Abstract: A method and system for utilizing multiple speakers in a portable electronic device is disclosed. The method includes receiving an input at a user interface of a portable electronic device, switching a first and second speaker in a stereo configuration to a mono configuration by routing a first digital to analog converter (DAC) output to both the first and second speaker in response to the input and coupling a third speaker to a second DAC to receive a first audio signal that is responsive to the input. The system includes a first digital to analog converter coupled to a first speaker, a second DAC coupled to a second speaker, and a third speaker. The system further includes switching logic coupled to the first and second DACs. The switching logic is responsive to an input signal provided by a user interface of a portable device. In response to an input signal from the user interface, the switching logic couples the first and second speakers to the first DAC and the third speaker to the second DAC.

Abstract: A sound signal processor and a method for processing a sound signal using the same enables the elimination of a plop noise generated in the course of a sound mode checking operation. The sound signal processor receives a sound intermediate frequency (SIF) signal and includes a channel mode discriminator for determining a current sound mode of the received SIF signal; a mode transition checker for performing a checking operation to determine whether the current sound mode has resulted from a transition from a first sound mode to a second sound mode; an amplitude measurement circuit for measuring an amplitude of the received SIF signal; and a controller for controlling a drive of the mode transition checker according to the measured amplitude. If the sound channel mode of a currently input sound signal is a mono channel mode, the amplitude of the input sound signal is measured, and the measured amplitude is compared to a reference level.

Abstract: A method of denoise a stereo signal comprising a stereo sum signal and a stereo difference signal, performs a frequency selective stereo to mono blending based on the masking effect of the human auditory system. Therefore, a stereo signal noise reducer, comprising a first filter bank (1) to split the stereo difference signal (l?r) into a plurality of subbands, respective first multipliers (CO, . . . , CN) to weight each of the subbands of the stereo difference signal with a respective corresponding control signal (CO, . . . , CN), and a first adder (3) to sum all weighted subbands of the stereo difference signal (l?r) to build a frequency selective weighted stereo difference signal (diff), within which a number and width of the subbands obtained via the first filter bank (1) are choosen according to the properties of the human auditory system, further comprises a weighting factor determination unit which determines a respective control signal (CO, . . .

Abstract: Aspects of the method and system for rejecting single sided leakage into an amplitude modulated channel may comprise an AM demodulator for demodulating a received composite broadcast signal's control channel to generate an amplitude modulated (AM) component. A PM demodulator may demodulate a received composite broadcast signal's control channel to generate a phase modulated (PM) component. At least one subtractor may subtract an AM leakage component and a PM leakage component contributed by the single sided leakage in the received composite broadcast signal's control channel. The system may comprise at least one of each of AM and PM bandpass filters and envelope detectors that filter and detect envelopes of the AM and PM components at 982.5 Hz and 922.5 Hz.

Abstract: A stereo headset interface that is compatible with mono for an audio playback device. A load in series between an audio output from a stereo headset driver and a ground of a mono headset plug prevents the audio output from being grounded when a mono headset plug is inserted into the stereo headset jack of the playback device. A second load in series between a second audio output and the mono headset plug balances the first and second audio outputs from the stereo headset driver.

Abstract: A Japanese BTSC audio broadcast signal has three modes of transmission: mono, stereo, or dual mono. The control channel centering at 3.5 fH is one of the three channels in the J-BTSC signal, and contains information to indicate to the decoder which one of the three modes the audio transmission is in. The present invention uses a bandpass filter directly in the AM band, followed by envelope filtering and a decision circuit. Therefore, the need for AM demodulation and AM carrier detection is eliminated.

Abstract: A recording medium has a first recording area on which multiplexed audio informations are recorded as sets of one or more information units, a second recording area on which control information for controlling recording of the multiplexed audio informations are recorded. The control informations include first information representing the number of sets of information composing the multiplexed audio informations, and second information instructing to record the multiplexed audio informations as a stream.

Abstract: Disclosed are an apparatus and a method for controlling an input signal level. The apparatus for controlling an input signal level according to the present invention includes: a memory for storing a current input signal level, a previous input signal level, a maximum change value, a maximum no-change value, a change counter value and a no-change counter value; a determining unit for determining whether the values stored in the memory are identical; and a control unit for reading out the values stored in the memory to output them to the determining unit and storing a predetermined level as the current input signal level based on the determination by the determining unit. The present invention can maintain an input signal at a predetermined level and thereby ensure stability of a device to which the level is applied and stability of a signal outputted from the device.

