Abstract: A system (200) and method (400) for near-end detection of voice (107) in speakerphone mode is provided. The method can include determining (402) a convergence of an adaptive filter (220), determining (404) a dissimilarity between an autocorrelation (311) of an echo estimate (244) and an autocorrelation (312) of a microphone signal (243) if the adaptive filter has converged, computing (406) a weighting factor (279) based on the dissimilarity, applying the weighting factor to a voice activity level (281) to produce a weighted voice activity level (283), comparing (410) the weighted voice activity level to a constant threshold, and performing (412) a muting operation in accordance with the comparing for providing half-duplex communication.

Abstract: The invention relates to an improved electro-dynamic loudspeaker.

Abstract: This invention is an audio system capable of identifying frequencies of feedback signals and filters these feedback signals. Frequency interpolation is utilized on a sampled frequency spectrum signal corresponding to a feedback signal, where the frequency interpolation allows the frequency of the feedback signal to be identified, especially where the frequency lies between samples of the frequency spectrum signal. The frequency identification allows a less intrusive filter, such as a notch filter, to be placed at the determined frequency of the feedback to eliminate the feedback signal. The placement of the notch filter reduces the effect on the audio signal provided by the audio system. The audio system may provide adaptive filtering of multiple feedback signals, using a single filter such as a notch filter.

Abstract: An apparatus and method for controlling a plurality of speakers, comprising an amplifier for amplifying and outputting a play signal to be played over the speakers; and at least one sensor disposed proximal to at least one of the speakers for sensing at least one environmental condition and outputting sensing data to a controller, wherein the controller adjusts the play signal to compensate for environmental changes based on the sensing data.

Abstract: The invention relates to a method for reducing feedback caused by electromagnetic interference between an induction coil and an output transducer, a voltage supply or an amplifier or a combination thereof, the method comprising: producing by means of a filter an equivalent of an electromagnetic feedback path in a system with a pickup coil and subtraction of the equivalent of the feedback signal from the input signal in order to obtain feedback reduction. The invention further relates to a device for implementing the method, the device comprising an induction coil and an output transducer, voltage supply or an amplifier or a combination thereof. The device further comprises filter means for generating an equivalent of an electromagnetic feedgack signal occurring between the induction coil and an output transducer, a voltage supply or an amplifier or a combination thereof and means for subtracting the equivalent from an input signal in order to obtain feedback reduction.

Abstract: A speaker apparatus includes a speaker unit, a passive radiator unit, and a front baffle on which the speaker unit and the passive radiator unit are mounted to form a portion of a speaker box and a back plate. A closed front chamber is formed by the front baffle for coupling the sound output generated from the back of the speaker unit with the passive radiator unit. A closed rear chamber is formed by the front baffle and the back plate for confining sound output generated from the front of the speaker unit. The speaker unit is disposed in a direction opposite to the direction of passive radiator unit, or in a direction approximately opposite.

Abstract: A loudspeaker device comprising a power amplifier (13) to which an input signal is delivered via a subtracter (6), a speaker unit (1) for reproducing output signals delivered from the power amplifier (13), an acoustic pipe (2) coupled in front of the speaker unit for guiding the sound waves, a microphone (4) for detecting an acoustic outputs radiated from the speaker unit, a microphone amplifier (5) for amplifying an acoustic output signals detected by the microphone, and a negative feedback circuit. Output signals of the microphone amplifier are delivered to the subtracter, at the same time the same output signal is connected to a high-pass filter (7) to be delivered to the subtracter. Thus the negative feedback circuit is formed to suppress peaks and dips for providing a flattened sound pressure frequency characteristic.

Abstract: The present invention provides a feedback-controlled audio system. A single internal pressure-sensitive detector is used as the sensor. The primary radiator is mounted facing inward to minimize acoustical delay from the speaker. The present invention also provides a method for increasing acoustical accuracy using such an audio system.

Abstract: A thermal overload and resonant motion control circuit is provided for an audio speaker, the circuit generating a feedback signal to control the input applied to the speaker, which feedback signal is dependent on both the drive current to the speaker and the speaker impedance. More specifically, the feedback signal has a voltage which is substantially equally to the absolute value of K(bv?ai)H(s); where, K=a gain for the circuit, i=current of drive signal applied to the speaker, v=voltages of drive signal, a=percentage of drive current (i) sensed by the control circuit; b=percentage of drive voltage (v) sensed by the control circuit, H(s)=a lowpass filter transfer function for a lowpass filter of the control circuit, and s=a complex frequency variable.

