Noise cancellation apparatus
First Claim
1. A transducer for use in a noise cancellation apparatus for reducing background noise comprising:
- a housing having first microphone means for receiving a first acoustic sound composed of speech originating from an operator operating said apparatus and background noise, and for converting said first acoustic sound to a first signal, and second microphone means arranged at a predetermined angle .O slashed. in close proximity with respect to said first microphone means for receiving a second acoustic sound composed of substantially said background noise and for converting said second acoustic sound to a second signal;
said first and second microphones are connected to a differential amplifier means of the noise cancellation apparatus so as to obtain a signal representing substantially speech;
the amplifier means for receiving acoustic sounds from each microphone and having a first terminal and a second terminal, wherein the second terminal is grounded;
a transistor means for receiving and amplifying an AC signal representative of the audio input from each microphone; and
means for filtering the amplified AC signal from the DC signal, so that the DC signal powers the amplifier means.
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Accused Products
Abstract
Disclosed is a transducer for use in a noise cancellation apparatus for reducing background noise. The transducer includes a housing having first microphone means for receiving a first acoustic sound composed of speech originating from an operator operating the apparatus and background noise, and for converting the first acoustic sound to a first signal, and second microphone means arranged at a predetermined angle φ in close proximity with respect to the first microphone means for receiving a second acoustic sound composed of substantially the background noise and for converting the second acoustic sound to a second signal. The first and second microphones are connected to a differential amplifier means of the noise cancellation apparatus so as to obtain a signal representing substantially speech. The amplifier means is for receiving acoustic sounds from each microphone and has a first terminal and a second terminal, wherein the second terminal is grounded. The transducer further includes a transistor means for receiving and amplifying an AC signal representative of the audio input from each microphone; and means for filtering the amplified AC signal from the DC signal, so that the DC signal powers the amplifier means. Also disclosed is a method for calibrating an active noise reduction apparatus including a housing having a speaker to produce an acoustic anti-noise signal in the housing, a microphone to detect an external noise signal, and an amplitude adjustment means to calibrate the acoustic anti-noise signal to create a quiet zone in the housing for operation with an independent electrical assembly, wherein the apparatus is calibrated separately from the electrical assembly. The method includes the steps of: inputting the external noise signal received by the microphone to produce an anti-noise signal; transmitting to the speaker the anti-noise signal having an equal gain and opposite phase response to the external noise signal detected by the microphone; and balancing the gain and phase response of the anti-noise signal by the amplitude adjustment means located in the noise reduction apparatus to match the gain and phase response of the external noise signal to yield a theoretical zero in the quiet zone.
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Citations
23 Claims
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1. A transducer for use in a noise cancellation apparatus for reducing background noise comprising:
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a housing having first microphone means for receiving a first acoustic sound composed of speech originating from an operator operating said apparatus and background noise, and for converting said first acoustic sound to a first signal, and second microphone means arranged at a predetermined angle .O slashed. in close proximity with respect to said first microphone means for receiving a second acoustic sound composed of substantially said background noise and for converting said second acoustic sound to a second signal; said first and second microphones are connected to a differential amplifier means of the noise cancellation apparatus so as to obtain a signal representing substantially speech; the amplifier means for receiving acoustic sounds from each microphone and having a first terminal and a second terminal, wherein the second terminal is grounded; a transistor means for receiving and amplifying an AC signal representative of the audio input from each microphone; and means for filtering the amplified AC signal from the DC signal, so that the DC signal powers the amplifier means. - View Dependent Claims (2, 3)
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4. An active noise reduction apparatus for reducing ambient noise in the vicinity of an eardrum, comprising:
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a housing for receiving an input audio signal; an output transducer located in the housing; an input transducer for detecting and reducing ambient noise, the input transducer not located in substantially the same plane as the output transducer; signal processing means to reduce the ambient noise detected by the input transducer; an acoustic means including an acoustic waveguide for transmitting the input audio signal to the eardrum without disturbance of the ambient noise and having low pass filter characteristics with a zero phase shift over a desired bandwidth to isolate the output transducer from the input transducer for channeling the input audio signal representing substantial speech between the output transducer and the eardrum, wherein a quiet zone is created to isolate sound transmitted from the input transducer. - View Dependent Claims (5)
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6. An active noise reduction apparatus comprising:
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a housing having an earphone; microphone means mounted in the earphone facing towards an ear of a user for detecting unwanted ambient noise; means to convert the noise to electric signals; phase shifting and attenuation means connected to the microphone to provide an inverted anti-noise signal; an output transducer substantially out of plane with the microphone means for transmitting the audio signal to the user'"'"'s ear; means for preventing mechanical vibration induced low frequency disturbances from being transmitted to the output transducer; an acoustic waveguide isolating the microphone means from the output transducer for creating a quiet zone in close proximity to the output transducer and thereby excluding the unwanted ambient noise from reaching the user'"'"'s ear.
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7. An active noise reduction apparatus for use in a headset with a boom microphone to reduce ambient noise from reaching a user'"'"'s ear without disturbing a desired audio signal outputted to the listening ear comprising an earphone located within the headset;
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a pick-up microphone for detecting noise signals within the earphone facing towards the ear; means for converting the noise signals into electric signals; electro-acoustic means for applying the electric signals to the earphone to produce acoustic signals 180°
degrees out of phase with the ambient noise;an output transducer means mounted in the earphone having an acoustical filter having low pass filter characteristics with a zero shift phase over a desired bandwidth for coupling speech to the user'"'"'s ear and isolating vibration induced low frequency disturbances from reaching the user'"'"'s ear.
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8. A noise reduction system for use with an active noise cancellation apparatus comprising:
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a pick-up microphone located in the headset for detecting noise signals to convert to electrical signals; a speaker located in the headset having a acoustic means with low pass filter characteristics with a zero phase shift over a desired bandwidth; an audio transmission signal; means for electrically rejecting vibrations of the electrical signal; a variable gain/control means for inverting the noise signal to produce an anti noise-signal; the acoustic means for filtering out mechanical vibration induced low frequency disturbances from reaching the speaker; acoustic summing means to combine the anti-noise signal and the noise signal to produce a quiet zone in the acoustic means; means for transmitting the audio signal to the speaker; and means for maintaining phase agreement between the noise signal and the anti-noise signal of the speaker. - View Dependent Claims (9, 10, 11, 12)
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13. An active noise reduction apparatus for reducing ambient noise in the vicinity of an eardrum, comprising:
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a housing for receiving an input audio signal; an output transducer located in the housing; an input transducer located in the housing for detecting ambient noise located in the housing; a signal processing means to process noise detected by the input transducer; an acoustic means for channeling the input audio signal representing substantial speech between the output transducer and the eardrum; and
an acoustic waveguide means for transmitting the input audio signal without disturbance of the noise to the eardrum creating a quiet zone to isolate sound transmitted from the input transducer.
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14. A method for calibrating an active noise reduction apparatus including a housing comprising a speaker to produce an acoustic anti-noise signal in the housing, a microphone to detect an external noise signal, and an amplitude adjustment means to calibrate the acoustic anti-noise signal to create a quiet zone in the housing for operation with an independent electrical assembly, wherein the apparatus is calibrated separately from the electrical assembly, the method comprising the steps of:
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inputting the external noise signal received by the microphone to produce an anti-noise signal; transmitting to the speaker the anti-noise signal having an equal gain and opposite phase response to the external noise signal detected by the microphone; and balancing the gain and phase response of the anti-noise signal by the amplitude adjustment means located in the noise reduction apparatus to match the gain and phase response of the external noise signal to yield a theoretical zero in the quiet zone. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification