Cirrus Logic Inc.

Wolfson Microelectronics Limited

Incus Laboratories Limited

Cirrus Logic International (uk) Limited

Cirrus Logic International Semiconductor Limited

Alastair Sibbald

Robert Alcock

Peter John McCutcheon

Martin Howle

Robert David Alcock

David Monteith

Peter Mccutcheon

Peter John Mccutcheon

A host device configured to be wirelessly coupled to an accessory device, the host device comprising noise reduction circuitry, wherein, in use of the host device: a signal generated by a microphone of the accessory device in response to ambient noise is supplied to the noise reduction circuitry; the noise reduction circuitry applies a noise reduction transfer function to the signal supplied thereto to generate a noise cancellation signal; and the noise cancellation signal is supplied to at least one loudspeaker of the accessory device; and wherein the noise reduction transfer function applied by the noise reduction circuitry is user selectable or user adjustable.

Communication apparatus with ambient noise reduction

A feedforward ambient noise reduction arrangement includes, within a housing, a loudspeaker device for directing sound energy into an ear of a listener. Disposed externally of the housing, and positioned to sense ambient noise on its way to the listener's ear, are plural microphone devices capable of converting the sensed ambient noise into electrical signals for application to the loudspeaker to generate an acoustic signal opposing the ambient noise. Importantly, the overall arrangement is such that the acoustic signal is generated by said loudspeaker means in substantial time alignment with the arrival of said ambient noise at the listener's ear.

Ambient noise reduction arrangements

Noise reduction circuitry for a communication apparatus can apply different noise reduction transfer functions, depending on whether a listening device is connected to the apparatus. If no listening device is connected, the noise reduction transfer function can be adapted for use with microphones and speakers that form an integral part of the communication apparatus, which may be a cellular telephone. If a listening device is connected, the noise reduction transfer function can be adapted for use with microphones and speakers that form a part of the listening device. This allows the noise reduction circuitry to provide improved noise reduction performance.

An active noise-reduction headphone arrangement has a housing bearing a loudspeaker having a first diaphragm surface coupled to a first volume of air bounded by and coupled to a user's ear, and a second diaphragm surface bounding a cavity within the housing assembly so as to define a second volume of air, rearward of the diaphragm; a conduit provided in the housing, the conduit being in fluid communication the ambient air via a first acoustic couple means having a first characteristic acoustic impedance, the conduit also being in fluid communication with said second volume of air via a second acoustic couple means having a second characteristic acoustic impedance; and a microphone having an inlet coupled acoustically to a predetermined location within the conduit.

Acoustic coupling arrangements for noise-cancelling headphones and earphones

A MEMS microphone assembly has an enclosure enclosing a volume of air. A MEMS microphone chip is provided within the enclosure. First and second acoustic ports are formed in the enclosure, defining first and second fluid paths between the volume of air and air outside the enclosure. The MEMS microphone responds to a pre-determined linear interpolative value between two independent pressure signals supplied via first and second ports according to the potentiometic ratio of the acoustic impedances of the first and second ports.

MEMS microphone assembly

The present invention relates to earphone arrangements configured to accommodate an acoustically-resistant couple within the compact dimensions of ear-bud type earphones, and aims to incorporate a front volume to rear volume acoustic couple into an earphone without requiring significant addition to the lateral dimensions of the earphone. The earphone has an elongate sound outlet port that locates into a listener's ear canal and bears an internal support surface which is apertured and communicates with the outlet port. A microspeaker is supported on the support surface and projects sound through the aperture and toward the outlet port. Furthermore, the housing includes a front cavity in front of the microspeaker and in communication with the outlet port, and a rear cavity behind the microspeaker. The support surface bears a recess that communicates with the front cavity, and an acoustic resistor is accommodated in the recess.

Earphone arrangements

Noise reduction circuitry for a communication apparatus can apply different noise reduction transfer functions, depending on whether a listening device is connected to the apparatus. If no listening device is connected, the noise reduction transfer function can be adapted for use with microphones () and speakers () that form an integral part of the communication apparatus, which may be a cellular telephone. If a listening device is connected, the noise reduction transfer function can be adapted for use with microphones () and speakers () that form a part of the listening device. This allows the noise reduction circuitry to provide improved noise reduction performance.

A noise cancellation system is provided, for generating a noise cancellation signal to be added to a wanted signal to mitigate the effects of ambient noise. The system comprises: an input, for receiving an input signal representing ambient noise; a detector, for detecting a magnitude of said input signal; and a voice activity detector, for determining voiceless periods when said input signal does not contain a signal representing a voice. The detector is adapted to detect the magnitude of said input signal during said voiceless periods, and the system is adapted to operate in a first mode when said input signal is above a threshold value, and a second mode when said input signal is below the threshold value. The first mode comprises generating a noise cancellation signal with a first magnitude for at least partially cancelling the ambient noise. The second mode comprises generating a noise cancellation signal with a second magnitude that is less than the first magnitude.

Noise cancellation system with gain control based on noise level

A feedforward ambient noise reduction arrangement () includes, within a housing, a loudspeaker device for directing sound energy into an ear of a listener. Disposed externally of the housing, and positioned to sense ambient noise on its way to the listener's ear, are plural microphone devices (-) capable of converting the sensed ambient noise into electrical signals for application to the loudspeaker to generate an acoustic signal opposing the ambient noise. Importantly, the overall arrangement is such that the acoustic signal is generated by said loudspeaker means in substantial time alignment with the arrival of said ambient noise at the listener's ear.

A signal processing circuit is intended for use in a noise reduction system, which produces a target filter characteristic that would achieve optimal noise cancellation, the target filter characteristic including a resonant peak at a first frequency. The signal processing circuit comprises an analogue filter, which has an amplitude response that has a peak or trough at a center frequency, and has a phase response that switches polarity at the center frequency and tends to zero with increase or reduction in frequency away from the center frequency. The center frequency in the amplitude response is substantially equal to the first frequency. The analogue filter may be in the form of a series inductive-capacitive-resistive circuit, where the inductive component is in the form of a gyrator.

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Cookham, United Kingdom

Alastair Sibbald