Abstract: Caloric stimulation and pressure stimulation can be applied to the ear for treatment of neurological disorders, such as migraine, pain, and headache. Heat can be applied first to increase the sensitivity of the mechanoreceptors in the ear. The pressure can be applied after heating to produce a stronger neurological response than would occur without the heating. In some cases, cooling can be used. Valves can be used to direct fluid flow to a right ear, a left ear, or both. Valves can be used to transition the system between an irrigation or caloric mode and a pressure mode. Green eyewear can be used for therapeutic relief.

Abstract: A hollow cathode apparatus includes an outer tubular dielectric barrier circumferentially surrounding an outer tubular surface of the cathode tube, the outer tubular dielectric barrier being composed of a barrier material which is electrically non-conductive. Also disclosed is a system comprising the hollow cathode apparatus, an anode which is spaced from the output end of the tubular cathode, and electrical circuitry connected between the cathode tube and the anode for connection to a source of electrical power for providing an electrical potential between the cathode and anode to cause an electric current to pass from the emitter into the input gas to form a plasma which is then output through the output end of the cathode tube to form a plasma plume.

Abstract: The present disclosure may disclosure an electronic device having a water repellent structure. The disclosure electronic device may include: a housing; a speaker module disposed inside the housing and coupled to the outside of the electronic device; a sensing module disposed inside the housing and coupled to the outside of the electronic device; and a processor coupled to the sensing module and the speaker module. The processor may be configured to determine whether foreign matter is present via the sensing module, and output a signal of a specified frequency range via the speaker module so that at least part of the foreign matter moves to the outside, based on the sensing result.

Abstract: A speaker apparatus is provided in order to both receive and dissipate heat and to provide acoustic absorption for sound waves propagating through a speaker cavity. The speaker apparatus includes a speaker and a speaker cavity configured to receive sound waves emitted by the speaker for propagation through the speaker cavity. The speaker apparatus also includes a heat dissipation structure disposed at least partially within the speaker cavity. The heat dissipation structure includes a thermally conductive mesh that at least partially fills the speaker cavity. The heat dissipation structure further includes an active element configured to direct heat generated by a component into the thermally conductive mesh for dissipation therein. The thermally conductive mesh is configured to provide acoustic absorption for the sound waves propagating through the speaker cavity.

Abstract: A method of making a thermoacoustic device includes molding and cutting laminated sheets into half shell portions. Carbon nanotubes are adhered to a substrate having two electrical conducting portions thereon. Electrical conductors are applied to the conducting portions of the substrate. Tab sealant strips are applied around the perimeter of the substrate. Half shell portions are positioned on the top and bottom of the substrate with the electrical conductors extending therefrom. Heat is applied to seal the half shell portions together, suspending the substrate from the tab sealant strips. The method can further include providing a tube between the half shell portions prior to applying heat.

Abstract: A thermoacoustic device includes an outer shell having two half shells, each half shell having an outer flange and an inner region. The half shells are joined at the outer flanges such that the combined half shell inner regions define an inner cavity. A gas is provided within the outer shell inner cavity, and a substrate having electrodes is supported within the outer shell. A thermoacoustic element is mounted on the substrate in contact with the electrodes. Leads extend into the shell where they are joined to the electrodes. In further embodiments, the device is provided with a gas source and a regulator for controlling gas pressure in the inner cavity.

Abstract: An apparatus and system for generating sound and methods for making and using same. A motor-driving signal with an audio signal component is applied to a motor. When driven by the motor-driving signal, the motor thereby can generate a sound that corresponds to the audio signal component. An exemplary sound can include high-quality audio content such as music, speech, or a combination thereof. The motor-driving signal can be produced by modulating a carrier signal with the audio signal and can enable a vibration in the motor for generating the sound. When associated with a mobile platform, the motor can be configured to generate the sound and enable the mobile platform to move. Advantageously, without installing separate audio system hardware, the mobile platform thereby is capable of conveying information that is audible and comprehensible to a human. Communication efficiency between the human and the mobile platform can thus be improved.

