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OBJECTIVE To evaluate optimal placement of the Floating Mass Transducer of the Vibrant Soundbridge (Med-El, Innsbruck, Austria) against the round window membrane, particularly the impact of interposed coupling fascia and of covering materials. METHOD : Six fresh human cadaveric temporal bones were used. After mastoidectomy, posterior tympanotomy and(More)
A prototype of a novel bone-conduction hearing actuator based on a piezoelectric bending actuator is presented. The device lies flat against the skull which would allow it to form the basis of a subcutaneous bone-anchored hearing aid. The actuator excites bending in bone through a local bending moment rather than the application of a point force as with(More)
The fabrication and performance of a 256-element high-frequency (40-MHz) linear array is described. The array was fabricated using a high-frequency 1-3 PZT-polymer composite material developed in our laboratory. The spacing of the pillars in the composite was chosen to match the 40-microm center-to-center element spacing of the array electrodes. The element(More)
In this paper, radial modulation imaging of microbubbles is investigated at high frequency. A modulation pulse frequency of 3.7 MHz with an amplitude ranging from 0 to 250 kPa, and a 1.3-MPa 20-MHz broadband imaging pulse were used. Radial modulation effects were observed on a population of flowing microbubbles and quantified using a Doppler-type processing(More)
OBJECTIVE In our laboratory, a decrease in fetal lung maturity (FLM) testing on amniotic fluid occurred over a 10-year period, and we desired to determine if this was a national phenomenon and, if present, ascertain possible etiologies. STUDY DESIGN Society of Maternal-Fetal Medicine fellows, both in academic centers and private practice, were surveyed(More)
The results of a study of the three-dimensional vibration of two dry human skulls in response to harmonic excitation are presented. The vibratory response exhibits three distinct types of motion across the range of audible frequencies. At low frequencies below 1000 Hz, whole-head quasi-rigid motion is seen. At the middle frequencies between 1000 and 6000(More)
The effect of electromechanical cross talk in high-frequency (> 30 MHz) kerfless annular arrays is investigated. Finite-element model predictions of the radiation patterns from arrays are compared to predictions from an ideal model without cross talk and with experimental measurements. High cross talk in the array causes element broadening and an increase(More)
The design, fabrication, and performance of miniature high-frequency annular arrays are described. A 50-MHz, 2-mm-diameter, 7-element, equal-area annular array was fabricated and tested. The array elements were defined using photolithography and the electrical contacts were made using ultrasonic wire bonding. The resulting transducer produced pulses with a(More)
Digital transmit and receive beamformers for a 45-MHz, 7-element annular array are described. The transmit beamformer produces 0- to 80-Vpp monocycle pulses with a timing error of less than +/-125 ps. Up to four adjustable transmit focal zones can be selected. The dynamic receive beamformer uses a variable frequency sampling technique in which the frequency(More)
The bone-anchored-hearing-aid (BAHA) transduces airborne sound into skull vibration. Current bilateral BAHA configurations, for sounds directly facing listeners, will apply forces that are in-phase with each other and directed roughly towards the center of the head. Below approximately 1000 Hz the two cochleae respond in approximately the same direction and(More)