Abstract: A sound signal reproducing apparatus for supplying sound signals of a plurality of channels to speakers via sound amplifier circuits includes: a power supply voltage controller for controlling a power supply voltage to the sound amplifier circuits; a plurality of filter circuits for passing predetermined frequencies of the output signal of each of the sound amplifier circuits in the plurality of channels; a plurality of level detection circuits for detecting levels of output signals of the plurality of filter circuits; an adder circuit for adding output signals of the plurality of level detection circuits; and a comparator circuit for comparing an output signal of the adder circuit with a reference level, so that an output signal of the comparator circuit controls the power supply voltage controller.

Abstract: A system for transducer compensation based on ambient conditions includes a transducer, a signal processor and an ambient condition sensor. The signal processor may process audio signals for the transducer. In addition, the signal processor may receive signals from the ambient condition sensor. The signals may represent ambient conditions being experienced by the transducer. The signal processor may dynamically adjust the equalization of the audio signals based on the ambient conditions to optimize operation of the transducer.

Abstract: It is known to make the performance of a loudspeaker “environment adaptive” in controlling a filter unit based on a measurement of the velocity/acceleration of the loudspeaker diaphragm and the associated sound pressure in front of the diaphragm, by means of an accelerometer and a microphone, respectively, thereby determining the radiation resistance of the diaphragm. The two sensors have to exhibit a constant transfer function throughout the life time of the loudspeaker, which make them very expensive. With the invention it has been found that the accelerometer can be replaced by another microphone held in a small distance from the diaphragm, and this conditions the possibility of using the same microphone for both measurements, e.g. simply by physically moving the microphone from one position to another. It will then no longer be required to use long-time stable sensors, whereby the price of the sensor equipment can be reduced dramatically. Also alternative arrangements are disclosed.

Abstract: A speaker apparatus in which a reproduced sound from a speaker unit is detected by a microphone and the reproduced sound from the speaker unit is corrected based on the detected signal. The speaker apparatus includes the speaker unit for reproducing an output signal from an amplifier, the microphone for detecting an acoustic output from the speaker unit, and a feedback circuit for feeding the detected acoustic output signal back to the input side of the amplifier. By placing the microphone near a position where sound pressure of at least one of a second and higher pipe resonance of an acoustic pipe is at minimum, an influence of the second and higher pipe resonance is reduced. As the influence of the second and higher pipe resonance is removed from the feedback circuit, stability of the feedback circuit is improved, and therefore, an acoustic characteristic of the speaker apparatus is improved.

Abstract: An anti-oscillation loudspeaker device where a reproduced sound is compensated based on a acoustic signal detected by a microphone and a reproduced band is enlarged is provided. In this loudspeaker device, a microphone is placed near a position where sound pressure of resonance occurring in a closed space for at least one of height, width, and depth of the inside of a cabinet is minimum. An influence of the resonance is restrained, a feedback circuit becomes stable, and a feedback amount increases.

Abstract: A method and system for providing a mixed-mode (current- and voltage-source) audio amplifier is disclosed. The mixed-mode amplifier includes a voltage sensing feedback path including a first network comprising at least one circuit; and a current sensing feedback path including a second network comprising at least one circuit. According to the method and system disclosed herein, the first and second networks vary an output impedance or transconductance of the amplifier as a function of frequency of the input voltage signal, such that at a first frequency range, the amplifier operates substantially as a current amplifier, and at a second frequency range, the amplifier operates substantially as a voltage amplifier, thereby inheriting distortion reduction of the current amplifier and stability of the voltage amplifier.

Abstract: A motional feedback (MFB) signal control unit includes a vibration displacement calculating part which generates a vibration displacement detecting signal in response to the input of a vibration detecting signal from a vibration detecting coil of a speaker unit, a vibration speed calculating part which generates a vibration speed detecting signal in response to the input of the vibration detecting signal, a processed signal generating part which generates a feedback signal in response to the input of the vibration displacement signal and the vibration speed detecting signal, and an adder which adds the feedback signal to a sound signal outputted from a sound reproducing unit so as to input the sound signal to a driving voice coil of the speaker unit.