Abstract: New exemplary heat exchange configurations that incorporate internal or external surfaces equipped with perturbators, for changing the thermal behavior of the system, or for modulating the surface temperature distribution of the flow surfaces. This is achieved by applying an acoustic wave to the fluid flow in a heat exchange passage, and selecting the frequency of the acoustic exciting wave to be the same as the acoustic resonance frequency of the heat exchange passage itself. As the traveling waves interact with the boundaries confining the heat exchange passages, constructive interference of the incident and reflected waves give rise to a standing wave. Thus, the heat exchange passages act as a resonator, and by superimposing this standing wave on the separating and reattaching fluid flow, significant heat transfer improvement can be achieved. This is accomplished without the need to significantly increase the pressure required to achieve the desired through flow.

Abstract: A loudspeaker includes a yoke, an annular magnet, a voice coil, and an open type inductive coil. The annular magnet is combined to the yoke, and a magnetic gap is provided between the annular magnet and the yoke. The voice coil is disposed in the magnetic gap. The open type inductive coil is combined to the yoke or the annular magnet, and the open type inductive coil corresponds to the voice coil. An inductive gap is located between the open type inductive coil an the voice coil, where the open type inductive coil includes a coil unit and two signal transmission lines. The coil unit includes opposite open ends, first ends of the signal transmission lines are respectively connected to the open ends, and second ends of the signal transmission lines are exposed out of the yoke and the annular magnet, so as to transmit mutual inductance signals between the coil unit and the voice coil to outside.

Abstract: An apparatus including a microphone; a speaker including at least one vibrating element and at least one movable section, where the at least one vibrating element is configured to at least partially move the at least one movable section to generate sound waves from the at least one movable section; and at least one vibration dampening member between the microphone and the at least one movable section, where the at least one vibration dampening member is suitably positioned in a path of vibration transmission between the at least one vibrating element and the microphone, where the at least one vibration dampening member is configured to absorb vibrations when the movable section is actuated by the at least one vibrating element.

Abstract: There is provided a boundary microphone inside which a unidirectional microphone unit is contained, the microphone including: a base plate; and a cover plate attached onto an upper face side thereof, wherein a thin and long tubular groove acting as an acoustic tube for making unidirectivity of the microphone unit a narrow directivity is formed on the base plate side, and therein, the microphone unit is contained. In order to prevent liquid from entering the tubular groove from the outside, between a peripheral edge part of the cover plate and the upper face of the base plate, a spacer that is composed of a water repellent thin film material and allows an inside of the tubular groove and outside air to communicate via acoustic resistance with a thin air layer is disposed so as to enclose an entire periphery of the tubular groove.

Abstract: A combined fan and loudspeaker element, comprising a motor driven rotor provided with wings or blades, wherein the wings or blades are adjustable in pitch resulting together with a rotation of the rotor in an air transport flow, said wings or blades having superimposed thereon a sound-pitch modulation corresponding to a desired sound-pitch with the rotation of the rotor.

Abstract: A rotary sound transducer having an improved output at higher frequencies. The invention includes stiff vanes that are preferably rigidly attached to a hub. A torsional actuator is provided in each vane. The torsional actuator selectively twists the tip portion of each vane. The torsional actuator for each vane is activated by an input energy source corresponding to the sound waves that are desired. The input force may also be electromechanical energy, purely mechanical energy, or some other form of energy.

Abstract: An electropneumatic horn assembly for generating sound may include a compressor unit, a compressor housing assembly, and a sound generating assembly. The compressor housing assembly may have a base portion and a movable cover portion, which may movably engage with the base portion to provide access to the compressor when in an open position and to provide a sealed bonding interface when in a closed position. The sound generating assembly may include a diaphragm and a horn duct housing. A plurality of vents may be embedded in the cover portion for venting air adjacent to an outer face of the compressor unit. A spacer may be positioned between an inner wall of the cover portion and an outer face of the compressor unit to provide an air channel therebetween. The cover portion and the base portion may comprise respective engagement means for securely affixing the cover portion to the base portion around the compressor unit to maintain operational stability of the horn assembly.

Abstract: An external ear canal pressure regulation device including a fluid flow generator and an earpiece having a first axial earpiece conduit fluidicly coupled to the fluid flow generator, whereby the earpiece has a compliant earpiece external surface configured to sealably engage an external ear canal as a barrier between an external ear canal pressure and an ambient pressure.

