Abstract: An acoustic signal receiving apparatus comprising a housing having an acoustically reflecting surface and a directional acoustic sensor unit having first-order gradient characteristics. The sensor unit is coupled to the housing with use of a retractable member having a retracted position and an extended position. When the member is extended, the sensor unit is positioned relative to the reflecting surface such that the acoustic interaction between the sensor unit and the reflecting surface causes the output of the sensor unit to have second-order gradient response characteristics. In accordance with one illustrative embodiment, in a notebook computer with a "flip-back" lid, the sensor element automatically extends to the desired position when the lid is opened, and automatically retracts to be flush with the housing surface when the lid is closed.

Abstract: An acoustic transducer including an acoustical reflecting surface of a finite dimension and at least one sensor having an output which produces a first-order differential response pattern. The sensor is located proximate to the reflecting surface, wherein acoustical waves propagating from the reflecting surface, acoustically interact with the sensor to produce a second-order differential response pattern at the output of the sensor at a predetermined frequency. The second-order differential response pattern at the output of the sensor occurs at the predetermined frequency when the finite dimension of the reflecting surface is at least one-half of an acoustic wavelength.

Abstract: A remote microphone display select system (200) used with a two-way radio (201) for controlling the orientation of displayed information includes a remote microphone (101) which is electrically connected to a display driver (203). A hall effect switch (207) is used with the display driver (203) and acts to alter the orientation of displayed information on a display (106) to either a first orientation or second orientation when the hall effect switch (207) is disabled.

Abstract: Noise cancelling microphone construction for placement in a full coverage style helmet to secure and hold a noise cancelling microphone in the plenum between the inner liner and outer shell of the helmet, the construction having a front boot and a rear boot. The front boot has a speech receiving front open sleeve leading to front ports of the microphone, a flat annular flange attached to a cylindrical end of the front sleeve, and a second sleeve attached at one of its cylindrical ends to the other side of the flange, the second sleeve securing the front part of the microphone, the flange and second sleeve encompassing an opening in the helmet inner liner. A box formed on the front sleeve receives noise in the helmet environment, passes the noise through an opening in the annular flange and through the opening in the helmet inner liner.

Abstract: A sound receiving and sound reproduction apparatus includes a microphone and loudspeaker. The microphone has a cylindrical transducer housing with a centre section and two end sections. The centre section has elliptical and faces that converge mirror-symmetrically downwardly and towards the front of the microphone. The end sections are solid blocks that are spaced from the centre section and have similarly oriented end faces. In the loudspeaker, there are three components, a centre unit with centre and end sections spaced slightly along a common axis and two end components spaced to opposite ends of the centre unit. In each case, the speakers radiate through elliptical gaps that converge upwardly to a centre plane of the loudspeaker unit. Periodic chambers are connected to each of the units of the loudspeaker.

Abstract: A microphone mounting structure including a keyboard having defining a horizontal bottom chamber near the rear side and a plurality of equally spaced vertical locating grooves inside the horizontal bottom chamber, a slide carrier slidably mounted in the horizontal bottom chamber of the keyboard, the slide carrier having a pair of vertical locating ribs detachably forced into engagement with the vertical locating grooves of the keyboard, and a supporting block at the front side, the supporting block having a microphone holder mounting hole and two locating holes spaced at an angle around the microphone holder mounting hole, a microphone holder having a mounting rod coupled to the microphone holder mounting hole of the supporting block of the slide carrier, a locating rib forced into engagement with one locating hole of the supporting block of the slide carrier, and a plug hole spaced from the mounting rod at right angles, and a microphone mounted in the plug hole of the microphone holder.

Abstract: A directional microphone intended for use in a computer visual display monitor, and methods for construction of same. The integral directional microphone assembly comprises a cardioid electret microphone capsule retained therein by acoustically transparent foam. The microphone housing is mounted internally within a display monitor housing facing the user and adjacent to the top surface of the monitor housing. The microphone housing comprises a frontal opening and a plurality of nonfrontally facing openings which together maximally preserve sound pressure gradient applied to the microphone capsule, resulting in a hypercardioid spatial response.

Abstract: This invention minimizes the space required for a speaker system for a multimedia personal computer display on a desktop. The speaker system has a very thin shape, moderate cost, very good impulse and phase response for a crisp sonic detail and good directionality for use by a single listener seated in front of the multimedia personal computer display without disturbing others nearby. Each component of the speaker system is attached to or incorporated in the right or left side of the computer display. Each component comprises a plurality of small speakers arranged in a vertical, linear array. Preferably, each plurality includes a small folded waveguide which is acoustically coupled to the rear of each of the speakers. The folded waveguide is in a unique sheet configuration and enables directional ports in a treble component and a folded variable impedance maze in a base waveguide. The speaker system provides the required shape, clarity and listener isolation needed in the personal multimedia market.

