Securing mechanisms for space access devices, such as an audio signal transmitting device, include a plurality of flattened members that are configured to transition from a relaxed state to a securing state when the space access device is inserted into an internal space or opening that has an inside diameter smaller than an outside diameter of the flattened members in the relaxed state. The flattened members securely engage a surface of the internal space and conform to the shape and size of the internal space. An amount of force applied by the flattened members to the surface of the internal space can be tuned by changing a stiffness of a rib supporting the flattened member.

A speaker system includes an enclosure, a speaker unit, and an elastic sheet. The speaker unit is disposed in the enclosure. The elastic sheet includes a first fiber made of a resin and a second fiber made of a resin, and is disposed in the enclosure. The second fiber is thicker than the first fiber and entangled with the first fiber.

A speaker system includes an enclosure, a speaker unit, and an elastic sheet. The speaker unit is disposed in the enclosure. The elastic sheet includes a first fiber made of a resin and a second fiber made of a resin, and is disposed in the enclosure. The second fiber is thicker than the first fiber and entangled with the first fiber.

An air-pulse generating device, a wearable sound device, a fanless blower, and an airflow producing method are disclosed. The air-pulse generating device includes a film structure, configured to be actuated to generate a plurality of air pulses at an ultrasonic pulse rate. The plurality of air pulses produces a net airflow toward one single direction.

An air-pulse generating device, a wearable sound device, a fanless blower, and an airflow producing method are disclosed. The air-pulse generating device includes a film structure, configured to be actuated to generate a plurality of air pulses at an ultrasonic pulse rate. The plurality of air pulses produces a net airflow toward one single direction.

Securing mechanisms for space access devices, such as an audio signal transmitting device, include a plurality of flattened members that are configured to transition from a relaxed state to a securing state when the space access device is inserted into an internal space or opening that has an inside diameter smaller than an outside diameter of the flattened members in the relaxed state. The flattened members securely engage a surface of the internal space and conform to the shape and size of the internal space. An amount of force applied by the flattened members to the surface of the internal space can be tuned by changing a stiffness of a rib supporting the flattened member.

Techniques are disclosed relating to sensors configured to measure acceleration and pressure. In various embodiments, an apparatus includes a first hydrophone sensor having a first piezoelectric material and a first housing structure and a second hydrophone sensor having a second piezoelectric material and a second housing structure. In some embodiments, the apparatus includes a first pair of wires configured to provide a first differential voltage and a second pair of wires configured to provide a second differential voltage. The first pair of wires may be coupled to the first hydrophone sensor and the second pair of wires may be coupled to the second hydrophone sensor. In various embodiments, the apparatus is configured to determine, based on the first and second differential voltages, a pressure and an acceleration experienced by the first and second hydrophone sensors.

Techniques are disclosed relating to sensors configured to measure acceleration and pressure. In various embodiments, an apparatus includes a first hydrophone sensor having a first piezoelectric material and a first housing structure and a second hydrophone sensor having a second piezoelectric material and a second housing structure. In some embodiments, the apparatus includes a first pair of wires configured to provide a first differential voltage and a second pair of wires configured to provide a second differential voltage. The first pair of wires may be coupled to the first hydrophone sensor and the second pair of wires may be coupled to the second hydrophone sensor. In various embodiments, the apparatus is configured to determine, based on the first and second differential voltages, a pressure and an acceleration experienced by the first and second hydrophone sensors.

Techniques are disclosed relating to calibrating sensors configured to measure both pressure and acceleration. In various embodiments, a system detects a first voltage produce by a first piezoelectric material in a hydrophone when the hydrophone is exposed to an acceleration and detects a second voltage produced by a second piezoelectric material in the hydrophone when the hydrophone is exposed to the acceleration. The system, in some embodiments, compares the first voltage and the second voltage. Based on the comparing of the first and second voltages, in some embodiments, the system determines a resistance for a variable resistor coupled to one of the first and second piezoelectric materials.

Securing mechanisms for space access devices, such as an audio signal transmitting device, include a plurality of outwardly projecting members that are configured to transition from a relaxed state to a securing state when the space access device is inserted into an internal space or opening that has an inside diameter smaller than an outside diameter of the outwardly projecting members in the relaxed state. The outwardly projecting members securely engage a surface of the internal space and conform to the shape and size of the internal space. A sound blocking portion can be provided to substantially prevent air/sound flow past the sound blocking portion of the securing mechanism.