A method of designing an acoustic liner includes identifying acoustic path lengths that will attenuate a frequency within a frequency range of interest, and selecting a liner configuration with a combination of acoustic paths that addresses the frequency range of interest. The selection may be made after a comparison of the response of different liner configurations.

A method and a device for controlling the propagation of acoustic waves in the vicinity of a wall, the method and device implementing a master device for controlling a set Nc of cells primarily made up of a speaker, a set of Nm microphones connected to the speaker, and a control unit, by means of control laws that determine the intensity of the electrical signal that must be sent to each speaker so as to obtain a target determined generalized acoustic impedance for each speaker, such that a fraction of the acoustic waves is absorbed by the membrane of each speaker.

A noise suppressing heat exchanger (also referred to as heat sink) includes a plurality of heat dissipating fins formed with baffles. The baffles suppress noise from a fan by slowing air flow and creating internal reflections within the heat exchanger that reflect noise away from the air flow path, absorbing sound energy and potentially setting up standing waves which dissipate noise via destructive interference. Other embodiments may be described and/or claimed.

A bone conduction speaker includes a housing, a vibration board and a transducer. The transducer is located in the housing, and the vibration board is configured to contact with skin and pass vibration. At least one sound guiding hole is set on at least one portion of the housing to guide sound wave inside the housing to the outside of the housing. The guided sound wave interfaces with the leaked sound wave, and the interfacing reduces a sound pressure level of at least a portion of the leaked sound wave. A frequency of the at least a portion of the leaked sound wave is lower than 4000 Hz.

A speaker comprises a housing, a transducer residing inside the housing, and at least one sound guiding hole located on the housing. The transducer generates vibrations. The vibrations produce a sound wave inside the housing and cause a leaked sound wave spreading outside the housing from a portion of the housing. The at least one sound guiding hole guides the sound wave inside the housing through the at least one sound guiding hole to an outside of the housing. The guided sound wave interferes with the leaked sound wave in a target region. The interference at a specific frequency relates to a distance between the at least one sound guiding hole and the portion of the housing.

A speaker comprises a housing, a transducer residing inside the housing, and at least one sound guiding hole located on the housing. The transducer generates vibrations. The vibrations produce a sound wave inside the housing and cause a leaked sound wave spreading outside the housing from a portion of the housing. The at least one sound guiding hole guides the sound wave inside the housing through the at least one sound guiding hole to an outside of the housing. The guided sound wave interferes with the leaked sound wave in a target region. The interference at a specific frequency relates to a distance between the at least one sound guiding hole and the portion of the housing.

Aspects of the present disclosure provide methods, apparatuses, and systems for closed-loop sleep protection and/or sleep regulation. According to an aspect, sleep disturbing noises are predicted and a biosignal parameter is measured to dynamically mask predicted disturbing environmental noises in the sleeping environment with active attenuation. Environmental noises in a sleeping environment of a subject are detected, input, or predicted based on historical data of the sleeping environment collected over a period of time. The biosignal parameter is used to determine sleep physiology of a subject. Based on the environmental noises in the sleeping environment and the determined sleep physiology, the noises are predicted to be disturbing or non-disturbing noises. For predicted disturbing noises, one or more actions are taken to regulate sleep and avoid sleep disruption by using sound masking prior to or concurrently with the occurrence of the predicted disturbing noises.

Aspects of the present disclosure provide methods, apparatuses, and systems for closed-loop sleep protection and/or sleep regulation. According to an aspect, sleep disturbing noises are predicted and a biosignal parameter is measured to dynamically mask predicted disturbing environmental noises in the sleeping environment with active attenuation. Environmental noises in a sleeping environment of a subject are detected, input, or predicted based on historical data of the sleeping environment collected over a period of time. The biosignal parameter is used to determine sleep physiology of a subject. Based on the environmental noises in the sleeping environment and the determined sleep physiology, the noises are predicted to be disturbing or non-disturbing noises. For predicted disturbing noises, one or more actions are taken to regulate sleep and avoid sleep disruption by using sound masking prior to or concurrently with the occurrence of the predicted disturbing noises.

An open audio device including an acoustic radiator that emits front-side acoustic radiation from its front side, and emits rear-side acoustic radiation from its rear side. A front acoustic cavity receives front-side acoustic radiation and comprises at least one front sound-emitting opening, and a rear acoustic cavity receives rear-side acoustic radiation and comprises at least one rear sound-emitting opening. The front and rear acoustic cavities each have a fundamental frequency. The fundamental frequencies are within one octave of each other.

A speaker comprises a housing, a transducer residing inside the housing, and at least one sound guiding hole located on the housing. The transducer generates vibrations. The vibrations produce a sound wave inside the housing and cause a leaked sound wave spreading outside the housing from a portion of the housing. The at least one sound guiding hole guides the sound wave inside the housing through the at least one sound guiding hole to an outside of the housing. The guided sound wave interferes with the leaked sound wave in a target region. The interference at a specific frequency relates to a distance between the at least one sound guiding hole and the portion of the housing.