Abstract: The electronic stethoscope is designed to minimize the influence of the various types of noise while optimizing auscultation of the sounds of interest, and to enable a cardiologist to auscultate mechanical heart valves. It comprises a probe for sensing sounds of interest produced within a patient's body and for converting these sounds to an electric signal, and an audio amplifier and earphones for reproducing the sounds of interest in response to this electric signal.

Abstract: A microelectronic circuit featuring techniques for further miniaturization having particular interest for devices such as hearing aids characterized as having four sections: one section containing "normal use" circuits, a second section having "special use" circuits, a third section for "control"; and a fourth section containing passive components which are generally physically large. The "normal use" section contains those circuits that are in use most of the time. For hearing aids this would include, e.g., programmable audio response circuits. The "special use" circuits are those circuits that are in use for only a short period of time. For hearing aids, this would include a memory for storing the user's hearing loss prescription. The control circuit includes circuits for switching the large passive elements of the fourth section back and forth between the "normal use" sections and the "special use" sections.

Abstract: A circuit in which, when loudspeakers are being used by themselves, the equalization to the loudspeakers is optimized for full range operation and only the intended filters for full range operation are inserted into the circuit path. When a subwoofer is added to the system to handle low frequencies, the subwoofer mating connector is inserted into a connector jack to receive the audio signals and simultaneously inserts high pass filters into the circuit for the speakers so they operate in the mid range and high frequency range where they are better suited. The subwoofer handles and reproduces the low frequencies. The result is louder and clearer satellite speakers that exhibit a much lower tendency to clip the signals from the amplifier driving them.

Abstract: In an audio signal output device, when muting audio signals outputted from audio signal output terminals, a ground terminal provided for the audio signal output terminals is brought into an open state in association with the muting action, so that the audio signals can be adequately muted without causing any noise or the like.

Abstract: A consumer appliance having both explanatory comment and extra-linguistic signalization upon actuation thereof and reversible stepping between those two.An electronics-controlled consumer appliance has various hardwared actuator elements for through actuation thereof driving the appliance from a present state to an associated respective destination state. It also has audio output for under control of selected present state-actuation combinations outputting a specific audio specifier. By way of improvement the specifier comes in a two-tier organization: in an upper tier it outputs an explanatory audio comment and in a lower tier it outputs an extra-linguistic audio signalization. Furthermore, the device allows for selectively and reversibly stepping between said two tiers.

Abstract: An audio mixer system using a serial editor interface is disclosed. Use of a microprocessor control circuit is disclosed to control various functions a plurality of multiple channel VTRs under the control of a mixer. Serial control signals are supplied from a video editor to a serial interface which includes a microprocessor. These control signals are decoded, and the appropriate controls of the VTRs are implemented. These controls include crossfading as well as PREVIEW/REVIEW monitoring.

Abstract: A dispatching console system (20) for handling communications transmissions includes a main processor (50) and a co-processor (52). The main processor (50) receives external console control commands which specify a desired settable (i.e., connect/disconnect) relationship between audio devices in communication with the console and issues main processor commands to the co-processor (52). The co-processor (52) controls a switching circuit (72) in an audio tower (24). The switching circuit (72) is a matrix of cross-point switches (220) which connects and disconnects selected communication devices. In addition to the main processor commands, desired settable relationships between audio devices can also be mandated by device activation input signals which are applied through the audio tower (24) to the co-processor (52).

Abstract: A circuit for controlling on-off switching of an audio amplifier in such a manner as to prevent sharp uncontrolled variations of the output during switching from resulting in undesired noise (popping) on the loudspeakers. For so doing, the circuit provides for generating a controlled positive potential at the negative input in relation to the positive input of the amplifier when this is switched on or off. More specifically, when switching on, the potential difference is maintained pending switching of all the sources on the amplifier, after which, it is gradually eliminated for enabling the output to reach the steady-state value slowly and in controlled manner; whereas, when switching off, the potential difference is generated gradually for enabling the output of the amplifier to be grounded slowly prior to turning off the amplifier itself.

