Abstract: A transducer (1) for producing sound in response to an electrical signal comprises an actuator (2) with a magnet (4) and a coil (5), and a vibration surface (3), for example a loudspeaker cone. The actuator and the vibration surface are mechanically coupled. The transducer (1) is designed to operate at substantially its resonance frequency (f0). This results in a very high transducer efficiency, which is particularly relevant for rendering low audio frequencies.

Abstract: The present invention relates to a method and a device for processing and reproducing an audio stereo signal. The method produces a left output signal for transmission to a left loudspeaker in a loudspeaker pair, which is, or is equivalent to, the sum of the mid input signal (M) and the side input signal (S), the method further produces a right output signal for transmission to a right loudspeaker in said pair, which is, or is equivalent to, the sum of the mid input signal (M) and the side signal (S) phase shifted 180° . The method further being characterized in that at least part of the side input signal (S) or the mid input signal (M) is phase shifted approximately 45°-135° relative to the other signal prior to or at the production of the left and right output signals. The invention further relates to such an audio stereo signal reproduction system.

Abstract: A method for processing a multichannel audio signal. The method includes mounting electroacoustical transducers in a low frequency augmenting device. The electroacoustical transducers radiate different high frequency acoustic energy and common low frequency acoustic energy. The transducers may be part of directional arrays. The method is applied to multimedia entertainment devices.

Abstract: A generating device (1) for generating a useful stream of a medium (2) comprises at least a medium stream source (14) for generating a high-frequency medium stream (15) and at least a medium stream diode (36, 37) for cooperating with the generated medium stream (15), and at least one medium stream sink (40, 41) for cooperating with the medium stream influenced by the medium stream diodes (36, 37), wherein the at least one medium stream sink (40, 41) suppresses high-frequency stream components in the medium stream such that a useful medium stream (2) in a low-frequency range is obtained.

Abstract: A system for decorrelating signals including a first all pass filter, having a first delay length, processing a first signal. A second all pass filter, having a second delay length, is connected to the first all pass filter and processes the first signal after processing by the first all pass filter. A third all pass filter, having a third delay length, processes a second signal. A fourth all pass filter, having a fourth delay length, is connected to the third all pass filter and processes the second signal after processing by the third all pass filter. The first delay length, the second delay length, the third delay length and the fourth delay length each have a unique value, and the sum of the first delay length and the second delay length is equal to the sum of the third delay length and the fourth delay length.

Abstract: The present invention comprises a circuit having at least not less than three cascade connected phase shift circuits and wherein the phase characteristic of the circuit is determined in such a manner that the phase of the audio input signals is gradually delayed depending on logarithmic increase of frequencies in a range of audible frequencies and a phase delay in a range of 450 degree˜600 degree in total in the range of audible frequencies is caused.

Abstract: A method and system for surround sound beam-forming using vertically displaced drivers provides a low cost alternative to present external surround array systems. A pair of vertically displaced speaker drivers is supplied with surround and main channel information in a controlled phase relationship with respect to each driver such that the surround channel information is propagated in a directivity pattern substantially differing from that of the main channel information. The main channel information is generally directed at a listening area, while the surround channel information is directed away from the listening area and is substantially attenuated in the direction of the listening area, so that the surround channel information is heard as a diffuse reflected field. An electronic network provides for control of the surround channel phase relationship and combining of main and surround signals for providing inputs to individual power amplifiers for each driver.

Abstract: A sound reproduction system comprises a left and right speakers located in close proximity, and a sound processor which provides audio signals to the pair of speakers. The sound processor preferably derives a cancellation signal from the difference between the left and right channels. The resulting difference signal is scaled, delayed (if necessary), and spectrally modified before being added to the left channel and, in opposite polarity, to the right channel. The spectral modification to the difference channel preferably takes the form of a low-frequency boost over a specified frequency range, in order to restore the correct timbral balance after the differencing process. Additional phase-compensating all-pass networks may be inserted in the difference channel to correct for any extra phase shift contributed by the spectral modifying circuit. The technique may be used in a surround sound system.

