characterized by a density of less than 6.0 g/cc. In one embodiment, the front mass and the back mass are made from different materials, and the front mass includes a deviation from symmetrical symmetry.

Abstract: The invention relates to a method for the manufacture of a sensor element and to a sensor element. In the method, both surfaces of a sensor film are provided with metallic electrodes. The sensor element is produced by cutting it from a larger amount of sensor element material. In the manufacture of the sensor element material, the electrodes are produced as a continuous process from roll to roll and the sensor element material is formed by laminating as a continuous process from roll to roll. At least the signal electrode consists of repeated electrode patterns which are at least partially connected to each other via one or more narrow connecting strips, and a sensor element of a desired length and/or shape is produced by cutting the material across the region of the connecting strips.

Abstract: A piezoelectric electroacoustic transducer, including a plurality of piezoelectric layers deposited to define a deposited product, flexurally vibrates the deposited product by polarizing the entire piezoelectric ceramic layers in the same thickness direction and also by applying an alternating signal between external electrodes disposed on the front/rear major surfaces of the deposited product and an internal electrode disposed between the ceramic layers. A dummy electrode is provided between the ceramic layers outside the internal electrode via a gap, and a portion of the internal electrode is exposed at at least one side surface of the piezoelectric ceramic layers, while the dummy electrode is exposed at the other side surface of the piezoelectric ceramic layers. The external electrodes extend to the side surfaces other than the side surface at which the internal electrode is exposed.

Abstract: An acoustic system has an acoustic sensor and a processing circuit. The acoustic sensor includes a base, a microphone having a microphone diaphragm supported by the base, and a hot-wire anemometer having a set of hot-wire extending members supported by the base. The set of hot-wire extending members defines a plane which is substantially parallel to the microphone diaphragm. The processing circuit receives a sound and wind pressure signal from the microphone and a wind velocity signal from the hot-wire anemometer, and provides an output signal based on the sound and wind pressure signal from the microphone and the wind velocity signal from the hot-wire anemometer (e.g., accurate sound with wind noise removed). The configuration of the hot-wire extending members defining a plane which is substantially parallel to the microphone diaphragm can be easily implemented in a MEMS device making the configuration suitable for miniaturized applications.

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 speaker device for emitting subsonic, sonic or ultrasonic compression waves comprising a a rigid emitter plate attached to the drum, and a plurality of apertures formed within the plate which are covered by a thin piezoelectric film disposed across the emitter plate. The thin film at the apertures distends into an arcuate emitter configuration capable of constricting and extending in response to variations in the applied electrical input at the piezoelectric film to thereby create a compression wave in a surrounding environment. Parametric ultrasonic frequency input is supplied to the piezoelectric film to propagate multiple ultrasonic frequencies having a difference component corresponding to the desired subsonic, sonic or ultrasonic frequency range.

Abstract: This relates to flextensional microphones which are made up of a piezoelectric substrate having opposing surfaces, typically parallel surfaces when the substrate is crystalline or ceramic, and at least one sound receiving surface physically tied to the piezoelectric substrate. The microphones are at least partially isolated via a biocompatible material, e.g., by a covering or a coating. The inventive microphones may be subcutaneously implanted. The microphones may be used as components of surgically implanted hearing aid systems or as components of hearing devices known as cochlear implants. Preferably the microphones are used in arrays and when used as a component of a hearing assistance or replacement device, are used in conjunction with a source of feedback information, usually another microphone. The feedback information usually relates to sound re-emitted from physical portions of the ear, e.g.

Abstract: The present invention provides a vibration detector device (1) suitable for use as a cochlear implant (12). The detector device (1) comprises a substrate (2) formed and arranged for supporting a plurality of resonator bars (4). The resonator bars (4) are of a uniform length and are supported at each end (6, 8) by the substrate material (2). Each of the resonator bars (4) has a distinct resonant frequency characteristic and is arranged with a piezoelectric generator to generate a signal in response to receiving a vibration which causes the resonator bar (4) to vibrate at its resonant frequency.

Abstract: A piezoelectric electroacoustic transducer that is capable of preventing a short-circuit between an internal electrode and external electrode and also capable of preventing cracks of ceramic layers during polarization to improve a yielding rate. A piezoelectric electroacoustic transducer, including a plurality of piezoelectric layers deposited to define a deposited product, flexually vibrates the deposited product by polarizing the entire piezoelectric ceramic layers in the same thickness direction and also by applying an alternating signal between external electrodes disposed on the front/rear major surfaces of the deposited product and an internal electrode disposed between the ceramic layers. A dummy electrode is provided between the ceramic layers outside the internal electrode via a gap, and a portion of the internal electrode is exposed at at least one side surface of the piezoelectric ceramic layers, while the dummy electrode is exposed at the other side surface of the piezoelectric ceramic layers.