Abstract: A two channel audio switcher includes two analog switches, which may be implemented as a CMOS integrated circuit, receiving at their control input ports a complementary pair of drive signals, typically square wave, so as to toggle their outputs at a supersonic rate, which may be made variable. The switcher may receive as input two channels of a stereophonic source, two independent audio sources or a common monophonic source. The outputs typically drive an audio output unit such as the transmitter of a radio broadcasting system, an audio recording system, or amplifiers, controls and loudspeakers of a sound reinforcement system in an auditorium or studio. The system may be monophonic or stereophonic. In a stereophonic a.m. broadcasting system such as the Kahn independent sideband system, alternate switching allows each sideband to be modulated to full available power, thus allowing an increase in the apparent radiated power.

Abstract: An active sound reproducer (76, 78) receives an audio signal and setting signals (volume settings, filter coefficients) via a digital bus (75) for processing the audio signal. Normally, the setting signals are applied by a suitable ("compatible") control unit (74). If this unit is not present, this task is taken over by one sound reproducer operating as a "master". In a setup procedure, it is determined which one of the sound reproducers operates as a master. Each sound reproducer is adapted to receive remote control signals and to transmit these signals to the master reproducer via the digital bus. This master reproducer then distributes the setting signals to the relevant sound reproducers via the digital bus. The control unit or the reproducer operating as a master may be located in another space.

Abstract: A semiconductor integrated circuit includes a first circuit and a second circuit. The first circuit is set into an operative state in a first mode and into a non-operative state in a second mode, and the transfer characteristic thereof depends on an externally attached impedance circuit. The second circuit is set into an operative state in the second mode and into a non-operative state in the first mode. A resistor is externally connected to the second circuit. A third circuit for keeping a voltage applied across the resistor constant and deriving a current flowing in the resistor in the first mode irrespective of the presence or absence and the magnitude of a voltage applied to one end of the resistor is provided in the first circuit. The resistor is commonly used by the first circuit and the second circuit.

Abstract: An output transducer and amplifier are shared between an audio system and a cellular Phone in an automotive vehicle. An interface arbitrates between the program audio signals and the phone audio signals to select or deselect each of the audio signals depending on the status of each audio source. When only one source is in use then normally the audio signals from that source are selected. If both sources are turned on but a phone call is not in progress, then audio signals from both sources are simultaneously presented to the output transducers after summing. When a call is in progress, only the phone audio signals are selected.

Abstract: An audio mixer system for use with a parallel editor interface is disclosed. Use of a configuration selector to select a desired configuration of a plurality of multichannel devices is disclosed in order to enable such various configurations and reconfigurations. In one embodiment, the output of the configuration selector is provided to a memory to select prestored commands to be provided to appropriate channels. According to another embodiment, the configuration selection signals are decoded and supplied to multiplexers in combination with editor control signals to enable the editor control signals to be routed to appropriate channels.

Abstract: A volume control circuit in a system including a tuner and a deck which are prepared as separate components and combined together. The tuner has a control purpose audio input terminal, an audio output terminal, and an audio output level variable circuit provided between the control purpose audio input terminal and the audio output terminal. The tuner further includes a controller for setting the gain of the audio output level variable circuit. The deck has an audio output terminal connected to the control purpose audio input terminal of the tuner so as to issue an audio signal from the audio output terminal of the tuner. The controller of the tuner controls the gain of the audio output level variable circuit to vary the output volume.

Abstract: A surround system comprising front, center, and rear amplifiers which respectively drive front, center and rear speaker units. The system operates in a surround sound environment with low impedance (4.OMEGA.) speaker units. When high impedance speaker units are connected, the system automatically cuts the center and rear speaker units and operates in a non-surround sound environment by the front amplifier only. Accordingly, the system does not require a excessive large power supply unit.

Abstract: An audio system for use with a mobile radio. More particularly, a microprocessor controlled audio system capable accepting multiple audio input signals and providing an amplified audio signal to a local speaker and a remote speaker without the use of transformers or relays, and capable of driving the speakers either individually or simultaneously. The system provides for increased versatility in output configurations, and allows for microprocessor-controlled muting and power output level switching.