Abstract: A method and ASIC for canceling crosstalk between a first stereo channel and a second stereo channel, wherein a first signal is input to a first output amplifier for the first channel, and a second signal is input to a second output amplifier for the second channel, and an output load for each output amplifier is connected between each output amplifier and a reference amplifier. In one embodiment, the first and second signals are split prior to inputting the signals to the first and second output amplifiers, and a gain-adjusted portion of each signal is added to the other signal on the inputs of the output amplifiers. In another embodiment, the first and second input signals are again split into two paths each. While a first path of each signal is inputted to each signal's respective output amplifier, the second paths of the first and second signals are adding together. The resulting sum is adjusted by a gain function, biased by a suitable DC voltage, and input to the reference amplifier.

Abstract: A FM broadcast compander system is combined with a conventional denoising system suited for FM receiver, wherein a noise indicator is determined by a subtraction of the conventionally transmitted difference signal Ud(z) from the additionally transmitted difference signal (Uc(z)) which is additionally transmitted according to the companding system. This system gives a noise reduction of 20 dB in a stereo FM broadcast receiver.

Abstract: A method to denoise a stereo signal which comprises a stereo sum signal (Us(z)) and a stereo difference signal (Ud(z)), wherein a stereo to mono blending on basis of an attenuation of the stereo difference signal (Ud(z)) is performed, determines an attenuation of the stereo difference signal (Ud(z)) under consideration of the difference signal amplitude. Therefore, a stereo signal noise reducer which performs a stereo to mono blending on basis of an attenuation of the stereo difference signal, comprises an attenuation factor determination unit which determines an attenuation factor (Hatt) under consideration of the difference signal amplitude.

Abstract: The components of a portable personal audio system include first and second audio signal source devices, such as an MP3 player (14) and telephone (16). These are connected via respective leads (12) to a control and switching stage (22), and from there to left and right audio output devices (26). User input to effect operation of the control and switching stage (22) selectively directs audio signals from one or both of the signal source devices (14, 16) to a selected one or ones of the left and right audio output devices (26).

Abstract: For the purpose of largely suppressing the noise pulses caused in a stereo radio receiver in the reception signal, particularly by the ignition system of a motor vehicle, a digital field strength signal representing the analog field strength signal is produced for example by digitizing the analog field strength signal. The scanning values of the digital audio signal, for example of the (L+R) signal, are produced by interpolation for at least as long as the digital field strength signal is outside a presettable tolerance range.

Abstract: When a plug of a monaural microphone is connected to an external microphone input section, a right channel terminal is connected to a GND terminal, and a voltage Vdet will be a GND potential. A DC voltage detection section detects this GND potential, and outputs, for example, an H level signal as a detection signal. In response to this detection signal, a system control section controls a DSP so that, for example, an audio signal of the left channel is recorded by use of both right and left recording channels.

Abstract: Audio source selection circuit (QW) for an audio signal processor with inputs for source signals (F1, F2, NA, NB) provided by at least one source (Q1, Q2), with a processing device (V) which forms pairs of signals from the source signals, with a settable source selection logic (Qs) to which the channels of the processing device (V) are applied, and with outputs coupled to signal outputs of the settable source selection logic (Qs) and each forming an output channel (Co1, Co2, Co3), the processing device (V) including an automatic audio mode setting device which generates suitable intermediate channels (Cz1, Cz2, Cz3, Cz4) from the source signals (F1, F2, NA, NB) according to a source- and application-related mode.

Abstract: A method to denoise a stereo signal comprising a stereo sum signal and a stereo difference signal, performs a frequency selective stereo to mono blending based on the masking effect of the human auditory system. Therefore, a stereo signal noise reducer, comprising a first filter bank (1) to split the stereo difference signal (1?r) into a plurality of subbands, respective first multipliers (20, . . . , 2N) to weight each of the subbands of the stereo difference signal with a respective corresponding control signal (C0, . . . , CN), and a first adder (3) to sum all weighted subbands of the stereo difference signal (1?r) to build a frequency selective weighted stereo difference signal (diff), within which a number and width of the subbands obtained via the first filter bank (1) are choosen according to the properties of the human auditory system, further comprises a weighting factor determination unit which determines a respective control signal (C0, . . .

