Showing papers on "Microphone published in 1982"

Wireless telephone extension unit with self-contained dipole antenna

Abstract: A remote unit for use in a wireless extension telephone system having a self-contained dipole antenna. Utilizing the unique construction of the telephone instrument housing one element of the dipole is included in a planar element that functions normally to direct sound to a self-contained microphone and the other element of the antenna is a static shield used to protect components on printed circuit board included within the extension unit.

Device for the compensation of hearing impairments

Abstract: An exemplary embodiment includes a plurality of parallel signal channels coupled with a signal input transducer, such as a microphone or induction coil. Each of the signal channels includes a respective bandpass filter for selection of a different frequency band, a controlled-gain amplifier, controlled by a volume control potentiometer, circuits for non-linear signal processing, and a bandpass filter for the reduction of distortion components caused by the non-linear processing circuits. A summing amplifier combines the signal components from all channels and is connected via an amplifier to an output signal transducer. Space requirements and power consumption are reduced in such a multi-channel processing arrangement by implementing all of the filters as sampled-data analog circuits. As a result hearing aids are provided which can be worn on the head, e.g. behind the ear.

Method and apparatus for low frequency active attenuation.

Abstract: A low frequency attenuation method based on the virtual earth system has the driver feeding cancelling waveforms into a partially closed volume which contains the microphone of the virtual earth feed-back loop. The volume preferably has a maximum dimensions which lies between one third and one seventh of the wavelength of the highest frequency to be nulled. An outlet port of the volume can be tuned to the center frequency of the band of frequencies to be nulled.

Functional Organization of the Auditory Cortex

Abstract: The properties of an acoustic signal produced by an animal can be studied by examining the output of a microphone displayed on the screen of an oscilloscope. Such an examination, however, gives us only limited information about the signal properties, so that the signal is usually analyzed with a spectrum analyzer. The spectrum analyzer has many filters tuned to different frequencies and it expresses the output of each as a function of time. Therefore, the properties of the acoustic signals are expressed by a pattern that appears in three coordinates: frequency, amplitude and time. To recognize individual acoustic patterns with an instrument, information-bearing elements (elements characterizing the signal) are first extracted and then their combinations are examined. The question next arises: how are acoustic signals analyzed and processed in the auditory system?

Method and apparatus for active sound control

Abstract: Sound control systems which employ sound cancellation may deteriorate due to ageing or change of conditions. The system described is contructed to change according to the sound level at a point where cancellation is to be achieved by sound from a loudspeaker driven by modified signals from a microphone which picks up sounds from a noise source. The signals from the microphone pass through a filter circuit having a transfer function which is controlled by a controller. Signals from the point where cancellation is required, and after modification, from the microphone and the filter circuit are employed by the controller to derive a control signal for the filter circuit.

Sound actuated microphone system

Abstract: A microphone channel is constructed from a pair of unidirectional microphone elements mounted back-to-back for monitoring sound coming from a predetermined area of space. The output signals of each microphone element are converted to D.C. logarithmic signals which are compared for gating an electrical output signal of a microphone element to the output/amplifying system.

Microphone with stepped response

Abstract: A microphone, particularly for hearing aid application, said microphone providing a stepped response characteristic relative to frequency wherein low frequency sounds will couple to the associated hearing aid with a restricted amount of amplification, while providing an emphasis or higher amplification for the higher frequencies in the bandwidth of interest.

Telephone answering and message recording system

Abstract: A telephone answering and message recording system comprises a microphone (4), an analog-digital converter (6) for converting the analog speech signal of the microphone (4) to a digital signal, a digital memory (M 1 , M 2 , M 3 , M 4 , MEM,-MEM n ) for storing the digital speech signal from the converter (6), a digital-analog converter (7) for re-converting the digital signal of the output of the memory to an analog signal, and a speaker (5) coupled to the output of the digital-analog converter (7). The system also comprises a PB (push button) code receiver (40) for detecting a PB code which is the combination of two frequencies. The operational mode and/or the memory to record or reproduce speech is switched by the particular PB code. The system may operate in a first, fixed answering, mode in which a fixed answer recorded in the memory is transmitted to a remote subscriber or in a second, adaptive oral communication, mode in which speech recorded in the memory can be revised and/or transmitted to a remote subscriber through a telephone line. In the latter mode, two remote persons may communicate with each other through the system even when those two persons do not call the system simultaneously.