Abstract: A mixed simulcast circuit in which the voice signal demodulated in the voice demodulator through the tuner and the voice signal from the outside can be recorded on the recording medium according to the user's desire, then reproduced selectively. The mixed simulcast circuit has first means for recording a signal which is received in the tuner and demodulated in the demodulator, second means for recording the modulated voice signal on the one channel of the recording medium and for recording the voice signal from the external on the other channel thereof, and means for switching selectively one signal, either the voice signal which is demodulated and recorded from tuner or the voice signal, which is recorded from the external, when it reproduced.

Abstract: An output stage for a multitimbral electronic musical instrument providing automatic detection of the use of submix outputs is provided. The present invention allows the use of effects processors on selected timbres without the need for user intervention when the effects are connected or removed. The present invention also allows for use of such processors without an external mixboard.

Abstract: Separate audio amplifier channels are provided with separate input signal level controls so that the output of one channel is unaffected by the input signal level of the other channel, and vice versa. A switch controls selection of the desired channel. Three channels also be provided and first and second switches control selection of any one of the three channels. As before, separate input signal level controls are provided for the three channels so that each is unaffected by the signal level control of either of the others. Two channels may be distortion channels, each with an input level control and also with an output level control. One channel may be a clean sound channel.

Abstract: A circuit electrically connecting a single pair of speakers to a radio speaker output of a radio and to a tape deck speaker output of a tape deck through relay contacts in a manner whereby in a first position of the contacts the radio speaker output is electrically connected to the speakers and the tape deck speaker output is disconnected from the speakers, and in a second position of the contacts the tape deck speaker output is electrically connected to the speakers and the radio speaker output is disconnected from the speakers. A relay energizing winding controls the positioning of the relay contacts. A current-sensitive switch is electrically connected to the relay energizing winding and to the tape deck power supply and is electrically connected to the radio power supply when the contact means is in its first position.

Abstract: A hearing aid includes an electronic amplifier, an electric power source and a switch for automatically breaking or making the connection between the amplifier and the power source depending on whether the hearing aid is in use or out of use. The switch is provided in such a manner so as to be responsive to switching criterion defined by a change of state such as change in temperature, moisture etc. The switch is disposed at a wall surface which is subjected to the change of state.

Abstract: A driving apparatus for driving an electro-acoustic transducer comprises a power amplifier for supplying a drive power to the transducer, and a feedback circuit for generating a negative impedance. The feedback circuit has a main body portion connected to the amplifier and a control information storage body for storing control information for setting transmission characteristics of the feedback circuit. The storage body is arranged to be disconnected/connected to the main body portion. The main body portion comprises a plurality of transducer connection terminals connected to a plurality of transducers, respectively, a plurality of relays and normally-open contacts for selectively supplying an amplifier output to the transducer connection terminals. A transducer selection information is housed in the control information storage body.

Abstract: Separate audio amplifier channels are provided with separate input signal level controls so that the output of one channel is unaffected by the the input signal level of the other channel, and vice versa. A switch controls selection of the desired channel. Three channels may also be provided and first and second switches control selection of any one of the three channels. As before, separate input signal level controls are provided for the three channels so that each is unaffected by the signal level control of either of the others. Two channels may be distortion channels, each with an input level control and also with an output level control. One channel may be a clean sound channel.

Abstract: An audio production console has a plurality of input modules connected between an input and a common output bus. The modules are identical, and contain a plurality of circuits for carrying out functions on a signal from the corresponding input. A central control unit is connected to each of the modules and controls selected circuits of the units, to control the operation of the module. In this way the functions carried out by the modules are freely selectable, and hence the switching of circuits within each module may be simplified. This enables the normal separate monitor section of an audio production console to be omitted from each module, simplifying the module and the operation of the console as a whole.

Abstract: An equalizer quick switch is provided which provides a switching interface between multichannel input signal sources, an equalizer, and a multichannel amplifier with multiple inputs. In one embodiment the switching is performed by manually operated switches. In another embodiment, the switching is performed automatically when the input sources are switched on. This is accomplished using current sensing on the input power mains, and a logic switch matrix employing either buffers and inverters or, alternatively, a diode switching matrix.