Abstract: In a small-sized pressure gradient type microphone apparatus, a plurality of omni-directional microphone units are encased within a microphone holder. A plurality of acoustic passages having first and second ends are provided within the microphone holder for coupling the sound inlets of the plurality of omni-directional microphone units respectively to an outer space of the microphone holder. The second ends of the acoustic passages opened to the outer space of the microphone holder are arranged to be apart from each other at distances larger than distances between the sound inlets of the corresponding microphone units coupled at the first ends of the acoustic passages.

Abstract: An air-borne converting device and a solid-borne converting device is provided in a case. The air-borne converting device has a loudspeaker for converting an electric signal into an air-borne sound, and a microphone for converting air-borne sound into an electric signal. The solid-borne device has a loudspeaker for converting an electric signal into solid-borne sound and a microphone for converting solid-borne sound into an electric signal.

Abstract: A unitarily molded seal membrane (310) includes an integral microphone support (304) which includes a diaphragm (306). A cavity wall (406) is located about said diaphragm (306) on one side of the seal membrane (310). The cavity wall (406) defines a cavity area (410) for receiving a microphone (504). The cavity wall aligns the diaphragm (306) in front of the microphone (504), thereby allowing for environmental sealing of the microphone (504).

Abstract: An acoustic sensor for measuring acoustic waves contained in fluid flow flowing over the sensor. The acoustic sensor reduces any unwanted self-noise associated with the flowing fluid by providing a nose cone having proper aerodynamic properties and by positioning the diaphragm of a microphone of the sensor at a location where any unwanted noise is at a relatively low level. The nose cone has a rounded, blunt or even sharp tip neither of which creates any major disturbances in the flowing fluid which it intercepts.

Abstract: The length (or the number of taps) of an adaptive finite impulse response (AFIR) filter is continuously modified to produce optimal echo cancellation. In accordance with one illustrative embodiment, this modification is performed by increasing or decreasing the number of delayed samples which are used to generate an echo estimate. More specifically, the number of samples used to generate the echo estimate is determined by selecting a trial number of samples and operating the filter for a sufficient length of time to allow the tap weights in the filter to stabilize. The tap weights are then examined to determine whether the taps at the end on the filter contribute at least a first threshold amount to the echo estimate. If not, the number of samples used in the filter is reduced and the process repeated. If the taps at the end of the filter contribute more than a second threshold amount, the number of samples is increased and the process is repeated.

Abstract: A sealed microphone assembly is disclosed including a microphone (120), a microphone housing (110) having a cavity (116) being resonant at an audio frequency range, and a sealing membrane (130). The sealing membrane 130 covers the cavity 116, thereby making the microphone assembly (100) fully sealed. The attenuation caused by sealing the microphone assembly (100) is compensated by the resonant characteristic of the cavity (116). The cavity (116) also includes one or more apertures (112) for creating a bandpass response.

Abstract: An acoustic sensor for use in a typical atmospheric condition, which contains both winds and turbulence, such as a wind and turbulence encountered on the exterior surface of a moving airborne flight vehicle includes a probe housing having a streamlined shape and a set of indentations in the exterior surface thereof extending inwardly located at a particular longitudinal location, radial airflow passages nested in respective ones of the concave indentations, the passages merging at a central manifold of the passages, wherein the particular longitudinal location is such as to minimize noise attributable to fluctuations in the wind in a longitudinal direction, and wherein the concave indentations have indentation depths such as to minimize noise attributable to wind transverse to the probe.

Abstract: A camcorder having a loudspeaker function has a recording device and includes an input device for receiving an external sound and converting it into a first electric signal and for receiving a sound from a user and converting it into a second electrical signal. The input device is preferably movable between an extended position and a retracted position. Sound processing means are provided and coupled to a speaker for outputting an amplified sound through the speaker. A switching device is provided for sending the first electrical signal to the recording device when the second input device is in the retracted position and for sending the second electrical signal to the sound processing device when the second input device is in the extended position.