Abstract: A rotary reciprocating acoustic transducer for producing sound in response to an applied electrical signal has a ported tubular housing having a generally cylindrical chamber with an interior lumen which is generally symmetrical about a central axis and opposing first and second linear reciprocating electrodynamic motors mounted over the tubular housing member's first and second open end, with a reciprocating rotatable transducer vane assembly with first and second rotating vanes projecting radially away from a central, axially aligned shaft driven by the first and second linear reciprocating motors.

Abstract: Systems, apparatus, devices, and methods for converting electrical signals into sound using an acoustic transducer. The inventive acoustic transducer utilizes the motion of an airfoil shaped element to generate a sound wave, with the airfoil element being driven in response to an electrical signal input to a suitable driving element. In some embodiments, the airfoil element or elements act to mechanically couple the motion of an armature attached to the driver to the surrounding air, producing sound waves in a more efficient manner than typical acoustic transducer devices. Embodiments of the invention may be used in the design of loudspeakers, earpieces, headphones, and other devices for which a high efficiency transducer is desired.

Abstract: An external ear canal pressure regulation device including a fluid flow generator and an earpiece having a first axial earpiece conduit fluidicly coupled to the fluid flow generator, whereby the earpiece has a compliant earpiece external surface configured to sealably engage an external ear canal as a barrier between an external ear canal pressure and an ambient pressure.

Abstract: A speaker apparatus selects a path which emits a speaker sound. The speaker apparatus includes a speaker unit for outputting the sound generated from voice data, a body including at least one or more emission paths for guiding and emitting the sound output from the speaker unit, and a member for opening or shutting out at least one emission path.

Abstract: The disclosure provides a speaker-connector module and a handheld electronic device. The handheld electronic device includes a body and a speaker-connector module. The body has an opening. The speaker-connector module is assembled in the body and correspondingly disposed to the opening. The speaker-connector module includes a housing, a speaker and an electrical connector. The housing has a major sound passage, wherein the major sound passage has a major input end and a major output end. The speaker is assembled in the housing and has a sound outlet surface, wherein the major input end is communicated with the sound outlet surface. The electrical connector is disposed in the major sound passage and adjacent to the speaker, and the major input end is connected to the electrical connector.

Abstract: Systems, apparatus, devices, and methods for converting electrical signals into sound using an acoustic transducer. The inventive acoustic transducer utilizes the motion of an airfoil shaped element to generate a sound wave, with the airfoil element being driven in response to an electrical signal input to a suitable driving element. In some embodiments, the airfoil element or elements act to mechanically couple the motion of an armature attached to the driver to the surrounding air, producing sound waves in a more efficient manner than typical acoustic transducer devices. Embodiments of the invention may be used in the design of loudspeakers, earpieces, headphones, and other devices for which a high efficiency transducer is desired.

Abstract: A duct design and methods for designing ducts are described herein. The duct has a profile described by an equation that balances momentum of the fluid flowing through the duct with an adverse pressure gradient. The duct profile is configured to: (i) maintain the fluid's momentum to be greater than the adverse pressure gradient present at any location within the duct, such that no boundary layer separation occurs; and (ii) achieve a fluid exit momentum of approximately zero.

Abstract: Systems and methods for a high performance transducer are disclosed. For example, one described transducer includes: a pressure locking chamber with at least one orifice; a two-state solenoid configured to be controlled by a control circuit and a capacitor, the two-state solenoid comprising a solenoid housing; and a permanent magnet assembly configured to be actuated by the two-state solenoid to move between an open and a closed position, the permanent magnet assembly comprising a stopper configured to seal the at least one orifice in the closed position.

Abstract: A diaphonic valve utilizing the principle of the Synthetic Jet is disclosed herein. A diaphonic valve pump is provided for the inflation of an in-ear balloon. More complex embodiments of the present invention include stacks of multiple synthetic jets generating orifices as well as an oscillating, thin polymer membrane. In one or more embodiments of the present invention, a novel application is provided for the creation of static pressure to inflate or to deflate an inflatable member (balloon). In addition, sound can be utilized to inflate or deflate an inflatable member in a person's ear for the purpose of listening to sound.

