This disclosure includes several different features suitable for use in circumaural and supra-aural headphones designs. Designs that include earpad assemblies that improve acoustic isolation are discussed. User convenience features that include automatically detecting the orientation of the headphones on a user's head are also discussed. Various power-saving features, design features, sensor configurations and user comfort features are also discussed.

An autonomous cleaning device and a noise reduction air duct device are provided for autonomous cleaning device. The autonomous cleaning device includes a body and a motor arranged on the body, and the noise reduction air duct device is mounted on the body. The noise reduction air duct device includes an upper housing, a lower housing and a support noise reduction structure made of elastic material. The lower housing and the upper housing enclose to form an air duct, an air inlet is arranged at a position of the air duct corresponding to the motor, and an air outlet is arranged on a side of the air duct away from the air inlet; the support noise reduction structure has a first end fixed on the lower housing, and a second end abutting against a lower surface of the upper housing.

A face mask can both actively cancel sounds and passively attenuate sounds spoken by the user to prevent the sounds from reaching non-intended recipients positioned near the user. The mask can not only reduce the user's voice from escaping the mask but can also be used to reduce external sounds from reaching inside the mask. Thus, a user can wear the mask in public and talk on their phone without disturbing others around them. The mask can include at least one microphone and at least one audio speaker disposed inside and/or outside the mask. Sounds received by the microphone can be processed by a microphone and computing electronics to provide an output to the audio speaker that can appropriately attenuate the sound received by the microphone, via acoustic cancelation. The mask can not only be used to cancel sounds but may also be used to amplify sounds when desired.

A reference microphone for detecting noise is located under a first duct. The noise is in the form of a first plane wave in the first duct. A speaker is located on a top of the first duct. Connected to an upper part of the first duct is a second duct including an error microphone. The first plane wave in the first duct passes through an acoustic path and reaches the second duct. The error microphone detects the sound, and the speaker outputs a second plane wave with an opposite phase for canceling the first plane wave.

A hybrid ANC system that can allow a feedback microphone to receive the same external noise as a feedforward microphone. A processor can generate an anti-noise signal based on what both microphones received to cancel a broader range of frequencies of the external noise.

An audio enhanced hearing protection system to be worn by a user includes an ambient noise reduction assembly having a primary noise reduction unit and a secondary noise reduction unit. The audio enhanced hearing protection system also includes an audio input assembly having one or more environmental microphones to receive raw environmental audio signals. The raw audio signals are transformed into processed audio signals via a digital signal processing assembly prior to transmission to a user. The audio enhanced hearing protection system also includes an audio output assembly having at least one speaker to transmit processed audio signals to a user.

A body dryer includes an airflow generator to generate a flow of air, an inlet to pass air from the surroundings to the airflow generator, an outlet to vent the air from the airflow generator, a body, and a movable bar, the bar supported by the body. A drive assembly is provided between the body and the bar, the bar movably driven relative to the body. A noise cancellation device is provided to cancel or reduce noise in at least one of the airflow generator and the drive assembly.

A work machine includes microphones inside the housing. The microphones are configured to collect sound inside the housing, and output sound signals that are electrical signals corresponding to the collected sound. The sound includes an operating noise generated inside the housing due to motion of a machine. The microphones are arranged at different locations inside the housing. The work machine is configured to execute a process related to the operating noise based on the sound signals from the microphones.

A refuse vehicle includes a body coupled at least one of the frame and the chassis, a battery configured to provide electrical power to a first motor, a vehicle body supported by the chassis and defining a receptacle for storing refuse therein, an electric power take-off system coupled to the vehicle body, the electric power take-off system including a second motor configured to convert electrical power received from the battery into hydraulic power, one or more microphones coupled to the body and configured to detect noise, one or more speakers coupled to the body configured to emit noise reducing sounds, and a controller configured to receive data related to the detected noise from the one or more microphones and cause the one or more speakers to emit the noise reducing sounds in response to the data received from the one or more microphones.

The work machine includes a path leading into a housing from an opening. The path is provided to control an airflow generated by motion of a machine. The work machine includes a microphone. The microphone is configured to collect sound in the housing, including operating noise generated in the housing by the motion of the machine. The work machine further includes a structure that defines a receiving space for the microphone along the path through which the operating noise propagates outside the housing. The structure includes an open structure that connects the receiving space with the path and faces downstream in the path. The structure surrounds the receiving space upstream of the open structure in the path.