Abstract: Briefly, according to the invention, a noise-cancelling microphone apparatus 302 is disclosed. The microphone comprises a housing 510 and a sound transducer 502 mounted within the housing 510. The housing has first 514 and second sides 512 and the transducer 502 has first 304 and second sound ports 308 coupled to the first 514 and second sides 512 of the housing respectively. The microphone 302 also includes a mounting clip 310 coupled to one side of the housing 512 in the proximity of one of the sound ports 308. The mounting clip 310 is intended for mounting the microphone 302 to a user so as to substantially close the sound port 308 when microphone 302 is attached.

Abstract: Briefly, according to the invention, a microphone apparatus (100) for converting sound waves to electrical signals is described. The microphone apparatus (100) includes a switch (118) for initiating the occurrence of an event. The switch (118) being substantially covered by a cap (102). The microphone apparatus (100) also includes a microphone port (114) disposed substantially behind the cap (102), thus minimizing the obstruction of the microphone port (114).

Abstract: An improved noise cancelling apparatus is disclosed combining a unique directional noise cancelling microphone structure with a noise reducing, signal shaping electronic circuit. The microphone structure simultaneously receives two input signals; a first signal containing only ambient noise and a second signal containing both ambient noise and a voice signal. The microphone structure cancels the two noise components and transmits the voice signal into an electrical signal. The electronic circuit further processes the electrical signal to suppress any noise components not cancelled by the microphone structure. The electronic circuit also functions to enhance the high frequency components of the voice signal to provide a richer, more pleasant sounding output. Because the unique microphone structure is combined with the electronic circuit the noise cancelling apparatus of the present invention provides a cleaner, more pleasant sounding output than that of the prior art.

Abstract: An apparatus for mounting a noise cancelling microphone (34) within a communication device comprises a housing having a front portion (36), a back portion and side portions (40). The front portion (36) and one of the side portions (40) have apertures (38 and 40). Within the housing lies a receptacle (32 or 50 or 100) for retaining a microphone or transducer (34). The receptacle is arranged and constructed to form a chamber (32) between the apertures (38 and 40) in the front portion (36) and the side portion (40) of the housing.

Abstract: A boundary-layer microphone may obtain a frequency independent, hemispherical directional characteristic with a high tonal quality. The geometrical configuration of the mounting plate and the installed location of the membrane within the surface of the mounting plate are chosen so that a flat frequency response is obtained at the installed location of the membrane, i.e., the superposition of the incident primary sound field on the secondary sound field created by diffraction will not cause any deviation from a flat frequency response and a smooth, hemispherical polar pattern. The mounting plate may be triangular. The membrane may be installed in the vicinity of the center of gravity of a scalene triangle.

Abstract: An apparatus for retracting a microphone is provided and consists of a microphone holder affixed to a free end of a retractable chain from a spool within a housing whereby when an operator needs to transmit, the microphone is pulled away from the housing. When transmission is completed the chain will go back into the housing around the spool place the microphone back against the housing where it is safe from damage and out of the way. Modifications of the spool is provided to allow for different lengths of chain to be wrapped around the spool.

Abstract: An audio equipment enclosure and methods for stacking audio equipment enclosures. One enclosure according to this invention has a compartment for enclosing and supporting an audio amplifier, a compartment for enclosing and supporting one or more audio effects devices, and a compartment for enclosing one or more speakers. A wheeled tray can be releasably secured to the bottom of the enclosure. An extending pedestal member projecting from the bottom of an enclosure can be received in a recess in the top of another enclosure or a recess in a wheeled tray. Front and rear lids or doors on an enclosure can provide access to various items in an enclosure and openings in the enclosures can provide a flow-through air path to enhance air circulation. A fan can be provided in an enclosure to further enhance air circulation and a remotely senseable microphone can be provided near each speaker.

Abstract: The invention comprises a microphone and loud speaker system in which the components include a cylinder having a center section and an end section at each end of the center section in axial alignment with one another. The adjacent ends of the center and end sections are elliptical and lie in planes oriented at an angle of 35.degree.16' to the longitudinal axis of the module, the long axes of the ellipses are oriented at 45.degree. to horizontal. The planes of the elliptical ends are substantially isomorphic to the tympanic membrane of the human hearing structure and represent half the dihedral angle of a regular tetrahedron. All of the loudspeaker transducers are shielded by sheilding cylinders with elliptical end faces lying in planes oriented, at half the dihedral angle of a regular tetrahedron, namely, 35.degree.16' to the axes of the cylinders, with the long axes of the ellipses oriented at 45.degree. to the horizontal.

Abstract: An acoustic damper for substantially reducing the reverberation echoes at the junction between an acoustic signal propagating fluid and a material having an acoustic impedance substantially different from that of the fluid. The damper, which is particularly adapted for use in ultrasonic transducers, is formed of a material having an acoustic impedance which substantially matches the acoustic impedance of the fluid, such material preferably being a foam plastic material having sufficient hardness to be acoustically stable. For preferred embodiments, the damper is formed of a laminate of the layer described above and a second layer of a material which provides high acoustic attenuation, such as cork material.

Abstract: A sound system, for a band or the like, incorporates an anechoic enclosure which allows a performer to use the same desired speaker color under all performing conditions and which insulates the audience and other pick-up microphones from each sound-source's speaker and insulates the pickup microphone for each sound source from the ambient room sounds. According to the system, a sound source, such as a musical instrument, outputs a first sound signal which is amplified and fed to a speaker in an anechoic enclosure. In response to the speaker output, a microphone in the anechoic chamber outputs a second sound signal which is amplified and distributed to room speakers. In its exemplary embodiment, the anechoic enclosure comprises four laminated layers: an inner layer of rigid closed-cell foam surrounding a chamber; a layer of denser flexible, closed-cell foam; a second layer of rigid closed-cell foam; and an outer hard, rigid layer. The enclosure may be opened so that the speaker therein may be heard.

Abstract: A hollow enclosure that suspends a bidirectional microphone element within, in such a fashion as to improve the unidirectional characteristics, of said bidirectional microphone.

Abstract: A sound-wave receiving applicance comprises a resonance panel and a crystal type piezoelectric microphone responsive to oscillations generated by the soundwaves, said microphone being adapted for connection to an amplifier. The crystal of the microphone is subjected, between two pole members, to a mechanical initial pressure to increase the pressure sensitivity of the microphone relative to the resonance panel. The receiving applicance preferably has means for manual adjustment of the initial pressure which is absorbed by the resonance panel via one pole member. The resonance panel of the receiving appliance preferably is made of a material, such as a cellular plastic, having a higher porosity and a lower specific gravity than ordinary wood.

Abstract: An electroacoustic device comprises an array of electroacoustic transducer elements for producing a prescribed directional response pattern at a first frequency. Each element includes apparatus for restricting the frequency range of sound waves incident on said element so that the directional response pattern is invariant over a prescribed frequency band.

Abstract: Acoustic frictional resistance comprises a plate having at least one laser-formed hole therethrough. The plate is formed by positioning a plate preferably one having a thickness smaller than one and one-half milimeters alongside a laser and directing the laser beam so that it cuts a hole through the plate. During the process of producing the resistance, the value of the acoustic friction is measured as a pressure drop of a constant air stream or as an expenditure of electrical energy for an electrically excited electroacoustic transducer. This measurement is then used as a variable or as a standard for controlling the process. Advantageously, a coherent beam is emitted by the laser which is deflected by mirror from a horizontal to a vertical direction and focused by means of a lens to work in a contact-free manner on a workpiece supported on a support member such as a movable table. By moving the table in two coordinate directions, a plurality of bores are formed in a pattern in a workpiece.

Abstract: An electroacoustic transducer has a front air chamber in front of the diaphragm that vibrates upon receiving sound waves or produces sound waves upon vibration and a back air chamber provided in the rear of the diaphragm. The electroacoustic transducer of the present invention further includes an auxiliary air chamber that is provided in the rear of the back air chamber that is coupled thereto by through holes. The auxiliary air chamber is divided into at least two smaller air chambers which are coupled to each other by a small orifice.

Abstract: A new voice tube assembly for post-auricle headsets is disclosed. In one aspect of the invention, first and second curved, rigid tubular sections are employed to connect a flexible main voice tube section with the top of a post-auricle capsule containing a microphone and a receiver. The curved, rigid tubing sections are rotatable to maximize positional flexibility. In a second aspect of the invention, a shaping wire is included throughout a substantial portion of the length of the main voice tube section. The shaping wire is employed in order to permit the use of thinner and lighter material for the main voice tube section, and to facilitate shaping of the main voice tube section to the geometry of the wearer's face and locating of the open end of the main voice tube section adjacent the wearer's mouth.

Abstract: A noise cancelling telephone transmitter comprising a cap and a cup coupled together so as to form an assembly insertable as a unit in the receptacle of a telephone handset. The cap is provided with an opening for passing sound. The inlet of the cap opening is covered by an acoustically deformable material such as a Mylar membrane. An electret microphone is mounted within the assembly such that the microphone acoustic entrance faces the outlet of the cap opening. A ring-shaped acoustic damping element is interposed between the cap underside and the plane of the microphone acoustic entrance. The cap is provided with a depending acoustic baffle which surrounds the damping element proximate the plane of the microphone acoustic entrance.

