A method for producing a diaphragm for an ultrasonic sensor. In the method, a diaphragm body made of metal material is first provided. Next, an external surface region of the diaphragm body is degreased. The external surface region of the diaphragm body is then pickled. To pre-activate the subsequently applied second passivation layer, a first passivation layer is also deposited on the external surface region as a first layer.

A method for producing a diaphragm for an ultrasonic sensor. In the method, a diaphragm body made of metal material is first provided. Next, an external surface region of the diaphragm body is degreased. The external surface region of the diaphragm body is then pickled. To pre-activate the subsequently applied second passivation layer, a first passivation layer is also deposited on the external surface region as a first layer.

A low-profile panel assembly configured to provide sound having at least one acoustic wavelength within a passenger compartment of a vehicle is provided. The vehicle has a support structure. The assembly includes a substrate panel perforated with at least one sub-wavelength hole which extends between front and back surfaces of the panel. The panel is configured to be attached to the support structure. A continuous membrane of facing material overlies and is in contact with the panel. The membrane is tightly stretched over and covers the at least one hole at the front surface of the panel. An electroacoustic sound source is configured to radiate acoustic waves against the back surface of the panel. The radiated acoustic waves travel through the at least one membrane-covered hole to vibrate at least one portion of the membrane which tightly covers the at least one hole. The at least one vibrating portion of the membrane radiates acoustic waves into the passenger compartment of the vehicle.

Aircraft, aircraft exterior speaker systems, and methods of projecting sound waves from an exterior of an aircraft are provided. An aircraft includes an outer skin membrane, a vibration actuator, and a controller. The outer skin membrane has an exterior surface that defines an exterior boundary of the aircraft. The vibration actuator is coupled for common vibration with the outer skin membrane. The controller is operatively coupled with the vibration actuator and is configured to generate a command for the vibration actuator based on audible content to be projected from the exterior surface. The controller is further configured to transmit the command to the vibration actuator. The vibration actuator is configured to vibrate in response to receiving the command.

Aircraft, aircraft exterior speaker systems, and methods of projecting sound waves from an exterior of an aircraft are provided. An aircraft includes an outer skin membrane, a vibration actuator, and a controller. The outer skin membrane has an exterior surface that defines an exterior boundary of the aircraft. The vibration actuator is coupled for common vibration with the outer skin membrane. The controller is operatively coupled with the vibration actuator and is configured to generate a command for the vibration actuator based on audible content to be projected from the exterior surface. The controller is further configured to transmit the command to the vibration actuator. The vibration actuator is configured to vibrate in response to receiving the command.

An electroacoustic transducer comprising an electromechanical transducer and a vibratory component. The latter has a generally cylindrical side wall, an outwardly directed portion at the base of the side wall, and a generally planar vibratory top wall extending inwardly from the rim of the side wall further from its base to close the upper end of the cylindrical side wall. The said outwardly directed portion is mounted on the electromechanical transducer.

An electroacoustic transducer comprising an electromechanical transducer and a vibratory component. The latter has a generally cylindrical side wall, an outwardly directed portion at the base of the side wall, and a generally planar vibratory top wall extending inwardly from the rim of the side wall further from its base to close the upper end of the cylindrical side wall. The said outwardly directed portion is mounted on the electromechanical transducer.

Low frequency alarm tones emitted by life safety devices are more like to notify sleeping children and the elderly. Disclosed herein is a life safety device equipped with a novel, compact, quarter-wave, folded resonant cavity which significantly increases the low frequency (400-700 Hz square wave) acoustic efficiency of an audio output transducer when the folded resonant cavity is acoustically coupled to the transducer forming an audio output apparatus. The folded resonant cavity is comprised of undulating, annular, acoustic passages to significantly reduce the length of the resonant cavity, thereby permitting the audio output apparatus to fit within the housing of conventional size life safety devices such as, but not limited to, residential and commercial smoke alarms and carbon monoxide alarms. Battery powered embodiments of the audio output apparatus comprising a folded resonant cavity passed audibility tests for low frequency alarm tones in smoke alarms specified by UL217.

Low frequency alarm tones emitted by life safety devices are more like to notify sleeping children and the elderly. Disclosed herein is a life safety device equipped with a novel, compact, quarter-wave, folded resonant cavity which significantly increases the low frequency (400-700 Hz square wave) acoustic efficiency of an audio output transducer when the folded resonant cavity is acoustically coupled to the transducer forming an audio output apparatus. The folded resonant cavity is comprised of undulating, annular, acoustic passages to significantly reduce the length of the resonant cavity, thereby permitting the audio output apparatus to fit within the housing of conventional size life safety devices such as, but not limited to, residential and commercial smoke alarms and carbon monoxide alarms. Battery powered embodiments of the audio output apparatus comprising a folded resonant cavity passed audibility tests for low frequency alarm tones in smoke alarms specified by UL217.

A noisemaker system includes: a node of an infrastructure system; and a noisemaker including a vibrating plate, the vibrating plate including a top surface and a bottom surface, the bottom surface of the vibrating plate in contact with an exterior surface of the node, and an actuator configured to engage the top surface of the vibrating plate and generate an acoustic signal.