Abstract: The present circuit is for a resonant, regenerative switching piezomotor drive amplifier that efficiently converts electrical energy into mechanical work through a piezoelectric actuator. The actuator driver of the present invention drives the real work-producing part of the system load over a broad range of frequencies from DC to several kHz, dramatically increasing the system power efficiency and full power bandwidth. The gains in efficiency are obtained by operating the motor/amplifier system at both electrical and mechanical resonances for the system. The amplifier's efficiency is greater than 80% when driving a 1 &mgr;F piezoelectric load with a 500 V peak-to-peak signal. The available output power is greater than 20 watts continuously from DC to 2.0 kHz.

Abstract: A noise suppressing microphone employing a thin film of piezoelectric material sandwiched between two conductive layers, one of which is laminated to a flat inflexible laminate. The sandwich is embedded in a mechanical sound filter except for one exposed face which is placed in contact with a user's body for sound pickup.

Abstract: A circuit for automatically driving a mechanical device at its resonance frequency is provided. To do so, the circuit detects non-resonance driving conditions of the mechanical device being coupled to and driven by such circuit. Based on such detection, the circuit generates a signal to drive the device at its resonance frequency.

Abstract: A method of forming an ultrasound transducer having thermoformed protuberances comprises providing a substrate having a plurality of perforations of a given dimension. The perforations or apertures are formed in the substrate and operate to determine the resonance frequency associated with the transducer. A film of polymeric material capable of showing piezoelectric properties when strained in its plane and electrically biassed by a field applied in a direction normal to its faces, is then laminated onto the substrate. The film is heated to a given temperature and a pressure differential is applied between the top and bottom surfaces of the film for a sufficient time to form protuberances in the film through the apertures in the substrate.

Abstract: An acoustic sensor includes the following: a piezoelectric element constituted of a piezoelectric substance on which at least one electrode is provided, and a diaphragm on which the piezoelectric substance is mounted and supported; a membrane capable of vibrating, which is arranged in a position opposite to the diaphragm; a frame which is so horn-shaped that the interior space is enlarged from the edge of the membrane to the edge of the diaphragm; a cell constituted by arranging the frame in such a way as to house the diaphragm therein, expose the membrane to the outside, and enclose an electrically insulating liquid hermetically therein; and a lead connected to the electrode and drawn out from the electrode to the outside of the frame.

Abstract: A piezoelectric acoustic device capable of permitting an increase in area or space of an operation face section of an electronic equipment required for arranging parts for the electronic equipment, attaining small-sizing of an electronic equipment and minimizing intrusion of water and dust into a front air chamber through a drum. The piezoelectric acoustic device includes a piezoelectric vibrator including a metal vibrating plate and a piezoelectric ceramic element joined to the metal vibrating plate, a casing including a front side wall and a rear side wall arranged on both sides of the piezoelectric vibrator so as to define a space therebetween in which the piezoelectric vibrator is received, and a drum arranged on an outside of the front side wall so as to extend in a direction across the front side wall. The piezoelectric vibrator and front side wall are arranged so as to define a chamber therebetween and the drum is formed therein with a passage in a manner to communicate with the chamber.

Abstract: In a microphone having oscillation-proofing means provided between a microphone casing and a transducer unit, and output means, the microphone includes oscillation-detecting means provided in the microphone case for outputting an oscillation-detecting signal therefrom, when a microphone casing vibrates; and noise suppressor means for attenuating noise component which is contained in an acoustic electric output signal from said transducer unit, when vibration is excited by the microphone casing, based on the oscillation-detecting output signal from said oscillation-detecting means, whereby non-noise component acoustic electric signal can be outputted from output means.

Abstract: An impedance matching circuit couples a microphone's output to a radio's microphone input. A tap circuit is coupled to the microphone's output for extracting an audio signal therefrom. An amplifier circuit having DC blocking circuitry is coupled to the tap circuit. An audio transformer is also provided with its primary and secondary windings defining a turns ratio of approximately 1:1. The primary winding has a characteristic DC resistance that is less than approximately 100 ohms. The secondary winding has an impedance that is within a prescribed impedance range of the microphone input. A driver circuit is coupled between the amplifier circuit and audio transformer for continuously driving the audio transformer.

Abstract: A piezoelectric loudspeaker has a membrane and at least two flexural piezoresonators, one end of which is fixed, while the other end acts mechanically upon the membrane. The membrane is a flat membrane or a conical membrane having an aperture angle smaller than 10.degree..

Abstract: A speaker device for emitting subsonic, sonic or ultrasonic compression waves comprising a generally hollow drum, a rigid emitter plate attached to the drum, and a plurality of apertures formed within the plate which are covered by a thin piezoelectric film disposed across the emitter plate. A pressure source is coupled to the drum for developing a biasing pressure with respect to the thin film at the apertures to distend the film into an arcuate emitter configuration capable of constricting and extending in response to variations in the applied electrical input at the piezoelectric film to thereby create a compression wave in a surrounding environment. Parametric ultrasonic frequency input is supplied to the piezoelectric film to propagate multiple ultrasonic frequencies having a difference component corresponding to the desired subsonic, sonic or ultrasonic frequency range.