Abstract: A method of operating an electronic video device such as a DVD player, wherein video clock signals and audio clock signals are derived from a system clock signal using two phase-lock loops, and these video and audio clock signals are used to process encoded video data and encoded audio data, but digital-to-analog conversion of the audio data stream is controlled by the system clock signal rather than the audio clock signals. By using the system clock signal to control the audio digital-to-analog converter (DAC), the DAC avoids the poor performance issues that can arise from the jitter introduced into the audio clock signals by the PLL. The system clock signal may be divided by an integer to generate the sampling clock for the audio DAC. In the illustrative embodiment, the system clock signal has a rate which is not an integer multiple of the sample rate of the audio data stream. For example, the system clock rate might be 27 MHz while the sample rate of the audio data stream is 44.1 kHz.

Abstract: The small array microphone apparatus comprises first and second omni-directional microphones, a microphone calibration unit and a directional microphone forming unit. The first and second omni-directional microphones respectively convert sound from a desired near-end talker into first and second signals. The second and first omni-directional microphones and the desired near-end talker are arranged in a line. The microphone calibration unit receives the first and second signals, calibrates on gain, and correspondingly outputs first and second calibration signals. The directional microphone forming unit receives the first and second calibration signals to output a first directional microphone signal with a predefined directivity according to a control signal and a second directional microphone signal with a fixed directivity for noise detection. Determination of the control signal is based on whether environmental noise power generated by an environmental detection unit, exceeds a predefined threshold.

Abstract: A speaker system that includes an audio signal-receiving interface, a modulating circuit, a phase-control circuit, and a number of speaker units. The audio signal-receiving interface is configured to receive an audio signal, and the modulating circuit is coupled with the audio signal-receiving interface. The modulating circuit is configured to modulate a low frequency component of the audio signal and to generate a modulated signal. The phase-control circuit is coupled with the modulating circuit and the audio signal-receiving interface. The phase-control circuit is configured to receive the modulated signal and a high-frequency component of the audio signal and to control a phase of the modulated signal, a phase of the high-frequency component of the audio signal, or both. The speaker units are coupled with the phase-control circuit and configured to generate sound waves based on signals supplied by the phase-control circuit.

Abstract: The invention relates to sonic steerable antennae and their use to achieve a variety of effects. The invention comprises a method and apparatus for taking an input signal, replicating it a number of times and modifying each of the replicas before routing them to respective output transducers such that a desired sound field is created. This sound field may comprise a directed beam, focus beam or a simulated origin. Further, “anti-sound” may be directed so as to create nulls (quiet spots) in an already existing sound field. The input signal replicas may also be modified in way which changes their amplitude or they may be filtered to provide the desired delaying.

Abstract: Systems and methods for wireless signal transfers between ultrasound-enabled medical devices are disclosed. An illustrative system includes a source device equipped with multiple transducer elements configured to transmit an acoustic wave, a target device including an acoustic transducer for receiving the acoustic wave from the source device, and a controller configured to determine adjustments to one or more transmission parameters of the source device for increasing the signal coherence of the acoustic wave at the target device.

Abstract: The user (2) of a binaural hearing aid or communication system (1A, 1B) is to be provided with an easier assignment or identification of acoustic signals generated in the system for keeping a user (2) informed about current settings or states of the system. To this end the signal is emitted by the hearing aid or communication system (1A, 1B) in such a way that for the user (2) the signals appear to come from different signal sources (3 to 6; 8 to 11) in the space (7) surrounding the user. In this way the acoustic signals carry additional information perceived consciously or unconsciously by the user (2).

Abstract: A method and apparatus for conditioning an audio input signal to enhance perception and reproduction of bass frequencies. Harmonics are generated and combined with a phase-shifted version of the audio input signal. Use of a controlled phase shift reduces or eliminates unwanted introduction of waveform asymmetry or D.C. offset.