Abstract: A dual purpose loudspeaker incorporating at least two audio signal inputs and at least one switch is adapted to receive and reproduce either a single audio signal input or two audio signal inputs according to the position of the switch. A switch slide mechanically linked to the switch is provided which blocks one of the audio signal inputs when the switch is in the single-channel position, thereby preventing erroneous connection to the blocked audio signal input.

Abstract: The invention intends to provide an audio output control circuit capable of reproducing the audio signals inputted to the external input terminals in the multi-channel audio reproduction system with a simplified circuit configuration. The control circuit furnishes the external input terminals with a detection circuit composed of a switch for electrically connecting both of the external input terminals, and a switch circuit. The switch is in a connection state in the normal condition, but when a plug is inserted into the one of the terminals, the switch is made disconnected. When the plug is inserted only into the other one of the terminals, and the monaural signal is inputted, the same monaural signal is outputted from the two terminals. The switch circuit being put in ON and OFF by a current from the other one of the terminals detects the insertion state of a plug.

Abstract: The invention relates to a method, signal processing device and computer program for stereo widening (SW) of stereo format signals to become suitable for headphone listening. The invention also relates to a mobile appliance performing signal processing according to the invention. According to the invention a separate monophonic signal path (ME) is formed in order to equalize the frequency spectrum of the monophonic component of the left and right output signals (Lout,Rout) by at least extracting from the left and right input signals (Lin,Rin) an at least substantially monophonic signal component contained in said signals (Lin,Rin), processing the extracted monophonic signal component to obtain a processed monophonic signal component, and combining said processed monophonic signal component with at least one of the left (Lout) or the right (Rout) output signals.

Abstract: Comprising:

Abstract: A portable computer system includes an audio circuit and a common audio input socket coupled to the audio circuit. This audio circuit has a controller and two amplifiers. Two types of external audio devices is to be coupled to the common audio input socket. The controller controls the two amplifiers alternately depending upon the audio type of the external audio device coupled to the common audio input socket. In a preferred embodiment, a first amplifier is provided for amplifying stereo audio signals and a second amplifier for amplifying a mono audio signal. When the controller detects a mono audio device, the microcontroller disables the first amplifier. Detecting a stereo audio device, the controller disables the second amplifier.

Abstract: A stereo headphone employing a standard stereo headphone plug is adapted for automatically hearing a monaural signal at both earpieces, when accessing a typical monaural source. In the first embodiment of the invention, an impedance element couples the signal from a first acoustical driver that receives the monaural signal from the stereo plug tip, to a second acoustical driver that is connected to the stereo plug ring and normally receives no signal when plugged into a conventional monaural audio source output jack. The magnitude of the coupling impedance is selected with respect to the impedance of the acoustical driver so that the reduction in loudness at the second earpiece due to the signal voltage drop across the coupling impedance is not perceptible to the listener. This will occur when the reduction in loudness at the second earpiece is less than the threshold of perceivable loudness reduction at one ear when there is no reduction in loudness at the other ear.

Abstract: A monaural and stereo audio signal control system for use in cable-signal set-top boxes selects signal processing paths as a function of the monaural and stereo nature of the incoming audio component of the television signal and an indication as to whether the audio component is a “clear” or “masked” signal. A clear audio signal is a signal that conforms to a NTSC or BTSC standard that can be processed by a conventional television receiver while a “masked” signal is one in which the carrier frequency has been changed or otherwise modified so that a conventional television receiver cannot extract the audio content. A signal-processing path is provided for conventional clear monaural and stereo audio and for a masked monaural signal and for a masked stereo signal.

Abstract: A stereo radio receiver has a channel separation stage for setting an optimal channel separation of the left audio channel from the right audio channel, even under sufficient receiving field strength following a time of multipath reception for the duration of the operating time of a timing element, to a reduced (i.e., lesser degree of) channel separation.

Abstract: Part of the (synthetic material) substrate (8) of a display is combined with a light source, e.g. a LED (14) and a photodetector (20) to be used as an optical microphone. A membrane (11) is formed which deforms due to air pressure fluctuations caused by sound waves. The fluctuations are detected by the photodetector for further processing.