Sound actuated light switch

Abstract: A sound actuated switch including a microphone coupled via an audio amplifier to a reset circuit. When a sound of sufficient intensity is received by the microphone a reset signal is supplied to the counter portion of an oscillator and counter circuit. The counter then begins counting oscillations and produces an "on" control signal until a predetermined count is reached, at which time an "off" control signal is produced. The control signal is supplied to the gate of a switching triac in a switch circuit. The presence of the on control signal causes the switching triac to electrically connect an AC power source to a load, typically a light. A simple, high efficiency DC power supply is also disclosed.

Directable microphone system

Abstract: A microphone arrangement focuses on a prescribed volume in a large room such as an auditorium. The arrangement includes a plurality of directable beam microphone structures. Each beam is directed to a prescribed location. The signals produced in the microphone structures are selectively adjusted to accept sounds from a predetermined volume surrounding the location and to reject sounds outside the prescribed volume.

Single-pulse photoacoustic technique for measuring IR multiphoton absorption by polyatomic molecules.

Abstract: The single-pulse photoacoustic technique was used to measure cross sections for IR multiphoton absorption. A discussion of this technique and the applicable pressure range is given. The source of the signals from the microphone was identified. The first peak is proportional to the energy absorbed by the gas in the focal region, while the subsequently arriving signals correspond to a mixture of the signal from the entrance and exit volumes and the ringings of the microphone and the gas cell.

Speakerphone with wireless infrared microphone

Abstract: A speakerphone instrument is disclosed having a remote microphone unit providing infrared radiation carrier transmission of voice to a base station coupled to a telephone line. Voice controlled switching of the infrared carrier may be utilized to reduce power consumption. A local microphone in the base station is operable during periods when the remote microphone unit is not transmitting or if the signal-to-noise ratio of the infrared carrier becomes unsatisfactory for voice communication, to pick-up ambient sound and make available a microphone signal for transmission over the telephone line.

Fan speed and/or fan failure detector

Abstract: A pressure transducer, such as a microphone, is placed in proximity to the blades of a fan, such as a fan used to cool electronic equipment. As each blade passes the transducer, a pressure wave is generated that is converted into an electrical pulse by the transducer. Circuitry responsive to those pulses signals an alarm if the fan is not operating properly.

Automatic sound volume control device

Abstract: An automatic volume control device for a car stereo or the like which adjusts the volume according to an environmental noise level includes a microphone and a low pass filter circuit whose characteristic is designed so as to correspond to the human auditory characteristic at a low frequency end, but so as to cut out higher frequency components such as voices, etc. A time constant circuit serves to smooth volume transients in case the environmental noise sharply increases.

Behind-the-ear type hearing aid

Abstract: A behind-the-ear type hearing aid which includes a main body adapted to hang on the user's earlobe on the rear side, an opening disposed at the front end of the main body to communicate with a microphone used for normal conversation, and a pair openings disposed on its rear end portion to communicate with a closed talking microphone for use with telephone conversations disposed in the main body. The close talking microphone may be connected to a low-pass filter with a cutoff frequency of about 1,000 hertz. The close talking microphone may also include two pressure type microphones which are substantially identical in sensitivity and are disposed adjacent to each other. One of those microphones has an output connected to that of the other microphone through a phase inverter with or without a gain control connected across the phase inverter.

Method and apparatus for locating pipeline damage

Abstract: Apparatus and method are provided for the location of pipeline damage and medium leak therefrom by acoustical monitoring of the soil about a pipe and recording emission noise by microphone and an amplifier which controls a peak noise indicator. Each measurement point detected by the amplifier is applied to a digital memory to display a histogram showing noise distribution along the pipe. The main frequency of the loudest measurement point is determined, and an octave filter is utilized to determine the frequency characterizing medium leakage to precisely locate the pipeline damage. Bar diagrams may be provided on a viewplate by bands of parallel arrays of light emitting diodes to display noise distribution along the pipeline. A frequency analyzer may transmit from the amplifier to the memory the peak frequency value of each observed frequency band to enable frequency analysis of the loudest measurement point. The apparatus may have a case with a lid defining openings sized for viewing the bar diagrams.

