Abstract: Aspects of the subject technology relate to stiffness reduction for audio transducers, such as speakers. Stiffness reduction can be provided using one or springs disposed at least partially within a cavity in a magnet of the audio transducer. The magnet may be a center magnet, around which a voice coil of the speaker extends.

Abstract: A reactive filter assembly comprising a reactive filter acoustically coupled to a transducer operable to generate an audio frequency by air non-linearity demodulation of an ultrasonic frequency, the reactive filter having a number of acoustic pathways tuned to introduce a radiation impedance to the transducer that improves transducer efficiency.

Abstract: A transducer attenuator assembly comprising: an enclosure defining an acoustic chamber coupled to a sound output port of a transducer that is operable to generate audible frequencies from ultrasonic frequencies; and a plurality of openings formed through the enclosure to acoustically couple the acoustic chamber to a surrounding ambient environment, and the plurality of openings are arranged to attenuate an ultrasonic sound wave and leak an audible sound wave output by the transducer to the acoustic chamber.

Abstract: Aspects of the subject technology relate to monitoring one or more characteristics of a speaker, such as an excursion, rocking amplitude, or force factor of the speaker. The monitoring may be performed without the use or presence of a sensor that directly measures these speaker characteristics. The monitoring may include determining the excursion, rocking amplitude, or force factor based on an intermodulation distortion that occurs when an ultrasonic tone and one or more human audible tones are output by the speaker concurrently, and/or based on a phase difference between peaks in a speaker current and a speaker voltage.

Abstract: Aspects of the subject technology relate to monitoring one or more characteristics of a speaker, such as an excursion, rocking amplitude, or force factor of the speaker. The monitoring may be performed without the use or presence of a sensor that directly measures these speaker characteristics. The monitoring may include determining the excursion, rocking amplitude, or force factor based on an intermodulation distortion that occurs when an ultrasonic tone and one or more human audible tones are output by the speaker concurrently, and/or based on a phase difference between peaks in a speaker current and a speaker voltage.

Abstract: A transducer assembly comprising: an air motion transformer having a magnet assembly operable to provide a magnetic field and a folded diaphragm having conductive traces and operable to expand or contract in a first direction and emit a sound in a second direction perpendicular to the first direction; and a ferromagnetic assembly comprising a number of fixed members arranged within folds of the folded diaphragm to provide a closed loop magnetic circuit that drives the expansion or contraction of the folded diaphragm.

Abstract: Aspects of the subject technology relate to electronic devices having speakers such as microelectromechanical systems (MEMS) speakers. A MEMS speaker can include an electrostatically driven, corrugated MEMS structure to move air without a magnet, coil, or traditional speaker membrane, and thus provide a low-power, compact speaker with a large acoustically active area in a small volume. Neighboring folds in the corrugated MEMS structure may form pairs of MEMS electrodes that can be pushed together and/or pulled apart to deform the MEMS structure in a breathing motion that generates pressure differentials on opposing sides of the corrugated MEMS structure to generate sound. Additional modes of operation are described.

Abstract: A microelectromechanical transducer assembly comprising: an enclosure defining an interior chamber and an opening from the interior chamber to a surrounding ambient environment; a first sound radiating member operable to produce a first frequency; and a second sound radiating member arranged parallel to the first radiating member and operable to produce a second frequency that in combination with the first frequency generates an audible sound output.

Abstract: A transducer assembly comprising: a frame positioned within an interior chamber defined by an enclosure comprising a port to an ambient environment; a surround comprising a fixed portion sealed to the frame and a movable portion dividing the interior chamber into a front volume chamber coupling a first side of the surround to the port and a back volume chamber coupled to a second side of the surround; and a barometric vent coupled to the fixed portion to vent a pressure between the front volume chamber and the back volume chamber.

Abstract: A portable electronic device comprising: an enclosure having an enclosure wall that defines a first chamber, a second chamber and an acoustic opening from the first chamber or the second chamber; and an electroosmotic flow valve operable to open and close the acoustic opening.

Abstract: A transducer assembly comprising: a frame positioned within an interior chamber defined by an enclosure comprising a port to an ambient environment; a surround comprising a fixed portion sealed to the frame and a movable portion dividing the interior chamber into a front volume chamber coupling a first side of the surround to the port and a back volume chamber coupled to a second side of the surround; and a barometric vent coupled to the fixed portion to vent a pressure between the front volume chamber and the back volume chamber.