Abstract: The sound reproduction of a multichannel sound reproduction system with a plurality of speakers which is connected to the output of an FM stereo receiver is controlled by a control signal derived from the reception quality. Preferably, the control signal from the FM stereo receiver for controlling the stereo and mono components is also employed to control the multichannel sound reproduction system. For example, stereo, pseudo-stereo or mono reproduction are provided in the multichannel sound reproduction system in response to the stereo component within the output signal.

Abstract: An audio system has multiple amplifiers, each with power supply inputs and audio inputs and outputs, for driving audio speakers according to a selected one of at least two modes of operation in which a selection of the audio speakers and/or a required power output of the audio speakers differ between the modes. The invention is operable, for example, to an entertainment system that has internal and external speakers and associated amplifiers for switching between stereo and surround sound modes. At least two distinct power supply voltage sources are provided for the amplifiers, and a switching element operates upon switching between the modes to couple one or another of the distinct power supply voltage sources to the power supply inputs of respective ones of the at least two amplifiers. This the total audio output of the system from increasing, for example, when switching from two stereo outputs to five surround sound outputs.

Abstract: The present invention discloses a differential audio device applicable to notebook computers. The device uses differential signal characters to improve the audio signal quality and its transmission distance. The device contains at least an audio controller to output audio signals, a single-ended signal to differential signal converter to convert audio signals into differential signals, a differential signal to single-ended signal converter to convert differential signals into audio signals for output.

Abstract: A stereo headphone employing a standard stereo headphone plug is adapted for automatically hearing a monaural signal at both earpieces, when accessing a typical monaural source. In the first embodiment of the invention, an impedance element couples the signal from a first acoustical driver that receives the monaural signal from the stereo plug tip, to a second acoustical driver that is connected to the stereo plug ring and normally receives no signal when plugged into a conventional monaural audio source output jack. The magnitude of the coupling impedance is selected with respect to the impedance of the acoustical driver so that the reduction in loudness at the second earpiece due to the signal voltage drop across the coupling impedance is not perceptible to the listener. This will occur when the reduction in loudness at the second earpiece is less than the threshold of perceivable loudness reduction at one ear when there is no reduction in loudness at the other ear.

Abstract: Audio-processing devices are known generally. When such an audio device wants to use as input signals from another device de audio device has to determine whether the received input signals are mono signals or stereo signals.

Abstract: The components of a portable personal audio system include first and second audio signal source devices, such as an MP3 player (14) and telephone (16). These are connected via respective leads (12) to a control and switching stage (22), and from there to left and right audio output devices (26). User input to effect operation of the control and switching stage (22) selectively directs audio signals from one or both of the signal source devices (14, 16) to a selected one or ones of the left and right audio output devices (26).

Abstract: Monaural inputs are accepted for presentation to a pair of speakers. The output sound image from that pair of speakers is such that a listener will perceive that the sound is stereo and that certain sounds come from a non-existent center speaker and that other sounds come from locations beyond the physical boundaries of the two speakers. The system operates to preserve full tone range at both speakers and does not split the sound from a particular instrument between both speakers. The system can be used to provide sound signals to the rear speakers of a multiple speaker system when the sound input to the rear speakers is either monaural or stereo.

Abstract: In a stereo decoder, channel separation takes place with the aid of a demodulator to acquire signals for stereo operation. At low received field strength there is a continuous switchover to mono operation for each channel in the demodulator. For this purpose a switch is located in a signal path between input and output of the demodulator and driven by a PWM signal whose pulse-width repetition rate determines whether solely mono operation, solely stereo operation or a mixture of the two takes place. For generating the PWM signal, the field strength signal is compared with a triangular signal. To permit the switchover points between stereo and mono operation to be aligned by the manufacturer in accordance with the amplitude of the field strength signal, the apparatus contains two limit storage registers in which digital limit signals are set from outside.

Abstract: In the case of a switching arrangement for mobile radio receivers having a device for adjusting the stereo playback portion relative to the mono playback portion as a function of multipath effects, the resetting time of mono to stereo playback is a function of the relative frequency, intensity and length of multipath effects.