Abstract: The present invention relates to an apparatus for controlling the movement of a cone paper used for outputting sound, and a flexible OLED covered on the cone paper in order to enhance the sound quality of a visual speaker. In a visual speaker which includes a voice coil, a magnet, an edge, a unit enclosure, a flexible OLED for displaying video images, and a speaker cone paper, a visual speaker is characterized in that a speaker cone paper configured to output sound, a flexible OLED covered on the speaker cone paper, an edge, and a unit enclosure are formed in an integral airtight structure filled with a compressed gas, and a compression piston and a compressed gas adjusting device are further disposed for adjusting the pressure of the inner compressed gas, so that it is possible to control the movements of the flexible OLED and the speaker cone paper.

Abstract: A high-frequency pneumatic loudspeaker for sound broadcasting is provided, and comprises a housing, silencer exhaust holes, air inlet port, supporting plate, throat canal, central cone, annular nozzle, obstructing ring, and a voice coil and leads. Lower and an upper press plates hold the obstructing ring and the voice coil in position, a magnet having inner and outer magnetic poles is connected therewith, wherein a small gap exists between the obstructing ring and the end of the annular nozzle. This provides the advantages of both air passage area modulation by a sleeve air valve and airstream direction modulation by jet obstruction, reduces airstream consumption, improves air-sound conversion efficiency, and improves structures of an annular air flow-splitter, voice coil and leads. A cooling system is provided to improve high-frequency modulation sensitivity, operation stability, and/or extended fault-free operation time.

Abstract: A speaker apparatus includes a speaker and a sound box. The sound box is shaped like a wine barrel and includes arced side boards and parallel top and bottom boards coupled to upper and lower ends of the side boards, respectively. The sound box is divided by at least an isolating board into air chambers interconnected with one another via at least an air aperture formed in the isolating board, and at least an air venting hole is formed through at least one of the side boards so as to communicate the air chambers with the outside. The speaker is installed on the top board via an installation hole formed therein. The interconnected air chambers and side boards produce air cushions corresponding to resonant frequency sections of the speaker, thereby enabling the speaker to reproduce original audio sounds without interfering with a successively formed air cushion.

Abstract: Silicon and glass micromachined (MEMS) acoustic sensors incorporating trapped-liquid architectures are disclosed. The trapped liquid serves as an acoustic transmission medium allowing the input port to the system to be physically separated from the sensing location. The trapped liquid interacts with a conductive, flexible sensing membrane. Sound pressure waves enter the trapped liquid through an input membrane, travel to the sensing membrane, and excite vibrations of the sensing membrane. The vibrations of the sensing membrane are measured using on-chip capacitive sensing. The capacitive sensing structure is formed by the conductive sensing membrane and a fixed conducting top electrode. As the gap between the conductive sensing membrane and the fixed top electrode varies, the capacitance varies, leading to an electrical signal which is the electrical output of the system.

Abstract: A loudspeaker arrangement (10, 100) is operable to convert in operation an electrical drive signal to acoustic radiation. The loudspeaker arrangement (10, 100) includes a panel (20) including one or more groups of one or more apertures (60) therein, and at least one component (30) cooperating with the panel (20) to define an inner volume (80) coupled in fluidic communication with an external region (90) to the loudspeaker arrangement (10), 100) via the one or more groups of one or more apertures (60). The panel (20) has mounted thereon at least one exciter element (50) for operably causing the panel (20) to flex for generating acoustic radiation from the loudspeaker arrangement (10, 100).

Abstract: An electronic apparatus having a structure in which the inside of a cabinet having a speaker unit incorporated therein is effectively cooled, so that the speaker unit satisfactorily plays back a bass sound in which the speaker cabinet has at least two bass-reflex ducts. One bass-reflex duct is used for air-discharge, through which air in the cabinet is discharged by a fan unit, and another bass-reflex duct is used for air-intake. Thus, the inside of the speaker cabinet is effectively cooled while making use of the bass-reflex effect.

Abstract: A method of converting an audio signal into vibratory modulation of a fluid includes converting a series of pulses representative of the audio signal into a plurality of signals having an intermediate peak-to-peak voltage; summing said signals having said intermediate voltage to provide a driver signal having a high peak-to-peak voltage; supplying said driver signal to an electrostatic fluid accelerator; and generating a corona discharge inducing said vibratory modulation of said fluid.