Abstract: An electro-acoustic transducer has an acoustic diaphragm and a voice-coil. The diaphragm defines a first major surface. A flange extends from the diaphragm in a direction opposite the first major surface. The voice-coil has a first plurality of windings positioned adjacent to the acoustic diaphragm and a second plurality of windings positioned distally from the acoustic diaphragm. The flange overlaps the first plurality of windings. The flange and the windings can be adhesively bonded with each other to form a lap joint. The lap joint can transfer force from the voice-coil to the diaphragm.

Abstract: Aspects of the subject technology relate to a shaker module for an electronic device. The shaker module may include a movable component that is resiliently suspended in relation to a voice coil by one or more gap-separated pairs of the flat springs. The flat springs reduce the z-height of the shaker module for implementation in, for example, compact electronic devices. The gap-separated pairs of flat springs facilitate adjustment of the resonance frequency of the shaker module substantially independently of adjustments to drop performance, while providing stability against unwanted rocking motions of the movable component.

Abstract: A moving magnet motor comprising: a stationary voice coil coupled to a frame; a moving magnet assembly movably coupled to the frame and operable to move relative to the stationary coil, the moving magnet assembly comprising a magnet and a flux concentrating member that define a gap within which the stationary coil is positioned; and an actuating surface coupled to the moving magnet assembly, and wherein a movement of the moving magnet assembly drives a movement of the actuating surface along an axis of translation.

Abstract: A transducer assembly comprising: an air motion transformer having a magnet assembly operable to provide a magnetic field and a folded diaphragm having conductive traces and operable to expand or contract in a first direction and emit a sound in a second direction perpendicular to the first direction; and a ferromagnetic assembly comprising a number of fixed members arranged within folds of the folded diaphragm to provide a closed loop magnetic circuit that drives the expansion or contraction of the folded diaphragm.

Abstract: A transducer assembly comprising: a magnet motor assembly comprising a first magnet plate and a second magnet plate arranged along an axis, a first support plate positioned between inward facing surfaces of the first magnet plate and the second magnet plate, a second support plate positioned along an outward facing surface of the first magnet plate to form a first magnetic gap between the first support plate and the second support plate, and a third support plate positioned along an outward facing surface of the second magnet plate to form a second magnetic gap between the first support plate and the third support plate; a voice coil coupled to the magnet motor assembly, wherein the voice coil is positioned around the first support plate and within the first magnetic gap and the second magnetic gap; and a piston coupled to the voice coil, wherein the piston is operable to vibrate in a direction parallel to the axis.

Abstract: Aspects of the subject technology relate to electronic devices having speakers such as microelectromechanical systems (MEMS) speakers. A MEMS speaker can include an electrostatically driven, corrugated MEMS structure to move air without a magnet, coil, or traditional speaker membrane, and thus provide a low-power, compact speaker with a large acoustically active area in a small volume. Neighboring folds in the corrugated MEMS structure may form pairs of MEMS electrodes that can be pushed together and/or pulled apart to deform the MEMS structure in a breathing motion that generates pressure differentials on opposing sides of the corrugated MEMS structure to generate sound. Additional modes of operation are described.

Abstract: Aspects of the subject technology relate to electronic devices having speakers such as microelectromechanical systems (MEMS) speakers. A MEMS speaker can include cylindrical corrugated MEMS structure. The cylindrical corrugated MEMS structure may include a contiguous MEMS structure with corrugations that run around an open cylindrical core that is defined, in part, by interior folds of the corrugations. The cylindrical corrugated MEMS structure may be deformed, responsive to an applied voltage, such that a portion of the cylindrical corrugated MEMS structure bends into and/or out of the open cylindrical core to push air out of and/or pull air into the open cylindrical core. In one or more implementations, a MEMS speaker may include an array of cylindrical corrugated MEMS structures.

Abstract: An electronic device can include a housing defining an aperture and a display positioned in the aperture. The display and the housing can define an internal volume in which a speaker assembly is positioned. The speaker assembly can include a speaker module and a speaker enclosure in fluid communication, with the speaker enclosure at least partially defining a speaker volume.

Abstract: A loudspeaker having a compressible lead wire is described. The lead wire carries an electrical audio input signal to a voice coil. The electrical audio input signal drives the voice coil to oscillate in an axial direction. The compressible lead wire includes an elastic portion that stretches and compresses in the axial direction to allow the voice coil to oscillate freely. The elastic portion includes several compressible elements that are located within a cavity of the loudspeaker. The compressible elements extend through the cavity in the axial direction. Other aspects are also described and claimed.