Abstract: A digital audio signal processing system and method transforms two-channel stereo time-domain data into the frequency domain. Vector operations are performed upon the frequency-domain data by which signal components unique to one of the input channels are routed to one of the output channels, signal components unique to the other of the input channels are routed to another of the output channels, and signal components common to both channels are routed to a third and optionally to a fourth output channel. The frequency-domain output channels are then transformed back into the time-domain, forming an equivalent number of channels of output audio data. The vector operations are performed in a manner that preserves the overall information content of the input data.

Abstract: In a directional speaker control system for realizing good sound localization by correcting the directivity of a directional speaker, adapted to an audio surround system in which a desired sound is reflected on a wall surface or a sound reflection board so as to produce a virtual speaker, a first directional speaker emits a first sound toward the wall surface or sound reflection board so that the reflected sound reaches a prescribed listening position, and a second directional speaker emits a second sound, which comes to have an inverse phase with respect to an audio element of the first sound reaching the listening position directly, toward the listening position. Thus, it is possible to adequately dampen the audio element (particularly, low-frequency components) emitted directly toward the listening position from the first directional speaker; hence, it is possible to realize good sound localization.

Abstract: There is provided a sound processing apparatus for processing received sounds. A plurality of sound receiving units which are included in the apparatus output individually a sound signal corresponding to a received sound, then the sound signals in a time domain are converted into respective converted signal in a frequency domain, and a spectral ratio between the two converted signals is calculated for driving a phase correction value which corrects a phase of the sound signal.

Abstract: A speaker array apparatus includes a speaker array in which a plurality of speaker units are arranged, a storage section that stores installation position information of the speaker array, a position detecting section that detects a listening position of a listener, and a phase controlling section that controls phases of sounds to be emitted from the speaker units so that the speaker array emits sound beams of a plurality of channels. The phase controlling section controls the phases of the sounds on the basis of the installation position information and the listening position of the listener so that the speaker array emits the sound beams of the plurality of channels to form a surround sound field at the listening position of the listener.

Abstract: A loudspeaker system with three loudspeakers (LF, LR, LB), includes a first and a second amplifier (BF, BR), each of which amplifies a channel of an audio signal. The outputs of the amplifiers (FDA, FIA; RDA, RIA) are in phase opposition, wherein the outputs of the amplifiers (RDA, FIA; RDA, FIA) are each connected to the inputs of the first and second loudspeakers (LF, LR). The outputs of the amplifiers (RDA, FIA; RDA, FIA) are also connected to the inputs of the third loudspeaker (LB). A high-pass filter (HP) and a low-pass filter (TP), which are used to partition the audio signal, are connected in parallel. As the amplifiers, bridge output stages (BF, BR) are provided. The output of the high-pass filter (HPA) is connected to the inputs of the two bridge output stages (BF, BR). An inverter (IF, IR) is provided in each case between the output of the high-pass filter (HPA) and one of the inputs of the bridge output stages (BF, BR).

Abstract: A speaker array apparatus includes a speaker array that emits sounds of a plurality of channels, a beam formation calculating section that performs a calculation for controlling phases of the sounds so that the speaker array emits sound beams in directions set for the respective channels, a sound source localization applying section that performs a calculation for controlling the phases of the sounds emitted from the speaker array so as to form a plurality of virtual point sound sources, and performs a calculation of auditory sensation characteristics at a listening position on a basis of a head-related transfer function, a selecting section that selects one of the beam formation calculating section and the sound source localization applying section, and a phase controlling section that controls the phases of the sounds emitted from the speaker array on a basis of a calculation result of the beam formation calculation section which is selected by the selecting section or applies the auditory sensation charact

Abstract: A direct digital drive audio system and method system and method are presented. The direct digital drive system and method utilizes a digital signal to directly drive the speakers. In one exemplary implementation, an audio system includes a sample register, an convergence adjustment component, an accumulated error register, a digital driver and a speaker. The sample register is coupled to the convergence adjustment component which is coupled to the accumulated error register and the digital driver which in turn is coupled to the speaker. The sample register holds an audio sample. The convergence adjustment component calculates the error for each sample. The accumulated error register stores an accumulated error. The digital driver determines whether to drive on a positive digital value, drive on a negative digital value or not drive. The speaker creates audio sounds based upon a signal from the digital driver.