Abstract: A high-frequency pneumatic loudspeaker for sound broadcasting is provided, and comprises a housing, silencer exhaust holes, air inlet port, supporting plate, throat canal, central cone, annular nozzle, obstructing ring, and a voice coil and leads. Lower and an upper press plates hold the obstructing ring and the voice coil in position, a magnet having inner and outer magnetic poles is connected therewith, wherein a small gap exists between the obstructing ring and the end of the annular nozzle. This provides the advantages of both air passage area modulation by a sleeve air valve and airstream direction modulation by jet obstruction, reduces airstream consumption, improves air-sound conversion efficiency, and improves structures of an annular air flow-splitter, voice coil and leads. A cooling system is provided to improve high-frequency modulation sensitivity, operation stability, and/or extended fault-free operation time.

Abstract: A speaker apparatus includes a speaker, and a circuit to operate the speaker. The speaker apparatus further includes a speaker box having an opening to enclose a back of the speaker; a casing accommodating the speaker box combined with the speaker and the circuit therein, and communicating with an outside so as to dissipate heat from the circuit; and a duct penetrating the casing and the speaker box so as to emit back sound of the speaker. The present invention provides a speaker apparatus, which has high heat-dissipating efficiency, can be manufactured in various designs, and prevents a user from being burned.

Abstract: In combination with a loudspeaker assembly that includes a speaker diaphragm that is displaced to produce sound, the combination comprising a spinner element mounted to rotate in the path of sound waves produced by the speaker diaphragm; and a rotary drive for rotating the spinner, the spinner defining sound wave passing through openings, in said path.

Abstract: A loudspeaker assembly includes a speaker diaphragm that is displaced to produce sound, and a spinner element mounted to rotate in the path of sound waves produced by the speaker diaphragm, the spinner defining sound wave passing through openings, in said path. Illumination of interior structure, may be provided, for visual effect through openings defined between rotating spinner arms, and between non-rotating grille arms. Different combinations of grilles and spinners are easily enabled by mounting structure.

Abstract: A loudspeaker system has a diaphragm for producing sound, a loudspeaker driver mechanism operable for moving the diaphragm in response to an applied electrical signal from an audio signal source, a blower positioned for directing air under pressure over the loudspeaker driver mechanism so that heat generated by the loudspeaker driver mechanism can be convectively removed, and a control circuit electrically connected to the blower and adapted for connection to the audio signal source such that an increase in the applied electrical signal causes a corresponding increase in speed of the blower. The control circuit includes a power limiting device and a switching device that is connected in parallel with the power limiting device. The switching device is actuable from a normally closed state to an open state when the applied electrical signal is above a predetermined level to regulate the speed of the blower.

Abstract: Sound signals are detected. Light signals are generated that pass through a membrane of a bubble within a trench. The sound signals cause deformations within the membrane of the bubble. The light signals are detected after the light signals have passed through the membrane. The sound signals are reconstructed from the light signals detected by the optical detector.

Abstract: A rotor having a yoke is rotatably supported in a frame, and a stator provided in the frame at a central portion of the frame. An annular first permanent magnet is provided on the yoke, and an annular second permanent magnet is provided on the yoke. A diaphragm is supported in the frame, and a voice coil is secured to the diaphragm and inserted in a gap formed by the first permanent magnet. At least two coils are provided on the stator for forming magnetic fluxes between the rotor and the stator so as to rotate the rotor.

Abstract: A pressure transducer which has a closed chamber which is full of oil or other non-compressible liquid. Pressure communicates with a diaphragm which defines one side of the closed chamber and the pressure communicates via the oil with a pressure sensor which is mounted within the oil spaced from the diaphragm. The liquid entered the closed chamber through a inlet hole with a selected volume driven into the closed chamber by a ball which is forcefully driven a selected distance into the inlet hole before stopping at the end of the inlet hole against a physical stop.

Abstract: This invention presents a novel means to passively achieve a compact moving-coil actuator with a very low natural frequency. The diaphragm and voice coil are mounted in a sealed enclosure from which the air is partially or completely evacuated. This reduces the air spring effect. The diaphragm is supported by a non-linear, buckling, or collapsible support apparatus. By taking advantage of the non-linear stiffness properties of such structures, the stiffness of the actuator can be designed to be small at the operating point, which when combined with the moving mass, yields a low natural frequency.