Abstract: A method and system for using an audio transducer as both an input device and an output device is disclosed. The method and system include digitally modulating a primary input signal for driving the transducer as an output device, sampling an output signal generated from the transducer during off times of the modulated signal, and determining an input signal from the sampled output signal.

Abstract: A speaker system having intelligence for communication with the amplifier. The speaker system contains a communications module that transmits information across the connection between the speaker system and the amplifier with regard to the speaker characteristics. The communications module may be powered by a rectifier that derives power from a high frequency carrier signal passed to it by a high-pass filter. The method of operating the speaker generates a carrier signal and powers the communications module using the carrier signal. The communications module transmits information to the amplifier so long as the carrier signal is present and shuts down when the carrier signal is no longer present. An optional step includes allowing communication to the speaker system from the amplifier.

Abstract: A device for operating voice-controlled systems, such as communication and/or intercommunication systems in motor vehicles, includes a plurality of microphones and at least one loudspeaker. Voice signals received by the microphones are transmitted to the at least one loudspeaker. The voice signals are subjected to a low-value frequency shift before being transmitted to the loudspeaker(s) or to the input of a voice-controlled device to thereby suppress feedback.

Abstract: A pole piece 19 of a speaker main unit 1 has a pole 19a engaged with a bobbin 14 from the back side of a diaphragm 12, and a flange 19b horizontally expanding from the base of the pole 19a. In the pole 19a is formed a through hole 19c passing therethrough in an axial direction thereof, and in the bottom end of the through hole 19c is provided with a taper 19d which widens with it goes downward. A thin film piezoelectric element 4 is provided such that the element covers an external opening 19e of the through hole 19c, and one end 4a of a thin film piezoelectric element 4 is adhered to the bottom surface of the flange 19b.

Abstract: The active HVAC duct element can be inserted into a HVAC duct for attenuation of noise. The element works with an acoustical series arrangement of a passive acoustical component and an active acoustical component.

Abstract: An integrated individual listening device and decoder for receiving an audio signal including a decoder for decoding the audio signal by separating the audio signal into a voice signal and a background signal, a first end-user adjustable amplifier coupled to the voice signal and amplifying the voice signal; a second end-user adjustable amplifier coupled to the background signal and amplifying the background signal; a summing amplifier coupled to outputs of said first and second end-user adjustable amplifiers and outputting a total audio signal, said total signal being coupled to an individual listening device.

Abstract: An audio apparatus is constructed for use in negative drive of a loudspeaker having an internal impedance to perform a desired amplitude-frequency characteristic. In the audio apparatus, an amplifier device drives the loudspeaker with a driving voltage. A feedback device performs a positive feedback of a signal corresponding to the driving voltage of the loudspeaker to the amplifier device with a variable feedback gain, thereby causing the amplifier device to generate a negative impedance effective to negate the internal impedance of the loudspeaker. An adjustment device decreases the variable feedback gain of the feedback device as a level of the driving voltage of the loudspeaker increases, thereby adjusting the amplitude-frequency characteristic of the amplifier device.

Abstract: In a sound reproducing apparatus, a target control value is determined automatically from a noise and a sound radiated from a loudspeaker unit, and a volume of a reproduced sound is naturally compensated according to an amount of the noise against a masking due to a noise at a listening point. A first microphone is located near a loudspeaker box, and a second microphone is located in the loudspeaker box. A gain of s variable gain amplifier is changed so that an integrated value of a signal obtained by filtering and adding the outputs of the microphone may be equal to an integrated value of the filtered signal of the output of the variable gain amplifier.

Abstract: A method of limiting the power applied to a loudspeaker is disclosed, in which both the voltage and current applied to the loudspeaker are measured, and instantaneous power is directly calculated and used to control the level of the input signal that drives the amplifier powering the loudspeaker. When the power applied to the loudspeaker exceeds a prescribed threshold, the input level to the power amplifier is reduced until the measured power falls below the threshold. Also disclosed is a method for indirectly determining the voice coil temperature from the loudspeaker's voltage and current and reducing power to the loudspeaker when the temperature exceeds a prescribed threshold. The power level is actively controlled to prevent damage to the loudspeaker and to minimize audibly objectionable artifacts.

