AMBIENT NOISE REDUCTION SYSTEM
First Claim
1. An adaptive feed-forward system for reducing ambient noise perceived by a listener to an ear-proximal speaker-carrying device, the system comprisinga reference microphone means for sensing ambient noise approaching the device and for providing first electrical signals representative of the noise sensed thereby;
- a connection path conveying said first electrical signals to a speaker of the device;
inverting means in said connection path for inverting said first electrical signals;
an adaptive electronic filter means in said connection path; and
a control means for adjusting one or more characteristics of said filter means in response to said first electrical signal, wherein said adaptive filter means is constrained to always conform to one of a predetermined family of filter responses, and thereby to operate within a predetermined and limited set of amplitude and phase characteristics.
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Accused Products
Abstract
An adaptive, feed-forward, ambient noise-reduction system includes a reference microphone for generating first electrical signals representing incoming ambient noise, and a connection path including a circuit for inverting these signals and applying them to a loudspeaker directed into the ear of a user. The system also includes an error microphone for generating second electrical signals representative of sound (including that generated by the loudspeaker in response to the inverted first electrical signals) approaching the user'"'"'s ear. An adaptive electronic filter is provided in the connection path, together with a controller for automatically adjusting one or more characteristics of the filter in response to the first and second electrical signals. The system is configured to constrain the operation of the adaptive filter such that it always conforms to one of a predetermined family of filter responses, thereby restricting the filter to operation within a predetermined and limited set of amplitude and phase characteristics.
221 Citations
31 Claims
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1. An adaptive feed-forward system for reducing ambient noise perceived by a listener to an ear-proximal speaker-carrying device, the system comprising
a reference microphone means for sensing ambient noise approaching the device and for providing first electrical signals representative of the noise sensed thereby; -
a connection path conveying said first electrical signals to a speaker of the device; inverting means in said connection path for inverting said first electrical signals; an adaptive electronic filter means in said connection path; and a control means for adjusting one or more characteristics of said filter means in response to said first electrical signal, wherein said adaptive filter means is constrained to always conform to one of a predetermined family of filter responses, and thereby to operate within a predetermined and limited set of amplitude and phase characteristics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 23)
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22. (canceled)
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24. An adaptive feed-forward system for reducing ambient noise perceived by a listener to an ear-proximal speaker-carrying device, the system comprising:
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a reference microphone means for sensing ambient noise approaching the device and for providing first electrical signals representative of the noise sensed thereby; a connection path conveying said first electrical signals to a speaker of the device, means in said connection path for inverting said first electrical signals; an adaptive electronic filter means in said connection path, said adaptive filter means having a plurality of possible filter responses, each of said possible filter responses corresponding to a respective amount of acoustic leakage past the device within a predetermined range; an error microphone means for sensing sounds approaching the ear canal of the listener and for providing second electrical signals representative of the sounds sensed thereby, said sounds including noise generated by the speaker of the device in response to the inverted and filtered first electrical signals conveyed thereto over said connection path; and a control means for selecting one of said possible filter responses in response to said first and second electrical signals. - View Dependent Claims (25, 26, 27)
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28. An adaptive feed-forward system for reducing ambient noise perceived by a listener to an ear-proximal speaker-carrying device, the system comprising:
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a reference microphone for sensing ambient noise approaching the device and for providing first electrical signals representative of the noise sensed thereby; a connection path conveying said first electrical signals to a speaker of the device;
an inverter in said connection path for inverting said first electrical signals;an error microphone for sensing sounds approaching the ear canal of the listener and for providing second electrical signals representative of the sounds sensed thereby, said sounds including noise generated by the speaker of the device in response to the inverted first electrical signals conveyed thereto over said connection path; an adaptive electronic filter in said connection path; and an adaptive controller for adjusting one or more characteristics of said adaptive electronic filter in response to said first and second electrical signals, wherein said adaptive electronic filter is constrained always to conform to one of a predetermined family of filter responses, and thereby to operate within a predetermined and limited set of amplitude and phase characteristics. - View Dependent Claims (29, 30, 31)
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Specification