Echo canceller for attenuating acoustic echo signals on a frequency divisional manner

Abstract: For use in combination with a loudspeaker and at least one microphone, for example, by attendants in an auditorium, an echo cancelling circuit comprises a self-adaptive echo canceller responsive to a lower frequency component, such as below 17 kHz, of a receive-in signal for self-adatively cancelling a corresponding component of a reverberation signal included in a send-in signal during each interval during which an audio signal reaches the circuit from a remote party For a higher frequency reverberation signal component, an echo suppressor or a voice switch may reduce a weaker one of two signals which are either the higher frequency send-in and receive-in signal components or a combination of a reverberation component cancelled signal with the higher frequency send-in signal component and the whole receive-in signal Alternatively, a less expensive echo canceller non-adaptively cancels a part of the reverberation signal in response to the receive-in signal The lower frequency component of the partially reverberation cancelled signal is used by the self-adaptive echo canceller as the lower frequency send-in signal component An acoustic output may once be reproduced by the loudspeaker in response to the receive-in signal and then converted to an electric signal for supply to the echo cancelling circuit

Electroacoustic transducer of the piezoelectric polymer type

Abstract: In a piezoelectric microphone or hydrophone, the elastic structure which reacts directly to the acoustic pressure is formed of piezoelectric polymer. The electroacoustic transducer according to the invention makes use of an elastic structure in the form of a rim clamped plate having at least one incurvation and covered on at least one of its two faces with electrodes connected to an impedance-matching circuit.

Investigation of continuously traversing microphone system for mode measurement

Abstract: The continuously Traversing Microphone System consists of a data acquisition and processing method for obtaining the modal coefficients of the discrete, coherent acoustic field in a fan inlet duct. The system would be used in fan rigs or full scale engine installations where present measurement methods, because of the excessive number of microphones and long test times required, are not feasible. The purpose of the investigation reported here was to develop a method for defining modal structure by means of a continuously traversing microphone system and to perform an evaluation of the method, based upon analytical studies and computer simulated tests. A variety of system parameters were examined, and the effects of deviations from ideal were explored. Effects of traverse speed, digitizing rate, run time, roundoff error, calibration errors, and random noise background level were determined. For constant fan operating speed, the sensitivity of the method to normal errors and deviations was determined to be acceptable. Good recovery of mode coefficients was attainable. Fluctuating fan speed conditions received special attention, and it was concluded that by employing suitable time delay procedures, satisfactory information on mode coefficients can be obtained under realistic conditions. A plan for further development involving fan rig tests was prepared.

Audio feedback suppressor

Abstract: Positive feedback of an acoustic signal from a loud speaker to a microphone of a loud speaker system, i.e., howling, is prevented by randomly phase shifting an electric signal containing audio information supplied to the speaker. The random phase shifting is provided by variably delaying the electric signal in a serial analog register having a shift rate determined by an output signal of a pseudo random code generator.

Jam detecting device for copying machine

Abstract: PURPOSE:To make the whole of the device small-sized, by providing a microphone near a form carrying path and comparing the loudness and the length of sounds obtained by this microphone with reference those to detect the occurrence of a jam. CONSTITUTION:Sounds caused by running of a form along a prescribed path are converted to an electric signal by a microphone 6 and have noise components eliminated by a filter 9 and are compared with a reference level signal from a reference level setter 10 in a level detector 11; and only when the output of the filter 9 is higher than the reference level, a shaped pulse is outputted. This output pulse signal is compared with a reference pulse signal from a reference pulse width setter 12 in a pulse width detector 13; and only when the output pulse signal has a pulse width longer than that of the reference pulse signal, a jam signal 14 is outputted.

Loudspeaker telephone system

Abstract: A loudspeaker telephone system is comprised of a voice switching circuit, hybrid, and power supply circuit. The voice switching circuit includes comparators for comparing speech through the main paths with a side tone through auxiliary paths, time constant circuits for controlling exponentially a pair of variable gain amplifiers for making or breaking the sending and receiving signals, and band pass filters arranged in each input of the comparators for rejecting indoor noise as well as the line noise coming into the loudspeaker telephone system through the lines. Accordingly, the howling effect between microphone and loudspeaker is negligible; transfer from a sending mode to a receiving mode is easily made while maintaining naturalness of the voice. By inclusion of impedance matching elements in a conventional hybrid, the hybrid can be used in common either in the present loudspeaker telephone system or in a conventional telephone system. In the loudspeaker telephone system, line current is used as a bias voltage by the power supply circuit; there is no need for providing an additional power supply source.

