In some embodiments, a method, apparatus and computer program for reducing noise from an audio signal captured by a drone (e.g., canceling the noise signature of a drone from the audio signal) using a model of noise emitted by the drone's propulsion system set, where the propulsion system set includes one or more propulsion systems, each of the propulsion systems including an electric motor, and wherein the noise reduction is performed in response to voltage data indicative of instantaneous voltage supplied to each electric motor of the propulsion system set. In some other embodiments, a method, apparatus and computer program for generating a noise model by determining the noise signature of at least one drone based upon a database of noise signals corresponding to at least one propulsion system and canceling the noise signature of the drone in an audio signal based upon the noise model.

A noise cancelling headset includes first and second earpieces, each earpiece including a respective feedback microphone, a respective feed-forward microphone, and a respective output driver. A first feedback filter receives an input from at least the first feedback microphone and produces a first filtered feedback signal. A first feed-forward filter receives an input from at least the first feed-forward microphone and produces a first filtered feed-forward signal. A first summer combines the first filtered feedback signal and the first filtered feed-forward signal and produces a first output signal. An output interface provides the first output signal as an output from the headset.

A noise cancelling headset includes first and second earpieces, each earpiece including a respective feedback microphone, a respective feed-forward microphone, and a respective output driver. A first feedback filter receives an input from at least the first feedback microphone and produces a first filtered feedback signal. A first feed-forward filter receives an input from at least the first feed-forward microphone and produces a first filtered feed-forward signal. A first summer combines the first filtered feedback signal and the first filtered feed-forward signal and produces a first output signal. An output interface provides the first output signal as an output from the headset.

Provided is a target sound extraction technique based on a steering vector generation method enabling instability in a calculation to be prevented when a neural network is trained by using an error back propagation method to reduce an estimation error of a beamformer. A target sound signal generation apparatus generates a target sound signal y.sub.t,f corresponding to a target sound included in an observed sound from an observed signal vector x.sub.t,f corresponding to the observed sound collected by using a plurality of microphones. The target sound signal generation apparatus includes a mask generation unit, a steering vector generation unit, a beamformer vector generation unit, and a target sound signal generation unit. The mask generation unit is configured as a neural network trained by using an error back propagation method. The steering vector generation unit generates a steering vector h.sub.f by determining an eigenvector corresponding to a maximum eigenvalue of a predetermined matrix generated from the observed signal vector x.sub.t,f and a mask γ.sub.t,f by using a power method.

A backrest for a vehicle seat may have a backrest part, a head restraint part and an acoustic arrangement. The acoustic arrangement is arranged above the backrest part and may have at least one central loudspeaker and at least two side loudspeakers. The central loudspeaker may be built into the head restraint part and each of the at least two side loudspeakers may be arranged on a support. A vehicle seat with the backrest is also provided.

An acoustic panel is provided that includes a perforated first skin, a second skin and a core. The core is connected to the perforated first skin and the second skin. The core includes a plurality of chambers and a plurality of septums respectively arranged with the chambers. The chambers include a first chamber that extends vertically between the perforated first skin and the second skin. The septums include a first septum that extends laterally across the first chamber. The first septum includes a first septum orifice. The first septum tapers laterally inward towards the first septum orifice as the first septum extends vertically towards the second skin.

An acoustic panel is provided that includes a perforated first skin, a second skin and a core. The core is connected to the perforated first skin and the second skin. The core includes a plurality of chambers and a plurality of septums respectively arranged with the chambers. The chambers include a first chamber that extends vertically between the perforated first skin and the second skin. The septums include a first septum that extends laterally across the first chamber. The first septum includes a first septum orifice. The first septum tapers laterally inward towards the first septum orifice as the first septum extends vertically towards the second skin.

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.

Devices for preventing unintended conversation from being recorded by a voice activated assistant device/application (VAD) are disclosed. The device is contoured to fit over a functional surface of a VAD that typically includes a plurality of microphones and control buttons. The device covers the microphones and uses its own microphones to monitor for an authorization input signal. In an embodiment, the devices uses speakers aligned with and opposing each VAD microphone. The device emits interfering audible signals during this mode of operation. Once the device senses an authorization input, the device decouples its speakers from the interfering audible signal and instead allows the device microphones to pass through to the VAD. During this mode, the VAD is in normal operation.