Abstract: A multipath interference reduction system and method for smoothly reducing noise associated with FM stereo signal reception with an adjustable blend. The system includes a peak detector for detecting noise present in the received signal. When the detected noise exceeds a first threshold limit, stereo separation reduction is provided. The amount of stereo separation reduction may be adjusted so as to provide a greater reduction at higher noise frequencies than at lower noise frequencies to enhance the audio sound. When the determined noise exceeds a second higher threshold limit, stereo separation is further reduced to provide primarily monoaural reception.

Abstract: In a circuit for mobile radio receivers with a device for setting the stereo reproduction portion relative to the mono reproduction portion as a function of changes in the reception field strength, the setting time for the transition from stereo to mono reproduction and vice-versa depends on the reproduction volume and/or dynamic response of the radio signal.

Abstract: In a mono/stereo input circuit for use in an audio equipment, and more particularly in a circuit for automatically recognizing and receiving mono/stereo audio signals, although a mono connector is inserted into a stereo jack, such an insertion of the mono connector is automatically recognized and then a stereo circuit can operate as a form of a mono circuit. The circuit for automatically recognizing and receiving the mono/stereo audio signals utilizes a fact that one connection terminal of the jack is grounded or not according to a type of the connector such as a mono connector and a stereo connector which is inserted into the jack. Accordingly, a resistor used as a voltage generator generates a generation voltage according to such a connector recognition. Also, using a difference between the generated voltage, the analog switches are turned on or off, to obtain a mono or a stereo audio signal processing circuit according to a type of the inserted connector.

Abstract: A mono/stereo switching circuit wherein first, second, and third switches operate in circuit which is arranged so that (1) when the first switch is engaged, and the mono/stereo switch is engaged, the signal at a first mono input is provided to both of a pair of left and right output channels; (2) when the second switch is engaged and the mono/stereo switch is not engaged, the signal at a second mono input is provided to both of the pair of left and right output channels; and (3) when the input signal is a stereo signal at the first and second inputs, and either of the first and second switches is engaged, and the mono/stereo switch is engaged, the input signal at the first input terminal is provided at the left channel output while the input signal at the second input terminal is provided at the right channel output.

Abstract: A circuit for controlling the audio signal output of a television, in which it is determined whether video and audio signals are input from an external source, such as a video tape recorder. If so, then the audio output signals are properly controlled according to whether the audio signal are mono or stereo-type signals. The circuit includes an audio input state detecting circuit for determining the audio input state by employing an exclusive OR gate and at least two analog/digital converters, and a video signal detecting circuit for detecting whether or not video signals are input. A switching circuit performs switching operations through an AND gate which logically combines the output of the audio signal state detecting circuit and the output of the video state detecting circuit. Therefore, even in the case where the audio signal is a mono-type signal, a quasi-stereo sound is output through both left and right speakers.

Abstract: Pressure variation of combustion noise is detected by a microphone set in a combustion chamber, and the pressure propagation characteristic for the path from the gas flow control valve to the microphone is identified while the combustion apparatus is operating, and then an adaptive control is made using one signal detected by an microphone and the other signal produced by passing the signal of the microphone through a filter, and then a corrected anti-phase signal of a combustion noise is computed by the coefficient updating circuit, and the computed result is inputted to a gas flow control valve.

Abstract: A noise control system for a FM stereo receiver senses the presence of noise outside of the FM stereo transmission bandwidth at an output of a FM detector and uses variations of amplitude of the sensed noise to control stereo channel separation and audio bandwidth control circuits of a stereo decoder circuit of the stereo receiver.

Abstract: A music/voice discriminating apparatus is composed of a signal processing portion for effecting the signal processing upon input acoustic signals, a music/voice deciding portion for discriminating whether the input acoustic signals are music or voice, a first signal processing portion for optimally setting acoustic parameters for the signal processing respectively for music or voice, and a second signal processing portion for controlling the acoustic parameters of the first signal processing portion in accordance with the decision results of the music/voice deciding portion so that it may become a desirable value set in the second parameter setting portion.

Abstract: A circuit selectively sets a left/right monaural playback channel in a digitally signal-processed stereo audio apparatus. The circuit includes a channel selecting signal generator for generating a channel selecting signal to select the channel corresponding to a signal desired to be reproduced among the audio signals of several channels, a storage circuit synchronous to a predetermined clock signal and temporarily storing the audio signals of several channels, a path controlling circuit for controlling the paths of an audio signal supplied after being processed into a digital signal and a signal output from the storage circuit to transmit to a D/A converter the signals corresponding to the channels selectively set by the channel selecting signal generator, and a control circuit for outputting to the channel selecting signal generator the control signal for selecting a desired channel to be reproduced in response to user commands, and controlling the generation of a channel selecting signal.