Abstract: A recording disk data playback apparatus capable of playback of recording disks having digitized audio data recorded thereon and disks having audio data recorded in analog form, by FM modulation, as well as disks having both digital and analog forms of audio data recorded thereon (together with video data), is provided with a switching circuit for selecting digital audio signals to be supplied to left and right channel output terminals respectively with the switching configuration being designed to minimize crosstalk, and a switching circuit whereby either digital audio signals or analog-derived audio signals can be selected to be supplied to a single pair of (left and right channel) output terminals.

Abstract: A speaker changeover device has a plurality of audio equipments for outputting ready condition signals when the power source is turned on; a speaker which is used by the audio equipments in common, a changeover control circuit which starts its operation by turning a cycle start switch, cyclically monitors the ready condition signals from the audio equipments simultaneously with the input of clock signals and generates a changeover signal to the audio equipment which first outputs the ready condition signal to stop its operation, and an electromagnetic relay operated by the changeover signal to connect the audio equipment which first outputs the ready condition signal, to the speaker.

Abstract: There is provided in a car-mounted audio system an operator control section, a display section and a mechanical deck section in a central console or dashboard unit, wherein other units are located in hideaway positions, the system being characterized in that, a built-in microphone and a microphone amplifier are provided at the central control apparatus, buffers are provided at the hideaway units, and a microphone signal bus line is incorporated in the signal line connection between the central control and the hideaway units to couple a common microphone output signal therebetween.

Abstract: An apparatus for integrating a plurality of audio systems, for enabling a selected one of a plurality of audio inputs to be transmitted as an audio output. It is adapted to integrate, for example, a stereo sound system and a telephone sound system, so as to be operable from a control panel adapted to be mounted in the wall of a bathtub or the like.The apparatus is adapted to enable elements of the integrated system to be shared in common by a plurality of audio inputs, so as to generate a selected audio output.The apparatus includes a voltage-controlled amplifier, for controlling the selected audio input signal with a direct-current control voltage. It further includes a plurality of parallel circuits, for generating the direct-current control voltage, one such circuit for each of the plurality of audio inputs, and elements for switching from one such circuit to another.

Abstract: An audio/video recording and reproducing system having a discrete function unit such as tape deck, record player or tuner connected thereto includes a function selection circuit and a function specifying switch disposed in a main unit, such as a pre/main amplifier, and a control line, such as remote control line, for connecting the main unit and the discrete unit. By virtue of the function selection circuit, the selection of a desired discrete function unit can be carried out at the main unit. However, in addition to this, the system includes an arrangement for permitting selection of a desired discrete function unit at the discrete function unit itself, and, when this is done, for controlling the function selection at the main unit to select the output of the discrete function unit.

Abstract: A method and a system for rapidly attaining a large number of different sounds in an audio signal processing system. A preferred embodiment comprises an audio signal processing system which includes a main housing, containing a main circuit apparatus, cartridge-receiving recesses, and cartridges fabricated to be removably received in the recesses, each cartridge containing an audio effects circuit which affects the signal in a unique way to provide a different sound output. A plurality of electrical contacts of the recess and cartridge respectively provide disengageable connection of the audio effects circuit to the system.

Abstract: A method and a system of organizing, arranging and rearranging, the number and sequential order of audio effects circuit modules, by the changing, including inserting, removing, exchanging and interchanging, of said modules, providing noiseless, uninterrupted signal flow through a system during each of said changing operations. A preferred embodiment of the method comprises an audio signal processing system which includes a main housing, containing a main circuit apparatus, module-receiving recesses, and modules, fabricated to be received in the recesses, each module having an electronic circuit which affects the signal in a unique way to provide a different sound output. A plurality of switches and potentiometers lie on the main housing, and each module has markings indicating which controls on the main housing are to serve its operation.

Abstract: A method and a system of organizing, arranging and rear-ranging the number and sequential order of audio effects circuit modules by the changing, including inserting, removing, exchanging and interchanging, of said modules providing noiseless, uninterrupted signal flow through a system during each of said changing operations. A preferred embodiment of the method comprises an audio signal processing system which includes a main housing, containing a main circuit apparatus, module-receiving recesses, and modules, fabricated to be received in the recesses, each module having an electronic audio effect circuit which affects the signal in a unique way to provide a different sound output. A plurality of switches and potentiometers lie on either the main housing or the module, and each module has markings indicating which controls are to serve its operation.