Abstract: A transducer rendered operative by a battery voltage source is mounted on and closely spaced from a sonic radiating surface by a sonic coupling body to which a housing is secured in enclosing relation to both the transducer and the battery source. Openings in the housing expose a volume control knob and an output signal jack through which a signal cable connects the transducer to a remotely located amplifier.

Abstract: A wireless hands-free conference telephone system includes an FM transmitter having multi-directional sound pick-up capability and battery power is adapted for remote wireless transmission of sounds originating in the area adjacent the transmitter to a unitary receiver, amplifier and voice switcher adapted for signal conducting connection to a conventional telephone system. The receiver portion of the unitary system is adapted for receiving the signal from the FM transmitter. The amplifier provides power to drive loudspeakers which radiate the sound incoming from the telephone system. A voice switching circuit is positioned between the telephone, the transmitter and the loudspeaker circuit, and is able to ascertain signal strength from the transmitter circuit and the incoming telephone line, discern which is the stronger signal, and increase the gain of that signal while decreasing the gain of the opposing signal.

Abstract: A modular transducer mounting arrangement includes a substantially planar support plate. An aperture having an angular bevel is provided in the support plate such that a loudspeaker may be positioned in the bevel to allow sound to exit from the loudspeaker in a manner which is substantially unobstructed acoustically. An adhesive shock absorbing pad is attached to the rear of the support plate for isolating the loudspeaker microphone and support plate from mechanical shock. This creates a free floating and reliable transducer mounting assembly which provides shock isolation and easy serviceability.

Abstract: A microphone hanger, which permits a microphone attached to it to be directed at various sound sources in a studio, auditorium, church or other environment, includes a cylindrical base having a disc-shaped top wall carrying a socket for a vertically depending microphone cable, and a disc-shaped bottom wall slidably received within said base for rotation about its longitudinal axis. The rotatable bottom wall carries a microphone mount for rotation with the bottom wall, and an opening is formed in the bottom wall to accommodate a cable extending from the socket to a microphone carried by the microphone mount.

Abstract: A pickup device for picking up sound generated by the vocal chords and transmitted through bones from the nasal bone. A microphone (11) is mounted on or embedded into an eyeglass-like assembly (13, 15). When the microphone is mounted as a nosepiece, it is made into direct contact with the nose so that it directly picks up vibration transmitted through the nasal bone. When the microphone is mounted on the eyeglass-like frame or embedded therein, it picks up vibration transmitted through the nosepieces and eyeglass-like frame. A cord (12) whose one end is electrically connected to the microphone is held by holding member extended from the eyeglass-like assembly (13, 15) so that the transmission of mechanical vibration to the microphone is prevented.

Abstract: A microphone unit for mounting in a protective headwear including a housing member for housing the microphone unit and a sound introducing passage forming an aperture in the housing member for introducing a sound pressure into the microphone unit. The sound introducing passage includes a configuration wherein an area of the aperture thereof increases as the distance increases away from a sound collecting surface of the microphone unit. A communication passage is formed in the housing member which provides communication between a surface of the microphone unit other than the sound collecting surface and the exterior of the housing member. The housing for the microphone unit is mounted at a position displaced a predetermined distance away from a central axis of said protective headwear. The microphone unit selectively receives audible sounds generated by a user of the protective headwear. Sound tubes are connected to the speaker case and positioned along an inner surface of the protective headwear.

Abstract: An audio pickup for musical instruments employing a condenser-type microphone mounted on a suction cup which is pressed against the sounding board or the like of the instrument.

Abstract: Anti-side tone transmitter insertable in a telephone handset improves transmission of the speaker's voice without distortion in high ambient noise environments. The transmitter cap is provided with a central opening in communication with an electret microphone. One or more satellite openings are spaced from and at least partially surround the central opening. An acoustic damping element is located below the satellite openings. The electret microphone is mounted below the cap on a PC board which contains the transmitter circuitry. The PC board is seated on a shelf formed in the interior surface of the side wall of the transmitter cup. Conventional telephone handset cord transmitter wires may be connected to screw terminals on the base of the transmitter cup or to spade lugs mounted on the PC board.

Abstract: Apparatus for connecting an electrical musical instrument to a public address system that includes a speaker having a cone-shaped diaphram, a mounting bar positioned across the mouth of the speaker and a microphone supported in the bar that passes into the cone to pick up the audio passing through the speaker and transmit the audio to a public address system.