Abstract: In a home bus system control signals and information signals are carried between a transmission station at one location and reception stations at other locations. There are plural signal sources at the transmitting station and plural types of signal formats, such as monaural and stereo or NTSC and HDS. A request signal sent from a receiving station identifies the signal source to be accessed and the signal format capability of a receiver at the receiver station. The request signal is decoded at the transmission station and causes transmission of an information signal from the selected signal source in the identified signal format.

Abstract: An FM stereophonic receiver including an FM detector circuit for detecting an intermediate frequency signal, and for providing a main signal and a sub signal in response to the detected intermediate frequency signal, a first high cut circuit, connected to receive the main signal, for providing a first high cut signal, a high cut control circuit for providing a high cut control signal in accordance with a received signal field strength level, the first high cut circuit controlling a frequency characteristic of the main signal in accordance with the high cut control signal, a second high cut circuit for providing a second high cut signal, a separation control circuit for providing a separation control signal in accordance with the received signal field strength level, the second high cut circuit controlling a frequency characteristic of the sub signal in accordance with the separation control signal, and a stereophonic demodulation circuit for providing separated right and left channel signals.

Abstract: A surround processor adapted to apply a stereo surround processing and a monaural surround processing to audio input signals of two channels to provide surround processed outputs, wherein a stereo/monaural discrimination output based on inputted audio signals of two channels is caused to have a predetermined time constant to provide a mixture ratio control signal to change a mixture ratio between a stereo surround processing output signal and a monaural surround processing output signal, to thereby discriminate whether an input signal is a stereo signal or a monaural signal and to automatically carry out switching between the surround processing output. The time constant prevents switching between the stereo surround processing state and the monaural surround processing state from being suddenly conducted.

Abstract: An output circuit of a stereo type audio device includes a switch state detection switch which responds to an open state of a normally closed internal switch of an output jack of a first channel to separate a stereo signal source from the first and a second channels of the stereo device and connect a monoral signal source to the second channel.

Abstract: A noise component is extracted either from FM-detected output or from the so-called signal meter in the intermediate frequency amplifier. The noise component is amplified and rectified to provide a d-c signal indicative of the noise level. The rectified noise is then shaped to produce a control signal having a predetermined level and a width. The control signal is supplied to the gate circuit to control the opening and closing of the gate through which the FM detected output passes. The gate is closed during a period when the pulse noise is superimposed on the FM detected output, and is opened during a period when the pulse noise is not superimposed to the FM detected output. In the mean time, the rectified d-c signal is smoothed out to be used as a control signal for controlling the stereo separation, the attenuation of high frequency component of the MPX-demodulated audio outputs, and the overall signal level of the audio outputs.

Abstract: Stereo receiver circuit for processing a multiplex signal comprising a pilot signal by means of a pilot signal detector which detects frequency components in the multiplex signal at the frequency of the pilot signal and which controls a Schmitt trigger for influencing the mono/stereo operation, said circuit also comprising a control circuit capturing the noise components in the multiplex signal and acting on the Schmitt trigger. To prevent the Schmitt trigger from switching between the state for mono operation and the state for stereo operation in the case of weak reception field strengths, the control circuit is only active in mono operation and influences the input signal of the Schmitt trigger in the case of reception of sufficiently strong noise components to such an extent that the Schmitt trigger remains in its switching state for mono operation.

Abstract: Arrangement for decoding a stereo multiplex signal, having a baseband stero signal (L+R), a stereo difference signal (L-R) which is amplitude-modulated on a suppressed sub-carrier, and a pilot signal having a frequency located between the frequency bands of the two signals, the arrangement having an input for the stereo multiplex signal and left and right stereo signal outputs, the input being coupled both, via a pilot selection circuit, to a phase-locked loop for regenerating the sub-carrier and to a multiplier circuit for multiplying at least the modulated stereo difference signal by the regenerated sub-carrier. In order to improve the stereo channel separation, the pilot selection circuit includes a bandpass filter of the switched capacitor type, a clock input of which is coupled to an output of an voltage-controlled oscillator incorporated in the loop.