Abstract: A stereo speaker mixer is disclosed for coupling a plurality of pairs of stereo speakers to the output of an amplifier. A plurality of manually operable selection switches is provided for selecting and coupling in parallel a particular number of speaker pairs. The position of the these switches is detected and decoded by digital logic circuitry which is utilized to couple an appropriate value impedance matching device between the amplifier and the selected number of speaker pairs in response to the actual number of speaker pairs selected. A safety circuit is provided which ensures that at least one pair of speakers is always coupled to the amplifier output without regard to the position of the selection switches, thereby preventing the sudden and unexpected application of amplifier output to a speaker pair.

Abstract: In an exemplary embodiment, switches are provided for controlling operating state, and the like, of a miniature hearing aid. In such hearing aids, it is a precondition that all components, thus the switches as well, be designed very small and function reliably. Therefore, the disclosure provides magnetic switches which exhibit elements whose electrical conductivity can be influenced with magnetic fields. For example, reed contacts or magnetic field responsive semiconductors are employed as such elements. Thus, manual switching can ensue by means of displacing a magnet. Magnetically actuatable switches, however, can also serve to automatically switch on an auxiliary element, for instance a device for improving the reception of a telephone call (induction coil), when a magnetic field present outside of the device, for instance the magnetic field of a telephone receiver, approaches. A hearing aid equipped according to the disclosure is particularly suited for use in conjunction with induction coils.

Abstract: In a tape reproducing apparatus combined with a radio set having a tape reproducing circuit, a radio reception circuit and a loudspeaker, an apparatus capable of connecting a headphone to one of the tape reproducing circuit and the radio reception circuit when the other circuit is connected to the loudspeaker.

Abstract: A power control circuit (22) for selectively supplying power from a constantly available power source (20) to an amplified speaker (12) by sensing the existence of an audio signal in a differential stage by determining the differential potential signal between leads (16, 18) to produce a ground reference signal which is amplified by a transistor (28) and thereafter rectified (52) to provide a direct current signal which operates a relay driver transistor (42) which, in turn, operates a relay switch (46) to supply power to the speaker amplifier (14). The discontinuance of power to the speaker amplifier is delayed for a period of time after the discontinuance of the audio signal to the differential stage (24) by placing a capacitor (58) between the rectifier and the relay driver transistor (42) to power the relay driver transistor for a period of time after the audio signal is no longer being provided.

Abstract: To provide both for soft-switching, that is, elimination of switching clicks, and rapid rise and decay of tone supply from a frequency generator (10) to an audio transducer (13), two electronic switches (11, 16) are provided, one interrupting connection from the source to an audio amplifier amplifying the signals for the transducer, and the other (16) effectively short-circuiting the amplifier, the switches having current transfer/time characteristics to provide for gradual current rise and current decay through the amplifier, and hence gradual rise and drop of the level of output from the transducer with sufficiently steep flanks, however, to effectively eliminate harmonics and hence high-frequency switching clicks. Typical switches use opto couplers with an instantaneous ON optical element such as a light emitting diode (30, 36) illuminating a photo resistor (31, 37) which has resistance change vs. time characteristics following an exponential function.

Abstract: Automobile radio - cassette combination which includes a special announcement decoder, for example to decode traffic announcements and the like. To shield passengers in an automotive vehicle from additionally listening to announcements, while permitting passengers to continue to listen to recorded programs on a tape, for example, while permitting the operator to listen to traffic announcements, the switching network of the radio with the announcement feature is expanded, and coupled with a selector switch permitting, selectively, operation of:(a) earphone reproducing cassette; loudspeaker muted, automatic announcement reproduction maintained;(b) earphones reproduce radio program, loudspeaker muted, automatic announcement reproduction via loudspeaker maintained;(c) earphone reproduces cassette, loudspeaker reproduces radio program, including announcements;(d) loudspeaker reproduces cassette program, radio muted.