An audio apparatus includes a touch detective muting arrangement. Switch actuating knobs made of metal are electrically insulated from the circuit ground and connected to an electro-static field detector circuit detecting a touch of an operator's finger with the knobs and producing a control signal. A muting circuit is provided in the audio signal path and connected to the detector circuit to be controlled by the control signal. When a finger touches the knob, the muting circuit is rendered oper...

A device for the viewing of photo-images and the presentation of sound recordings corresponding to such photo-images, which device may be controlled by the user to provide substantially random access to any photo-image and the sound recording corresponding thereto, is disclosed. A modular construction of such device and its adaptability to either hand-held or projection embodiments is described. A novel tone arm system as well as a novel turntable driving mechanism, a novel disc type record unit...

An audio dosimeter for determining the exposure to noise as a function of both time and noise level. Input sound energy is appropriately weighted so as to account for the effect thereof on the human ear. The weighted sound signal is then utilized to gate pulses of selected discrete frequency levels to a counter, such that as the sound level increases, correspondingly higher frequency pulses are coupled to the counter. The counter stores the count therein until read out by an appropriate display ...

An audio dosimeter for individual use determining exposure to sound energy as a function of both frequency and pressure level, with integration over the time of exposure and incorporating storage means preserving a quantitative measure of the exposure.

An audio amplifier having an auxiliary terminal for connection of a feedback line to the grounded terminal of a loudspeaker and including a circuit for protection against voltage overload on the amplifier and loudspeaker if the auxiliary terminal is inadvertently connected to the ungrounded terminal of the loudspeaker, or in case of malfunction of the feedback circuit. The protection circuit includes a signal generator activated by the closing of a power switch for circuiting a check signal thro...

An audio amplifier having an auxiliary terminal for connection of a feedback line to the grounded terminal of a loudspeaker and including a circuit for protection against voltage overload on the amplifier and loudspeaker if the auxiliary terminal is inadvertently connected to the ungrounded terminal of the loudspeaker, or in case of malfunction of the feedback circuit. The protection circuit includes a signal generator activated by the closing of a power switch for producing a check signal for c...

An audio system, characterized in that the audio signal passes through a preamplifier, equalization unit and electronic cross-over and before reaching the power amplifiers, which drive the speakers, is modified by an electronic resonance control correction (ERCC) circuit.

An amplifier for use in an audio communication circuit between a dynamic microphone and an output line. The amplifier produces a signal at the output having characteristics similar to those of a signal from a carbon microphone, i.e., noise is suppressed in the output line when no speech signal is present. The amplifier includes a main channel including two stages coupled through two arms of a T-pad. In the absence of a voice signaal from the microphone, the third arm of the T-pad is effectively ...

Audio systems using a digital audio interface between a sender and a receiver are known. Due to the digital revolution, it is very easy to make copies of copyright protected work. By using a bi-directional control bus in the audio interface, it is made possible to send audio signals with a standard quality to "normal" receivers audio, and higher quality audio to receivers which are authorized to receive higher quality audio.

An audio buffer includes one or more audio effect resources that modify audio data received from an audio data source. A first audio effect resource in the audio buffer receives audio data from the audio data source and modifies the audio data to generate a stream of audio data. Subsequent audio effect resource(s) in the audio buffer receives the stream of audio data from the first audio effect and further modifies the audio data to generate a stream of modified audio data. The stream of modifie...