Abstract: The invention relates to a method for recording sound signals of one or more sound sources located in a recording space and having time-variable directional characteristics and for reproducing the sound signals and directional information of the sound sources true to life in an area of reproduction. The invention also relates to a system for carrying out the method. In order to be able to record, transmit and reproduce the directional information of a sound source in real time, only the main direction of emission of the sound signal emitted by the sound source is detected in the recording space in a time-dependent manner and reproduction is carried out depending on the detected main direction of emission. In order to convey the directional information, the sound signals are reproduced by means of a first reproduction unit associated with the sound source and at least one second reproduction unit spaced apart from the first reproduction unit.

Abstract: The sound reproduction system provided for in-vehicle use includes: a music signal source; a first group of a first transducer, a second transducer, a third transducer and a fourth transducer connected to the music signal source; a signal processor to shift the phase of first sound signals output from the music signal source; and a second group of a first transducer, a second transducer, a third transducer and a fourth transducer connected to the signal processor.

Abstract: A single folded, expanding horn loudspeaker reproduces low frequency audible sound at high power output levels. A compact enclosure houses a plurality of identical transducers, characterized by small vibrational surface areas. The throats for each transducer into the horn are acoustically differentially spaced from the mouth of the horn. Transducer drive circuitry adjusts a drive signal for the transducers to compensate for the different impedance and propagation time to the horn mouth at each throat.

Abstract: An auditory sense training device 1 to be used in an auditory sense training method for training auditory sense by listening to a sound formed by processing an original sound comprises a band attenuation processing method 20 for attenuating a predetermined frequency band of an original sound 10, a switching means 30 for selectively outputting either the original sound or the output from said band attenuation processing means, a panpot processing means 40 for performing a panpot process wherein a voice signal formed by attenuating an original sound of one channel is superposed to the original sound of another channel, and a phase reverse processing means 50 for performing a phase reverse process of reversing the phase of the original sound, wherein a trainee listens to the original sound and a band attenuation processed sound formed by attenuating a predetermined frequency band of the original sound alternately.

Abstract: The invention relates to an assembly of acoustic transducers, a system and a method for receiving and reproducing sound. The assembly comprises a first acoustic transducer having a directional pattern of the shape of a figure of eight in the direction of an X axis of a XYZ coordinate system, and a second acoustic transducer placed perpendicularly relative to a first capsule and providing a directional pattern of the shape of a figure of eight in the direction of a Y axis of a XYZ coordinate system. The assembly is characterized in that it further comprises a third acoustic transducer placed perpendicularly relative to the first and second acoustic transducers, enabling the implementation of spatial sound both in a XY plane and in a XYZ plane by using these acoustic transducers placed in accordance with an axis of the axes of the XYZ coordinate system. The invention further provides a system and a method for processing signals received with the assembly.

Abstract: A low-noise directional microphone system includes a front microphone, a rear microphone, a low-noise phase-shifting circuit and a summation circuit. The front microphone generates a front microphone signal, and the rear microphone generates a rear microphone signal. The low-noise phase-shifting circuit implements a frequency-dependent phase difference between the front microphone signal and the rear microphone signal to create a controlled loss in directional gain and to maintain a maximum level of noise amplification over a pre-determined frequency band. The summation circuit combines the front and rear microphone signals to generate a directional microphone signal.

Abstract: Combining audio channel signals includes shifting the phase of a first audio signal relative to a second audio signal. In one embodiment, the relative phase shifting is substantially limited to a predetermined frequency range.

