Rotor noise cancellation through the use of mechanical means for a personal aerial drone vehicle. Active noise cancellation is achieved by creating an antiphase amplitude wave by modulation of the propeller blades, by utilizing embedded magnets through an electromagnetic coil encircling the propeller blades. A noise level sensor signals the rotor control system to adjust the frequency of the electromagnetic field surrounding the rotor and control the speed of the rotor. An additional method comprises of incorporating a phase lock loop within the control system configured to determine the frequencies corresponding to the rotors and generate corrective audio signals to achieve active noise cancellation.

A work machine includes a housing. The housing at least partly houses a machine. The housing has an opening. The work machine includes a path leading into the housing from the opening. The work machine includes a controller and a speaker. The controller is configured to cause a speaker to output a control sound for reducing operating noise. The operating noise is generated in the housing by motion of the machine and propagates in the path from a source of the operating noise to the opening. The speaker is arranged so that the control sound propagates in the path with its wavefront parallel to a wavefront of the operating noise that propagates in the path.

An audio controller for an active noise reduction, ANR, reduces an ambient noise signal. The audio controller includes processing circuitry configured to provide a fixed ANR filter configured to generate a first noise reduction signal. Moreover, the processing circuitry is further configured to provide an adaptive ANR filter. The adaptive ANR filter includes one or more adjustable filter coefficients for adapting the adaptive ANR filter and the adaptive ANR filter is configured to generate a second noise reduction signal. The processing circuitry is further configured to generate a total noise reduction signal as an adjustable weighted linear combination of the first noise reduction signal and the second noise reduction signal.

Various implementations include systems for processing inner microphone audio signals. In particular implementations, a system includes an external microphone configured to be acoustically coupled to an environment outside an ear canal of a user; an inner microphone configured to be acoustically coupled to an environment inside the ear canal of the user; and an adaptive noise cancelation system configured to process an internal signal captured by the inner microphone and generate a noise reduced internal signal, wherein the noise reduced internal signal is adaptively generated in response to an external signal captured by the external microphone.

Various aspects include a wearable audio device having active noise reduction (ANR), where the ANR device includes: a feedback microphone; an electroacoustic transducer; and a feedback compensator configured to output a noise reduction signal to the electroacoustic transducer in response to a feedback signal from the feedback microphone, wherein the feedback compensator includes a tunable filter that modulates a loop gain in response to an adverse low frequency event being detected in the noise reduction signal outputted from the tunable filter, wherein the tunable filter is configured to maintain a substantially similar loop gain shape near a low frequency cross-over as the low frequency cross-over changes during loop gain modulation.

A system and method for quieting unwanted sound. As a non-limiting example, various aspects of this disclosure provide a system and method, for example implemented in a premises-based or home audio system, for quieting unwanted sound at a particular location.

An unmanned flying object, capable of suppressing an increase in overall size while having a configuration to reduce noise, is provided. The unmanned flying object includes a duct that corresponds to: at least one generator that generates airflow; at least one microphone; and at least one speaker. The duct covers the at least one generator in a direction perpendicular to an airflow direction, passes the airflow in the airflow direction, includes a space between inner and outer peripheral surfaces, and defines an opening at the end of the space in the airflow direction. A shape of the inner peripheral surface is tapered in the airflow direction. The at least one microphone is positioned in the space. The at least one speaker is positioned closer to the at least one generator than the at least one microphone.

Various implementations include systems for processing inner microphone audio signals. In particular implementations, a system includes an external microphone configured to be acoustically coupled to an environment outside an car canal of a user; an inner microphone configured to be acoustically coupled to an environment inside the ear canal of the user; and an adaptive noise cancelation system configured to process an internal signal captured by the inner microphone and generate a noise reduced internal signal, wherein the noise reduced internal signal is adaptively generated in response to an external signal captured by the external microphone.

A system for reducing noise for a user includes a first detector configured to generate a first noise signal, wherein the first noise signal is a representation of a first noise that is transmitted to the user through a first sound pathway, and a second detector configured to generate a second noise signal, wherein the second noise signal indicates a second noise perceived by the user. The system also includes a processor configured to determine a noise correction signal based on the first noise signal and/or the second noise signal, and a speaker configured to generate a sound for reducing the noise based on the noise correction signal.

An active noise cancellation system has a secondary path including a loudspeaker configured to output an anti-noise signal to cancel noise in a noise cancellation zone, and an error microphone configured to sense sound in the noise cancellation zone. The ANC system further includes a logic device configured to adaptively generate the anti-noise signal for playback through the loudspeaker based at least in part on a feedback signal from the error microphone and identify a user of the active noise cancellation system based, at least in part, on a measured frequency response of the secondary path. The logic device is further configured to identify the user of the active noise cancellation system through a comparison of the measured frequency response of the secondary path to stored models and may be configured to execute a new user enrollment process, store user profiles, and/or switch between in-ear and open-air states.