Abstract: An active noise control stethoscope enables a physician or paramedic to check vital signs in the presence of high background noise levels. A digital processing technique is used to remove noise from the output of a main detection sensor, the detector being impedance mismatched with air and therefore less sensitive to external airborne noise. Instead of a microphone, the detector uses a piezoceramic transflexural actuator mounted in a cylindrical piece of brass, with a polyurethane coating placed over the active side of the sensor to keep the sensor waterproof and broaden the response of the sensor. An identical sensor is placed above the device to detect background noise adjacent the device, the signals being combined to obtain a signal free of background noise. A third sensor is also used to electronically remove noise detected by the main sensor, the third sensor being positioned to pick-up noise coupled through the patient's body.

Abstract: A microphone apparatus including a vacuum-tube amplifier amplifying an electric signal converted from an acoustic signal includes a thermo-ionic cooling element having two surfaces, in which a first surface is in contact with the vacuum-tube amplifier for absorbing the heat generated from the vacuum-tube amplifier and the absorbed heat is radiated to the exterior from the second surface.

Abstract: A piezoelectric sound generator includes a piezoelectric device consisting of a metal diaphragm and a piezoelectric porcelain plate affixed to the diaphragm, a pair of connecting members having resistors connected to the piezoelectric device in series, a leakage magnetic flux coil connected in parallel to the piezoelectric device and the resistors in series, and a resin case. The resin case encases the piezoelectric device and containing the resistors, and has a spool for retaining the leakage magnetic flux coil. In addition, the resin case embraces a portion of the connecting members. This piezoelectric sound generator is manufactured by the steps of: soldering the resistors to the connecting members; forming the resin case in an insertion mold into which the connecting members have been placed, whereby a portion of the connecting members is embraced by the resin case; and attaching the piezoelectric device and the coil to the resin case.

Abstract: In applications where mechanical vibrations should not cause a microphone to produce an output signal, opposing and series connected PZT elements (A and B) are used to cancel mechanical shock or vibration that might cause an output voltage or signal. Acoustic waves cause the PZT elements to deflect in opposite directions which when the sensors (A and B) are electrically in series produce a measurable output.

Abstract: The support (17) forming the element has a diameter of a magnitude order higher than its height which is itself of a magnitude order higher than its thickness. It is rigidified by means of two membranes each formed of a composite collar including, between the support (17) and a concentric rigid crown (23, 24), an elastomer ring (22) adhered thereto and presenting an axial height of the same order of magnitude as its radial thickness. These rings provide, on the one hand, for the elastic return of the support in axial displacement and, on the other hand, for the preservation of the circularity and therefore for the inherent flatness of said support.

Abstract: The present invention provides a headrest (1C, 2C) in which a bone-conduction microphone (1B, 2B) is mounted in such a position as to be in contact with the back side of the head of the operator. The invention also provides a mobile body comprising the headrest (1C, 2C) as a constituent member and characterized in that the output of the bone-conduction microphone is used for a telephone voice or for speech recognition control of a device such as one installed on a vehicle. The invention further provides a mobile body comprising the headrest as a constituent member and characterized in that sleep of the operator is detected by the output of the bone-conduction microphone (1B, 2B).

Abstract: An electronic telephone terminal having a transmitter and a receiver, both having an approximately linear acoustic-to-electric transduction characteristics, and having a surrounding noise suppression function, and including a variable attenuator for controlling a gain of a transmission system; a noise detection device for detecting surrounding noise; and a control device for controlling the variable attenuator in such a manner that when a sound pressure level input to the transmitter exceeds a predetermined threshold value, the gain is fixedly set to a constant value, and when the input sound pressure level is equal to or below the predetermined threshold level, the gain is controlled in response to a change in the surrounding noise level detected by the noise detection device.

Abstract: A tuning apparatus comprises a piezoelectric element provided on a tuner case, and a mounting member which enable the tuning apparatus to be mounted on a musical instrument to be tuned. The piezoelectric element converts vibration provided by the musical instrument through the tuner case into an electric signal, and outputs the electric signal to a pitch calculation circuit. The tuning apparatus prevents the detection error due to a harmonic component having a larger amplitude than that of fundamental wave component by making the resonance frequency of the tuner case lower than the frequency of the lowest note of the musical instrument to be tuned.

Abstract: An ear microphone includes a bimorph piezoelectric transducer mounted on a PC board having an amplifier therein and surrounded by a helically wound spring. The piezoelectric transducer and spring are potted in a semi-soft potting compound which is formed in a shape adapted to be inserted into an external auditory ear canal to permit bone conduction to the microphone element. A cable is coupled to the amplifier through which a signal can be withdrawn for processing by electronic equipment.

Abstract: The invention relates to electroacoustic transducers and more particularly to microphones in which the conversion of an acoustic vibration into an electric voltage is provided by a piezoelectric diaphragm. The purpose of the invention is to allow transducers to be formed by mass production methods with a minimum of parts for providing the functions of embedment of the diaphragm, connections, screening, acoustic filtering and protection against damp and dust.