Abstract: High and low frequency components Cn1, Cn2 are generated by causing a center channel audio signal Cn to pass through a high-pass filter HPF and a low-pass filter LPF, and the high frequency component Cn1 is supplied to the center channel loudspeaker SPC. Also, two low frequency components Cn2L, Cn2R, which have a different phase mutually, are generated by causing the low frequency component Cn2 to pass through phase shifters 2, 3. An synthesized audio signal SL is generated by synthesizing the low frequency component Cn2L and the front-left channel audio signal FL, and then supplied to the front-left channel loudspeaker SPL. An synthesized audio signal SR is generated by synthesizing the low frequency component Cn2R and the front-right channel audio signal FR, and is supplied to the front-right channel loudspeaker SPR.

Abstract: An artificial stereophonic circuit which includes a monophonic signal input terminal, a signal output terminal of one of an L channel and an R channel which are connected to the signal input terminal, a phase-shifting circuit having an input side connected to the signal input terminal, and a signal output terminal of the other channel of the L channel and the R channel having an output side connected to the phase-shifting circuit. The phase-shifting circuit has an almost equal gain in a full frequency band of an input signal, and a phase shift for a change from 0 to 180 degrees according to an increase in a frequency of the input signal is carried out. The change of the phase can be minimized and a natural stereophonic effect can be realized. Moreover, only one capacitor is enough and only one pin for external attachment is enough for wholly forming an IC.

Abstract: The stereophonic sound system attenuates the audio power level delivered to the auxiliary speakers relative to the audio power level delivered to the main speakers so that the radiated sound pressure level from the auxiliary speakers is less than the radiated sound pressure level from the main speakers; blocks the tow frequency audio power from being delivered to the auxiliary speakers; and shapes the radiated dispersion pattern by controlling the phase relationship between the auxiliary speakers and the main speakers. This system widens the stereophonic sweet spot, eliminates soundstage shift, corrects off-axis response, and improves off-axis phantom image specificity, thus improving stereophonic realism over and above the present art. Stereophonic “realism” is a subjective assessment of the degree to which the sound from an audio system approaches that of live music.

Abstract: A method of providing sounds in phase to a listener in an audio system by adjusting sounds with respect to the position of the listener includes generating first and second audio signals having identical magnitudes and opposite phases, and delaying the first audio signal from the second audio signal for a time corresponding to a predetermined delay constant, providing the first and second audio signals to first and second sound transform units, respectively, collecting a synthesized sound generated through a synthesis of first and second sounds corresponding to the first and second audio signals from the position of the listener, and determining a magnitude of the synthesized sound, and obtaining a delay constant to minimize the magnitude of the synthesized sound by repeatedly performing the generating of the first and second audio signals, the providing of the first and second signals, and the determining of the magnitude of the synthesized sound with a plurality of delay constant values; and an apparatus to

Abstract: Electroacoustical apparatus includes at least first and second acoustically coupled electroacoustical drivers. An electrical network couples their inputs so that an electrical drive signal applied to one reduces the effect of acoustic coupling from that one to the other.

Abstract: Apparatus, methods and articles of manufacture are disclosed for modifying electromagnetic waves by reducing noise in those waves. A transfer function for a plurality of segments is derived through identifying a desired output parameter. That transfer function is then applied, via a plurality of filters or other devices, to a wave, in order to achieve said transfer function.

Abstract: High and low frequency components Cn1, Cn2 are generated by causing a center channel audio signal Cn to pass through a high-pass filter HPF and a low-pass filter LPF, and the high frequency component Cn1 is supplied to the center channel loudspeaker SPC. Also, two low frequency components Cn2L, Cn2R, which have a different phase mutually, are generated by causing the low frequency component Cn2 to pass through phase shifters 2, 3. An synthesized audio signal SL is generated by synthesizing the low frequency component Cn2L and the front-left channel audio signal FL, and then supplied to the front-left channel loudspeaker SPL. An synthesized audio signal SR is generated by synthesizing the low frequency component Cn2R and the front-right channel audio signal FR, and is supplied to the front-right channel loudspeaker SPR.