Window shade mounted alarm system

Abstract: A home alarm system for mounting on a retractable window shade includes a display for summoning outside help in an emergency situation. The system includes a sound sensor, such as a microphone, for detecting audible noises in a room of the home and for generating electrical signals in response thereto. A driver circuit is responsive to the electrical signals generated by the microphone for actuating a visual display only when a predetermined sound, such as the alarm signal from a conventional fire, smoke, or intruder alarm, is detected. The visual display is attached to the outwardly facing surface of the window shade such that it can be viewed from outside the home. The display can be formed with any small or flexible device capable of being rolled up with the window shade during periods of nonuse. Types of display disclosed include light emitting diodes, liquid crystal displays, and electro-luminescent strips.

Multipurpose headphone assembly

Abstract: A multipurpose electronic assembly for a headphone assembly used in connection with a stereophonic system, such system comprising detection and signal means to ascertain noises extraneous to the stereophonic output system. Such assembly comprises a pick-up microphone in one or more speaker assembly for such ambient sound pick-up. The pick-up microphone is connected to an automatically actuated switch which closes whenever the pick-up microphone detects certain ambient sounds extraneous to the system. The latter automated switch assembly is directly interconnected with a voice compressor assembly, and then directly to an amplifier to provide minimal amplification of such extraneous sounds.

Fluctuating pressure measuring apparatus with miniature, high temperature, pressure transducer

Abstract: A probe (P) capable of sensing acoustic and hydrodynamic pressures in a heated flow field and an associated apparatus for acoustically exciting the heat flow (35), for positioning the probe (P) within the flow field and fro acquiring data. The probe (P) consists of a miniature microphone (10) mounted in an assembly which provides direct water cooling to the microphone body and which, by means of a bullet nosed extension (23, 24) with lateral ports (25), protects the microphone element (10) from direct impingement of the flow (35). Acoustic excitation of the flow (35) is introduced upstream of the nozzle (34) through a tube (37) from an externally mounted acoustic driver (36) which responds to the amplified output of a signal generator (38); the signal generator (38) and the amplifier (39) are adjusted to control the frequency and amplitude of the excitation. A traversing mechanism (32), capable of movement in three orthogonal directions is used to position the probe (P) within the flow (35). Signals from an acoustic excitation sensor (47) and from the probe (P) are amplified to convenient levels and processed by a two-channel Fast Fourier analyzer (40) which produces the transfer function correlograms and spectra of the input signal individually and jointly displayed on a recorder/indicator (41).

Free standing transmitting microphone

Abstract: A free standing transmitting microphone comprising a hollow holder for enclosing a transmitter and a microphone on a base. A cover of conductive material above the holder functions as an antenna for the transmitter. An acoustic pathway between the holder and the cover directs sounds to the microphone.

Comparison of stimuli used in sound field audiometric testing

Abstract: The problems associated with performing pure‐tone threshold measurements in reverberant or diffuse sound fields are illustrated with the use of three‐dimensional representations of the sound field within a typical test booth. A microphone mounted on a motorized trolley is used to perform these measurements. A comprehensive comparison is then made of the efficiency with which FM tones, AM tones, damped wave trains, and narrow bands of noise provide a uniform sound field. The conclusion is reached that the bandwidth of the stimulus is the major factor determining the uniformity of the field. A decision about the most appropriate stimulus for sound field work must thus be based on factors other than field uniformity. When the constraints of obtaining suitable spectral distributions, and being able to relate thresholds obtained with complex stimuli to those obtained with pure tones are also considered, FM tones and suitably generated narrow bands of noise appear to be the most suitable stimuli. The selection of suitable parameters is discussed and an Appendix discusses the spectrum and bandwidth of FM signals with different modulation waveforms. The relative accuracy of testing in the direct and reverberant regions in a nonanechoic environment is also discussed.

Microphone for stereo reception

Abstract: A microphone for receiving acoustic vents stereophonically in accordance with a center-side method comprises a plurality of transducers including at least one having a unilateral directional characteristic particularly cardioid or hypercardioid and at least two other electroacoustic transducers having a figure-eight characteristic which are associated with the unidirectional characteristic transducer and have principal axes at right angles to the main axes of the unidirectional transducer. A common line connects a terminal of each of the three transducers and a connecting line interconnects a respective terminal of each. In addition, the connecting line between the two electroacoustic transducers having a figure-eight characteristic include control means comprising either a switch or a controller.