An audio dosimeter for use by an individual for measuring exposure to sound which contains the following components: (a) an electronic microphonic sound sensor means, (b) an amplifier and weighting circuit, (c) an x-squared detector circuit, (d) a temperature compensation circuit; (e) analog to digital time converter, (f) a microcomputer which controls functions of the temperature compensator circuit and analog to digital time converter and has unique logarithmic mathematics for converting the s...

An amplifier circuit for a speaker 12. The circuit includes an operational amplifier 16 connected to a supply rail 24 and a supply rail 26 through a regulator 28 and a regulator 30. The circuit is characterized by a P channel MOS-FET 32 having a source 34 connected to the rail 24 and a drain 36 connected to the speaker 12 and a gate 38, and an N channel MOS-FET 40 having a source 42 connected to the rail 26 and a drain 44 connected to the speaker 12 and a gate 46. A NPN stage 48 is responsive to...

An audio apparatus includes a signal generating circuit for generating a first electrical audio frequency signal corresponding to audio information received from a source, such as a phonograph turntable, tape recorder or FM/AM tuner. A loudspeaker generates an acoustic signal in response to the first audio frequency signal, and a microphone pick-up receives the acoustic signal for generating a corresponding second electrical audio frequency signal. A filter network then separates the first and s...

An audio amplifier connected to the secondary winding of a transformer. The primary winding of the transformer is connected in a series with a triac to a conventional power source, such as a 60 hertz, 115 to 120 volt source of alternating current. The triac is turned on at a predetermined time during the latter portion of each half cycle to cause a current pulse to be transmitted through the primary winding. To make the triac non-conductive to terminate each pulse, there is provided a bypass cir...

A method and apparatus are disclosed for scrambling and descrambling an audio signal. An interference signal is generated and is intermittently, preferably pseudo-randomly, added to the program audio as a function of control information generated either by means of hardware alone or by means of software. The scrambled audio and the interference signal are preferably transmitted on two carriers, e.g., two standard subcarriers used in TV broadcasting, together with the control information. A decod...

The input stage to an audio amplifier comprises a complementary-symmetry, differential amplifier pair which drives an intermediate voltage gain stage comprised of a complementary-symmetry, cascode differential amplifier pair. The intermediate stage provides signal drive and bias to the output power amplifier stage, which is preferably a bridged configuration. Control circuitry produces a composite bias signal which is the summation of a static bias signal and a dynamic bias signal. The bias cont...

A control unit for controlling operation of a plurality of audio teleconference terminals comprises a plurality of inputs which are connected each to a particular terminal. A speech detector detects from which terminals speech signals are received and actuates switching means to connect those terminals in open loop teleconference.

An audio buffer includes one or more audio effects that modify audio data received from an audio data source. A first audio effect 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 effects 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 modified audio data is then routed f...

An audio cable formed of a mass of wires which are wound together into a first group and a second group, the wires of the first group are electrically connected together by the wires being coated with an electrically conductive material such as a tin alloy. The wires of the first group are to facilitate the conducting of low frequency audio signals. The wires of the second group are electrically insulated relative to each other with each wire being coated with an electrically insulating material...

An audio amplifier has a collapsible power supply coupled to an audio amplifier circuit to drive voltage rails of the power supply in an inverse relationship to the power consumed by the amplifier circuit. A variable gain input stage includes a linear potentiometer gain control followed by a gain stage and buffer to drive separate bass and treble controls, summed before appearing at the input of an integrated circuit amplifier. The main voltage amplification is provided by an integrated circuit,...