Abstract: A sound reproducing apparatus includes a low-frequency sound reproducing unit for reproducing and outputting a low-frequency sound having a frequency of a predetermined frequency or less; a high-frequency sound reproducing unit for reproducing and outputting a high-frequency sound including a frequency component having a frequency higher than the predetermined frequency; and a reproduction-and-output timing control unit for reproducing and outputting the high-frequency sound reproduced and output by the high-frequency sound reproducing unit behind the low-frequency sound reproduced and output by the low-frequency sound reproducing unit by a predetermined time period.

Abstract: A sound reproducing apparatus is provided with a circuit comprising a first secondary phase shifter in a front stage of at least one of channels among a first power amplifier, a second power amplifier and a third power amplifier, and a second secondary phase shifter and an adder in at least one of remaining channels for providing an output by adding output signals of a music signal source and the second secondary phase shifter. The apparatus of this structure eliminates phase interferences between a center speaker and right and left speakers by controlling sound waves generated by the center speaker, thereby achieving excellent reproduction of music.

Abstract: A sound reproduction system comprises a left and right speakers located in close proximity, and a sound processor which provides audio signals to the pair of speakers. The sound processor preferably derives a cancellation signal from the difference between the left and right channels. The resulting difference signal is scaled, delayed (if necessary), and spectrally modified before being added to the left channel and, in opposite polarity, to the right channel. The spectral modification to the difference channel preferably takes the form of a low-frequency boost over a specified frequency range, in order to restore the correct timbral balance after the differencing process. Additional phase-compensating all-pass networks may be inserted in the difference channel to correct for any extra phase shift contributed by the spectral modifying circuit. The technique may be used in a surround sound system.

Abstract: A method and apparatus for creating a third signal channel from an input signal received in each of a first and second channel involves inverting a predetermined frequency range of signals in the first channel out of phase with a corresponding frequency range of signals in the second channel. Thereafter, the inverted signal in the first channel and the corresponding frequency signal in the second channel may be communicated to a speaker, which is bridged across the first and second channels, as the third signal channel. This speaker produces sound corresponding to the difference (i.e., the frequency range determined by the predetermined bandwidth of the inverted signal) between the inverted signal in the first channel and the corresponding frequency signal in the second channel.

Abstract: An audio signal processing circuit for an audio reproduction apparatus at least having sound source located substantially at left and right sides to a listener, is provided. The audio signal processing circuit includes a phase difference control portion. The phase difference control portion receives a left channel signal for the left sound source and a right channel signal for the right sound source, controls a phase difference between the left and right channel signals so as to produce a relative phase difference in the range of 140 degrees to 160 degrees, and outputs the phase difference controlled left and right channel signals for the left and right sound source, respectively.

Abstract: A system and method are described for rendering a left rear surround input signal at a left rear virtual speaker location and rendering a right rear surround input signal at a right rear virtual speaker location. The method includes phase shifting the left rear surround input signal by a first phase shift. The right rear surround input signal is phase shifted by a second phase shift. The phase shifted left rear surround input signal is phase shifted using an HRTF selected to render the left rear surround input signal at the left rear virtual speaker location. The phase shifted right rear surround input signal is transformed using an HRTF selected to render the right rear surround input signal at the right rear virtual speaker location.

Abstract: The invention concerns a method for transmitting in an area (100) information items in the form of sound waves representing a signal X(t), through a loudspeaker enclosure (2), said method comprising a step of setting up a public address system which consists in applying to the input of the loudspeaker enclosure (2) an electric signal P(t)=W(t) ?X(t) wherein is the convolution product and W(t)=S(?t)? I(t), wherein S(?t) is the temporal return of the pulse response S(t) between the enclosure and the target zone (101) belonging to the area to be fitted with a P.A. system (100) t representing time, and I(t) is the temporal response of the product e?2inft0.Sc (f), wherein f represents the frequency, t0 is a constant Sc(f)=1/(S1(f))?, ? being a non-null positive number and S1(f) being a real function obtained by peak clipping of the modulo I S(f) I of the frequency response S(f) of S(t).

