Abstract: An active noise reduction earbud includes a housing and a first feedforward microphone disposed in the housing. A first sound inlet opening extends through the housing and is configured to conduct external sound to the first feedforward microphone. The first sound inlet opening is configured to sit within a concha cavum of a user's ear and faces toward an auricle of the user's ear when the earbud is worn.

Abstract: An active noise reduction earbud includes a housing and a first feedforward microphone disposed in the housing. A first sound inlet opening extends through the housing and is configured to conduct external sound to the first feedforward microphone. The first sound inlet opening is configured to sit within a concha cavum of a user's ear and faces toward an auricle of the user's ear when the earbud is worn.

Abstract: An active noise reduction earbud includes a housing and a first feedforward microphone disposed in the housing. A first sound inlet opening extends through the housing and is configured to conduct external sound to the first feedforward microphone. The first sound inlet opening is configured to sit within a concha cavum of a user's ear and faces toward an auricle of the user's ear when the earbud is worn.

Abstract: An active noise reduction earbud and method. The earbud includes a housing comprising an outlet portion that defines a sound outlet, wherein the outlet portion is configured to be located in or proximate the external auditory meatus of a user's ear, a first feedforward microphone configured to develop a first input signal, and a first sound inlet opening in the housing and configured to conduct external sound to be sensed by the first feedforward microphone, wherein the first sound inlet opening is proximate the outlet portion.

Abstract: An active noise reduction earbud and method. The earbud includes a housing comprising an outlet portion that defines a sound outlet, wherein the outlet portion is configured to be located in or proximate the external auditory meatus of a user's ear, a first feedforward microphone configured to develop a first input signal, and a first sound inlet opening in the housing and configured to conduct external sound to be sensed by the first feedforward microphone, wherein the first sound inlet opening is proximate the outlet portion.

Abstract: This application describes methods and apparatus for distributed fiber optic sensing that reduce or compensate for the effects of laser phase noise. The method involves repeatedly interrogating an optical fiber (101), where each interrogation involves launching at least one interrogating pulse into the optical fiber; detecting optical radiation which is backscattered from within the fiber, and forming a measurement signal from a plurality of sensing portions of the fiber. The method involves forming a laser noise template based on the measurement signals within a frequency band of interest from a first set of said sensing portions; and applying a correction to the measurement signals from said plurality of sensing portions based on said laser noise template.

Abstract: The technology described in this document can be embodied in a computer-implemented method that includes receiving a first plurality of values representing a set of current coefficients of an adaptive filter disposed in an active noise cancellation system. The method also includes computing a second plurality of values each of which represents an instantaneous difference between a current coefficient and a corresponding preceding coefficient of the adaptive filter, and estimating, based on the second plurality of values, one or more instantaneous magnitudes of a transfer function that represents an effect of a secondary path of the active noise cancellation system. The method further includes updating the first plurality of values based on estimates of the one or more instantaneous magnitudes to generate a set of updated coefficients for the adaptive filter, and programming the adaptive filter with the set of updated coefficients.

Abstract: The technology described in this document can be embodied in a computer-implemented method that includes receiving a first plurality of values representing a set of current coefficients of an adaptive filter disposed in an active noise cancellation system. The method also includes computing a second plurality of values each of which represents an instantaneous difference between a current coefficient and a corresponding preceding coefficient of the adaptive filter, and estimating, based on the second plurality of values, one or more instantaneous magnitudes of a transfer function that represents an effect of a secondary path of the active noise cancellation system.

Abstract: This application describes methods and apparatus for distributed fibre optic sensing that reduce or compensate for the effects of laser phase noise. The method involves repeatedly interrogating an optical fibre (101), where each interrogation involves launching at least one interrogating pulse into the optical fibre; detecting optical radiation which is backscattered from within the fibre, and forming a measurement signal from a plurality of sensing portions of the fibre. The method involves forming a laser noise template based on the measurement signals within a frequency band of interest from a first set of said sensing portions; and applying a correction to the measurement signals from said plurality of sensing portions based on said laser noise template.