Topic
Diaphragm (acoustics)
About: Diaphragm (acoustics) is a research topic. Over the lifetime, 5545 publications have been published within this topic receiving 34997 citations.
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16 Jun 2017
TL;DR: BackDoor, a system that develops the technical building blocks for harnessing non-linearities in microphone hardware and achieves upwards of 4kbps for proximate data communication, as well as room-level privacy protection against electronic eavesdropping.
Abstract: Consider sounds, say at 40kHz, that are completely outside the human's audible range (20kHz), as well as a microphone's recordable range (24kHz). We show that these high frequency sounds can be designed to become recordable by unmodified microphones, while remaining inaudible to humans. The core idea lies in exploiting non-linearities in microphone hardware. Briefly, we design the sound and play it on a speaker such that, after passing through the microphone's non-linear diaphragm and power-amplifier, the signal creates a "shadow" in the audible frequency range. The shadow can be regulated to carry data bits, thereby enabling an acoustic (but inaudible) communication channel to today's microphones. Other applications include jamming spy microphones in the environment, live watermarking of music in a concert, and even acoustic denial-of-service (DoS) attacks. This paper presents BackDoor, a system that develops the technical building blocks for harnessing this opportunity. Reported results achieve upwards of 4kbps for proximate data communication, as well as room-level privacy protection against electronic eavesdropping.
181 citations
Patent•
TL;DR: An improved fully implantable hearing aid (10) in this paper includes at least two microphones (28) to provide improved noise cancellation, and, with an array (132) of microphones, improved directivity.
Abstract: An improved fully implantable hearing aid (10) in a first aspect includes at least two microphones (28) to provide improved noise cancellation, and, with an array (132) of microphones (28), improved directivity. In a second aspect, the hearing aid (10) includes an improved microactuator (32') in which deflections of a pair of piezoelectric plates (68) are coupled by liquid (52') to a flexible diaphragm (44') for stimulating fluid (20a) within an inner ear (17) of a subject (12). In a third aspect, the improved hearing aid (10) includes a directional booster (200) that the subject (12), having an implanted hearing aid (10), may wear on their head (122) for increasing directivity of perceived sound. A fourth aspect of the present invention is an improved implantable microactuator (32", 32'") that generates a mechanical displacement of a diaphragm (82) or a face (96) in response to an applied electrical signal. A liquid coupling between the piezoelectric transducer (54", 54'") and the diaphragm (82) or face (96) provides a mechanical impedance match for the transducer (54", 54'").
170 citations
TL;DR: A miniature diaphragm-based Fabry-Perot (F-P) interferometric fiber optic sensor fabricated by novel techniques for pressure or acoustic wave measurement that is only approximately 0.32 mm in diameter is presented.
Abstract: We present a miniature diaphragm-based Fabry-Perot (F-P) interferometric fiber optic sensor fabricated by novel techniques for pressure or acoustic wave measurement that is only approximately 032 mm in diameter By choosing different diaphragm thicknesses and effective diameters, we obtain a sensor measurement range from 5 to 10,000 psi (1 psi = 5172 Torr) and a frequency response up to 2 MHz In addition, the sensor's F-P cavity can be set from micrometers to millimeters with a precision of several nanometers With the all-silica structure, the sensor is reliable, biocompatible, and immune to electromagnetic interference and has high-temperature sensing capability
161 citations
Patent•
TL;DR: In this paper, the use of linear optical transducers in several configurations to detect the motion of one or more conventional microphone diaphragms in proportional response to incident acoustic signals is described.
Abstract: Microphone having linear optical transducers. The present invention includes the use of linear optical transducers in several configurations to detect the motion of one or more conventional microphone diaphragms in proportional response to incident acoustic signals. A light source, such as a laser or a light emitting diode directs light onto a reflecting microphone diaphragm responsive to sound waves, and the position of the reflected light is monitored using a position sensitive detector which effectively eliminates effects of light source intensity on the optical transducer-processed signal. Other embodiments make use of either a fixed knife edge or a knife edge which moves in response to the motion of the diaphragm to interrupt the light source in a proportional manner to the amplitude of motion of the diaphragm.
157 citations
TL;DR: In this paper, an acoustic-to-electrical transducer for sensing body sounds is described, which comprises a capacitive sensor, whereby a stethoscope diaphragm forms one plate of a capacitor, with the second plate of the capacitor being co-planar to the diaphrasm.
Abstract: An acoustic-to-electrical transducer for sensing body sounds is disclosed. The transducer comprises a capacitive sensor, whereby a stethoscope diaphragm forms one plate of a capacitor, with the second plate of the capacitor being co-planar to the diaphragm. The capacitance of the two plates varies with the distance between them, said distance being modified by motion of the diaphragm in response to sound pressure. The sensor, circuitry, manufacturing methods and improvements are disclosed.
138 citations