Abstract: The presence or absence of a speaker connected to an output terminal of an audio system is determined based on the electro-generator properties of the speaker. The audio system includes an output amplifier coupled to the output terminal. The method includes driving the output amplifier with a predetermined drive signal sufficient to produce a predetermined speaker excursion if a speaker is connected to the output terminal. The output amplifier is then isolated from the output terminal. A signal at the output terminal is sensed after the output amplifier is isolated. The sensed signal is compared with a predetermined reference for determining whether a speaker back-EMF is present. A speaker detection signal is generated indicating absence of a speaker if the back-EMF is not present.

Abstract: The present invention concerns an amplifier circuit comprising a signal input connection, a power amplifier which amplifies a signal coupled in by way of the signal input connection, a passive frequency divider which divides the signal amplified by the power amplifier into at least two channels, and at least two electroacoustic transducers or at least two output connections for electroacoustic transducers which are each connected to a respective channel made available by the frequency divider. In order to provide an amplifier circuit which manages with only one amplifier upstream of the passive frequency divider, which as far as possible includes no further active components and which nonetheless permits a balanced sound image from the loudspeaker which does justice to even the highest of demands, it is proposed in accordance with the invention that a passive negative feedback is provided between at least one output of the frequency divider and the input of the power amplifier.

Abstract: The present invention is directed to a speaker system that more accurately reproduces audio sounds by minimizing the negative effects from sound reflecting from a nearby wall. The invention is embodied in both methods and apparatus of differing forms. In one embodiment, the invention comprises a method that receives an electrical signal embodying an audio signal to be communicated to the speaker, and modifies the electrical signal by a measure that is based upon a separation distance separating the speaker and a wall. In another embodiment, the invention comprises a driver circuit for a an audio amplifier that, in turn, drives a speaker. The driver circuit includes a receiver configured to receive an electrical signal embodying an audio signal to be communicated to the speaker, and a signal modifying circuit configured to modify the electrical signal by a measure that is based upon a separation distance separating the speaker and a wall.

Abstract: An acoustic signal is input to a first voice coil of a speaker unit. A vibration information detecting unit comprised of a vibrational displacement detecting unit, a vibrational velocity detecting unit, a vibrational acceleration detecting unit, amplifiers, and an adder adds a signal indicating the vibrational displacement x, a signal indicating the vibrational velocity v and a signal indicating the vibrational acceleration &agr;. A power amplifier inputs the sum signal to a second voice coil of the speaker unit using a positive feedback or negative feedback.

Abstract: The sound absorber is a combination of an acoustical transformer with an actively simulated acoustical impedance. The acoustical transformer transforms the high active impedance into a low impedance at the mouth of the transformer. The absorber is tuned by changing the active impedance.

Abstract: A programmable speaker uses characterization data stored within the memory of the speaker and digital signal processing (DSP) to digitally perform transform functions on input audio signals to compensate for speaker related distortion and listening environment distortion. In a manufacturing environment, a non-intrusive system and method for tuning the speaker is performed by applying a reference signal and a control signal to the input of the programmable speaker. A microphone detects an audible signal corresponding to the input reference signal at the output of the speaker and feeds it back to a tester which analyzes the frequency response of the speaker by comparing the input reference signal to the audible output signal from the speaker. Depending on the results of the comparison, the tester provides to the speaker an updated digital control signal with new characterization data which is then stored in the speaker memory and used to again perform transform functions on the input reference signal.

Abstract: In a feedback compensation method and a feedback compensator in an acoustic amplification system such as a hearing aid, an adaptive feedback compensation filter generates a compensation signal from the amplified output signal, and one or more filters restrict the frequency range in which the compensation signal is generated. These filters are adaptable with regard to their filter function during the operation of the feedback compensator. The adaptation ensues with an analysis and control unit that checks the frequency range affected by the feedback and adapts the filter functions of the filters to it. The checking ensues, for example, by a comparison of the filter function of the feedback compensation filter with the filter functions of the filters to restrict the frequency range, or with the use of an oscillation detector.