Abstract: A sound reproduction device of the present invention includes: a first loudspeaker; a second loudspeaker; a first loudspeaker drive section for driving the first and second loudspeakers, the first loudspeaker drive section drives the first and second loudspeakers at substantially the same phase in a first frequency band, and the first loudspeaker drive section drives the first and second loudspeakers at substantially inverse phase and substantially different amplitude levels in a second frequency band higher than the first frequency band.

Abstract: The invention is directed to a sound system with four loudspeakers and at least one signal processing device connected to the input of two loudspeakers and controlled by two input signals. The signal processing device produces control signals for the loudspeakers. The respective control signals are equal to the sum of the input signals which are weighted differently with respect to amplitude and phase, so that the radiation characteristic of the two loudspeakers depends on the weighting of the input signals.

Abstract: An apparatus is provided for matching the response of a pair of microphones. The two microphones provide a first and second output, respectively, in response to an audible input. The microphone outputs are subtract from each other to produce a gain control output for operably controlling the gain of the first microphone output, resulting in a gain compensated microphone output. A phase adjustment circuit also is provided responsive to the gain compensated microphone output and a rolloff control output for producing a matching output. The rolloff control output is generated by a phase difference subtractor circuit responsive to both the matching output and the second microphone output. Moreover, the output of at least one of the microphones has a resonance frequency that is shifted to a desired preselected frequency.

Abstract: A single loudspeaker has a substantially single-point source of sound energy derived from multiple drivers to provide a surround sound effect. The surround sound is effective for listeners close to the single loudspeaker or substantially distant within a room. The physical size of the loudspeaker is convenient for placement on top of a computer monitor or television set. The single loudspeaker produces a dynamically variable energy gradient between the listener's right and left ears and the perception of sound emanating from changing locations in the space surrounding the loudspeaker. The placement of a plurality of these loudspeakers surrounding the expected listener location allows the coverage of larger spaces with separate dynamically variable energy gradient pairs.

Abstract: The invention relates to a loudspeaker combination comprised of at least two loudspeakers, of which one is preceded by a low-pass frequency filter, the other by a phase shifter in the form of an all-pass filter. The invention addresses the problem of providing with simple means a configuration simple of realization of such a loudspeaker combination, whose frequency response and whose radiation characteristic is significantly improved. The invention resides therein that the other loudspeaker or the other loudspeakers is/are each preceded by at least one phase shifter, with all phase shifters being tuned with respect to their phase setting to the phase position of the loudspeakers radiating lower tones, such that all loudspeakers radiate the low tones in like phase position.

Abstract: An audio tone-control circuit includes 4th-order low-pass, 4th-order band-pass, and 4th-order high-pass filter circuits. The 4th-order low-pass filter circuit has a first phase response and receives and filters an audio signal and generates a first output signal therefrom. The 4th-order band-pass filter circuit has a second phase response that is substantially equal to the first phase response and receives and filters the audio signal to generate a second output signal. The 4th-order high-pass filter circuit has a third phase response substantially equal to the first and second phase responses and receives and filters the audio signal to generate a third output signal. The audio-signal circuit also includes a combining circuit that combines the first, second and third output signals into a combined signal. Furthermore, the filter circuits may be 2nd-order filter circuits instead of 4th-order filter circuits.

Abstract: A low cost, reliable and accurate audio frequency phase detection system and method includes an audio signal source generating an audio frequency test signal and a phase detector detecting phase reversals in the audio frequency test signal. The signal source may be an active, real time signal generator or a recorded media player playing back a prerecorded signal. The test signal is provided to a user system while the phase detector determines whether or not a phase reversal has occurred in the test signal between the input and output of the user system and illuminates a green or red LED to indicate whether or not a phase reversal has occurred. The test signal includes a lower frequency signal component and a higher frequency signal component that provides a marker for testing the phase of the lower frequency signal component.