Direction-aware active noise cancellation system
First Claim
1. A method for reducing an acoustic energy level at a listening position, the method comprising:
- receiving a primary acoustic wave at a first reference position to form a first reference signal;
receiving the primary acoustic wave at a second reference position to form a second reference signal;
separating each of the first reference signal and the second reference signal into a plurality of sub-band signals in the frequency domain;
determining, in the frequency domain, a direction of propagation of the primary acoustic wave for each sub-band of the first reference sub-band signal and each sub-band of the second reference sub-band signal based on the first and second reference sub-band signals;
forming, in the frequency domain, a feedforward sub-band signal based on the determined direction of propagation of the primary acoustic wave; and
generating a secondary acoustic wave based on the feedforward sub-band signal, the secondary acoustic wave adapted to reduce the acoustic energy level at the listening position.
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Abstract
Robust feedforward active noise cancellation is provided which can overcome or substantially alleviate problems associated with the diverse and dynamic nature of the surrounding acoustic environment. A multi-faceted analysis is performed to determine the direction (or directions) of propagation of noise in the surrounding acoustic environment. The direction of propagation is then utilized to determine direction-dependent characteristics of the acoustic path between a reference position where the noise is captured and a desired position where the noise is to be cancelled. These characteristics are used to form a feedforward signal adapted to cancel the noise at the desired position. By forming the feedforward signal based on direction-dependent characteristics of the acoustic path, the techniques described herein can achieve optimal noise cancellation at the desired location, regardless of the direction of propagation of the noise.
29 Citations
20 Claims
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1. A method for reducing an acoustic energy level at a listening position, the method comprising:
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receiving a primary acoustic wave at a first reference position to form a first reference signal; receiving the primary acoustic wave at a second reference position to form a second reference signal; separating each of the first reference signal and the second reference signal into a plurality of sub-band signals in the frequency domain; determining, in the frequency domain, a direction of propagation of the primary acoustic wave for each sub-band of the first reference sub-band signal and each sub-band of the second reference sub-band signal based on the first and second reference sub-band signals; forming, in the frequency domain, a feedforward sub-band signal based on the determined direction of propagation of the primary acoustic wave; and generating a secondary acoustic wave based on the feedforward sub-band signal, the secondary acoustic wave adapted to reduce the acoustic energy level at the listening position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for reducing an acoustic energy level at a listening position, the system comprising:
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a first reference microphone for receiving a primary acoustic wave at a first reference position to form a first reference signal, receiving the primary acoustic wave comprising converting the primary acoustic wave to a frequency-domain such that the first reference signal is separated into sub-bands in the frequency domain; a second reference microphone for receiving the primary acoustic wave at a second reference position to form a second reference signal, receiving the primary acoustic wave comprising converting the primary acoustic wave to a frequency-domain such that the second reference signal is separated into sub-bands in the frequency domain; a feedforward module for determining, in the frequency domain, a direction of propagation of the primary acoustic wave for each sub-band of the first reference signal and each sub-band of the second reference signal based on the first and second reference signals, and to form, in the frequency domain, a feedforward sub-band signal based on the determined direction of propagation of the primary acoustic wave; and an audio transducer for generating a secondary acoustic wave based on the feedforward sub-band signal, the secondary acoustic wave adapted to reduce the acoustic energy level at the listening position. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A non-transitory computer readable storage medium having embodied thereon a program, the program being executable by a processor to perform a method for reducing an acoustic energy level at a listening position, the method comprising:
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receiving a primary acoustic wave at a first reference position to form a first reference signal; receiving the primary acoustic wave at a second reference position to form a second reference signal; separating each of the first reference signal and the second reference signal into a plurality of sub-band signals in the frequency domain; determining, in the frequency domain, a direction of propagation of the primary acoustic wave for each sub-band of the first reference signal and each sub-band of the second reference signal based on the first and second reference signals; forming, in the frequency domain, a feedforward sub-band signal based on the determined direction of propagation of the primary acoustic wave; and generating a secondary acoustic wave based on the feedforward sub-band signal, the secondary acoustic wave adapted to reduce the acoustic energy level at the listening position. - View Dependent Claims (19, 20)
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Specification