Abstract: An automatic gain control circuit for use with a motorcycle radio and headset features an adjustable control for setting the maximum signal allowed to reach the headset, while allowing normal signal levels below that point to be controlled at the motorcycle radio. The circuit may be easily incorporated for use with a previously installed radio as well as an enhancement for new radio designs. Isolation transformers on both the input and output of the circuit eliminate the necessity to ground the circuit. Bass boost and internal gain circuits compensate for internal losses and headphone loading characteristics to provide near-transparent signal transfer below the set maximum signal level.

Abstract: Systems, devices, and methods are provided to inhibit at least one feedback component of an input audio signal by adjusting a feedback-inhibiting filter through a narrowband subaudible signal. The level of the signal may be determined using an audibility model so as to yield its subaudible quality.

Abstract: In a sound reproducing apparatus, a target control value is determined automatically from a noise and a sound radiated from a loudspeaker unit, and a volume of a reproduced sound is naturally compensated according to an amount of the noise against a masking due to a noise at a listening point. A first microphone is located near a loudspeaker box, and a second microphone is located in the loudspeaker box. A gain of s variable gain amplifier is changed so that an integrated value of a signal obtained by filtering and adding the outputs of the microphone may be equal to an integrated value of the filtered signal of the output of the variable gain amplifier.

Abstract: An apparatus for driving a speaker that includes an audio element moved by drive signals applied to the speaker, the speaker having a resistance and a force factor, includes: (a) an amplifier generating drive signals and having an output coupled with the speaker and an input; and (b) a feedback circuit coupling the speaker with the input and including: (1) a monitor coupled with the speaker and generating indicating signals representing selected speaker signal parameters; and (2) a processor coupled with the monitor, with the input and with a signal source providing received signals. The processor combines the received signals with the indicating signals to generate a modified signal for use by the amplifier in generating drive signals. The modified signal includes at least one factor relating to velocity of the audio element. Efficiency of the speaker is improved by inversely varying the resistance and the force factor with respect to each other.

Abstract: A method and corresponding apparatus for controlling the performance of a loudspeaker in a room includes the steps of, in a first acoustic environment, which may be regarded as a reference, determining the acceleration, velocity or displacement of the loudspeaker diaphragm and the sound pressure in front of the diaphragm, and, based on these quantities, determining the radiation resistance, radiated acoustic power or real part of the acoustic wave impedance. Thereafter, the above step is repeated in a second acoustic environment, which will normally be the actual listening room in which the loudspeaker is to be used.

Abstract: A control loop for sensing the fluctuation of the source voltage (V0) of a power amplifier (3) to feed it back to a switching regulator (5) is provided as well as a control loop to feed it forward to the switching regulator (5) by using PWM signal serving as the source for drive control of the power amplifier (3). The combination of feedback control and feedforward control more improves the precision of control than by just feedback control and results in an effective suppression of the fluctuation of the source voltage. The control can be carried out more simply than by the correction of the fluctuation of the source voltage through digital operation.

Abstract: A test signal generator (10) outputs a test signal which is obtained by cutting off a high-frequency component from a white noise signal. A signal switching device (18) selectively outputs either one of a positive-phase signal of the test signal and a negative-phase signal of the test signal, in response to a switching operation of the user. A selector (16) selectively outputs either one of the test signal and a musical sound signal to speaker terminals (26, 28). The test signal is reproduced while the selector (16) is connected to the test signal side. At this time, the test signal is output as it is from one channel. A signal which is obtained by selectively outputting either one of the positive-phase signal of the test signal and the negative-phase signal of the test signal is reproduced from the other channel. If, when the test signal is positive-phase, the sound is localized between the left and right loudspeakers, the connection polarities of the left and right loudspeakers is attained.

Abstract: There is provided a speaker control apparatus capable of efficiently improving frequency characteristic of a speaker apparatus of phase inversion type, which is originally small in size and high in efficiency. The speaker control apparatus includes a detection section for detecting sound pressure within a speaker apparatus of phase inversion type and generating a sound pressure signal Spo corresponding to the detected sound pressure, a signal processing section for generating a feedback signal Sfb for feedback on the basis of the detected sound pressure signal Spo, a feedback section for feeding back the feedback signal Sfb to an input signal corresponding to sound to be radiated and generating a feedback input signal Ssy, and an amplification section for driving a speaker unit included in the speaker apparatus on the basis of the feedback input signal Ssy and causing radiation of sound.