Abstract: Disclosed herein is a two-way speaker for mobile phones. The two-way speaker for mobile phones includes a frame having a hollow interior and a sound output hole formed on a wall of the frame. A magnet is mounted in the hollow interior of the frame and has a first through hole communicating with the sound output hole. A top plate is mounted on the magnet and has a second through hole communicating with the first through hole of the magnet. A diaphragm having a wave form is attached to the front of the frame, and a voice coil is attached to the back surface of the diaphragm at a position adjacent to the magnet. The communicating first and second through holes and the sound output hole form an air passage ensuring a smooth circulation of air when the diaphragm is vibrated, thus accomplishing desired frequency characteristics of a receiver.

Abstract: An audio system for portable computers utilizes spaces typically dedicated, at least in part, to cooling the system. An embodiment is shown in which a speaker is installed at the intake of a centrifugal blower and directs sound through the incoming air. A housing is built to channel the intake air, as well as the outgoing air, over a CPU and across a heat sink.

Abstract: A loudspeaker (81) comprising an enclosure, an acoustic radiator (2) in the enclosure, a compliant suspension (3) mounting the radiator in the enclosure for pistonic movement relative thereto, and transducer means (9) for driving the radiator pistonically, characterized in that the radiator is a panel-form distributed mode acoustic radiator, by a first transducer mounted wholly and exclusively on the radiator to vibrate the radiator to cause it to resonate, and by means (11) for varying the air pressure in the enclosure to cause the radiator to move pistonically.

Abstract: Apparatus (21) is described for reproducing low frequency sound in response to an applied electrical signal having a rotary acoustic radiator (22) comprised of a chamber (26) having a rotor assembly (58) including a shaft (61) and movable vanes (71, 72) secured to the shaft rotatably mounted in chamber for rotation on a longitudinal axis. Stationary vanes (62, 63) are mounted in the chamber and extend generally radially between the chamber walls and the shaft. The chamber has ports (64, 66, 67, 68) therein opening into the chamber and disposed adjacent the stationary vanes on opposite sides of said stationary vanes. The movable vanes are disposed on opposite sides of the stationary vanes and extend generally radially between the chamber walls and the shaft.

Abstract: An acoustic resonator includes a chamber which contains a fluid. The chamber has a geometry which produces self-destructive interference of at least one harmonic in the fluid to avoid shock wave formation at finite acoustic pressure amplitudes. The chamber can have reflective terminations at each end or a reflective termination at only one end. A driver mechanically oscillates the chamber at a frequency of a selected resonant mode of the chamber. The driver may be a moving piston coupled to an open end of the chamber, an electromagnetic shaker or an electromagnetic driver.

Abstract: An elliptically shaped flow modulator in a duct with a circular cross section is used to produce a time varying head loss in a steady fluid flow in the duct, which results in an unsteady volume velocity at the end of the duct which radiates an acoustic field; the flow modulator can be used in place of a conventional acoustic source in an active noise control system.

Abstract: A loudspeaker, comprising a magnet unit which generates a magnetic field and a movable element suspended for resilient movement around a stable rest position for radiating sound with selected properties. The loudspeaker further comprises an electrical conductor connected to the movable element and having current feed terminals. The conductor is placed in the magnetic field such that when current is passed through the conductor a force is exerted on the movable element so that the movable element is displaced from its rest position. The loudspeaker includes a cooling element producing a gas flow for forced cooling of the conductor.

Abstract: Apparatus for reproducing low frequency sound in response to an applied audio signal having a rotary acoustic radiator comprised of an enclosure having a cylindrical sidewall and end walls adjoining the sidewall and forming a cylindrical chamber. A rotor assembly including a hub and movable vanes secured to the hub is rotatably mounted in the chamber for rotation on a longitudinal axis. Stationary vanes are mounted in the chamber and extend between the cylindrical sidewall and the hub and extend between the end walls. The enclosure has ports therein opening into the chamber and disposed adjacent the stationary vanes on opposite sides of said stationary vanes. The movable vanes are disposed on opposite sides of the stationary vanes and extend between the cylindrical sidewall and the hub and between the end walls.

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: Low frequency, high intensity sound is produced using a conduit having a flow of high velocity and low pressure air. A pair of sound ports are provided in the conduit, and a rotary valve connected to a reversible servomotor and audio source is employed to direct the flow of air toward and away from the ports.