Abstract: A bass reproduction speaker apparatus of the present invention includes: A cabinet with two openings; a speaker unit disposed at the first opening; a bass enhancement member disposed at the second opening; an amplifier for driving the speaker unit; a first detector for detecting a vibration of diaphragm of the speaker unit; a second detector for detecting a vibration of the bass enhancing member; a current sensing circuit for measuring the current through the speaker unit; and feedback circuits for feeding back the signals from the detectors and the current sensing circuit output to the amplifier.

Abstract: An Automatic Noise Reduction system wherein the Q of the frequency response is reduced using a negative output resistance to substantially eliminate the coil resistance of a speaker in a headset. The resulting system is less sensitive to variations in operating parameters, such as headset fit on a user and component variations. Temperature compensation of a negative output resistance amplifier is introduced to maintain stability over a wide range of operating temperatures. Temperature compensation includes substantially matching the temperature coefficient of the negative output resistance amplifier to the temperature coefficient of the speaker coil.

Abstract: A method and self-tuning circuit for tuning vibratory transducers, broadly including electroacoustic speakers and specifically including the speakers of common back-up alarms used for safety reasons on commercial vehicles and heavy equipment. The self-tuning circuit is physically coupled to the transducer's input terminals and operates by comparing the rising and falling edges of one period of a test waveform elicited from the transducer by the application of a test signal having a test frequency. Depending on the results of this comparison, the test frequency is adjusted by predetermined increments upward or downward until the transducer's resonance frequency has been tightly bracketed though not exactly pinpointed.

Abstract: The method makes possible the determination of loudspeaker parameters in real operation through a measurement of the moving-coil current im and it contains the following steps:

Abstract: A unique, fully integrated, fully programmable, and highly flexible sound distribution system and methodology for providing masking sound, background music, and paging capabilities in up to eight zones of a building or space is provided. The methodology embodied in the system includes internal masking sounds that are uniquely pre-filtered to provide efficient and effective masking of distracting sounds within selectable zones of the space with a minimum masking sound dB sound level and with a pleasant sounding and non-annoying masking sound. The system also incorporates the capacity to be controlled from a remote or local telephone to adjust the volume level in any zone serviced by the system by issuing appropriate DTMF codes from the telephone's keypad. Unique bi-tone diagnostic functions are provided for assuring that the entire system is correctly wired and installed and for troubleshooting operational anomalies.

Abstract: The invention relates to a method for reducing feedback caused by electromagnetic interference between an induction coil and an output transducer, a voltage supply or an amplifier or a combination thereof, the method comprising: producing by means of a filter an equivalent of an electromagnetic feedback path in a system with a pickup coil and subtraction of the equivalent of the feedback signal from the input signal in order to obtain feedback reduction. The invention further relates to a device for implementing the method, the device comprising an induction coil and an output transducer, voltage supply or an amplifier or a combination thereof. The device further comprises filter means for generating an equivalent of an electromagnetic feedgack signal occurring between the induction coil and an output transducer, a voltage supply or an amplifier or a combination thereof and means for subtracting the equivalent from an input signal in order to obtain feedback reduction.

Abstract: A sound producing system includes a loudspeaker to generate an audible signal. A transducer generates a pressure feedback signal from the audible signal. A controller produces a controlled signal for application to the loudspeaker. The controller derives the controlled signal from the pressure feedback signal and an audio input signal. The controlled signal improves the Sound Pressure Level (SPL) frequency response and reduces distortion within a selected bandwidth of the loudspeaker.

Abstract: The active HVAC duct element can be inserted into a HVAC duct for attenuation of noise. The element works with an acoustical series arrangement of a passive acoustical component and an active acoustical component.

Abstract: The invention relates to an improved electro-dynamic loudspeaker.

Abstract: The present invention relates to a distortion reduction system and method for reducing an acoustic distortion in an loudspeaker. The invention involves: a) generating a first sensor signal based on longitudinal displacement of the voice coil from the initial rest position; b) generating a second sensor signal based on longitudinal acceleration of the voice coil; c) processing and combining the first sensor signal and the second sensor signal to generate a feedback control signal; and d) adjusting an audio drive signal supplied to the voice coil to generate the acoustic waveform wherein the audio drive signal is adjusted based on the first feedback control signal.