ABSTRACT
Wind noise was measured in four behind-the-ear hearing instruments with different microphone openings. A silent airflow of 7 m/s was directed toward the ear of a Kemar head and the resulting wind noise was measured. The amplification was set to an insertion gain of 35 dB at 1.6 kHz. The wind noise amplitude at the position of the drum ranged from 84 to 97 dB(A). The hearing instrument with a partially covered microphone entrance proved best, whereas one with an open microphone entrance had the poorest performance. A reduction in wind noise of 6-17 dB could be achieved in all hearing instruments by using a simple windscreen made of Styrofoam. The windscreen affected the frequency response by less than 2 dB. By subtracting the insertion gain from the wind noise, an equivalent wind noise could be presented as a function of frequency. A considerable difference was found between the wind noise sensitivity in different hearing instruments. All could be improved by a windscreen without adversely affecting the frequency response.
Subject(s)
Hearing Aids , Noise , Acoustic Stimulation/instrumentation , Auditory Perception/physiology , Correction of Hearing Impairment , Equipment Design , Humans , Noise/adverse effects , Patient Satisfaction , Pilot Projects , WindABSTRACT
Two patients with complex partial epilepsy and tumour of the temporal lobe scheduled for gamma knife radiosurgery were evaluated pre- and postoperatively by multichannel magnetoencephalography (MEG). Centers of epileptic dipole activity found preoperatively disappeared after the focal irradiation as did the epileptic seizures. Thus, to combine stereotactic MEG and gamma knife radiosurgery seems to be a non-invasive alternative to the conventional neurosurgery in focal epilepsy.
Subject(s)
Epilepsies, Partial/surgery , Magnetoencephalography , Radiosurgery/methods , Adult , Epilepsies, Partial/diagnosis , Epilepsies, Partial/physiopathology , Female , Humans , MaleABSTRACT
A device is presented that permits several applications for the Leksell stereotaxic system. The patient is fixed in this new system by means of a rectangular instrument that connects to the standard Leksell stereotaxic coordinate frame and maintains spatial orientation after the frame itself is removed. Specific uses for this device include stereotaxic radiosurgery and stereotaxic guidance during microsurgery. Other attractive features of this device are its capability of being precisely reapplied, its compatibility with both computerized tomography and magnetic resonance imaging, and the availability of an accessory device to adapt it for animal stereotaxis.
Subject(s)
Stereotaxic Techniques/instrumentation , Humans , Magnetic Resonance Spectroscopy , Tomography, X-Ray Computed/instrumentationABSTRACT
The necessity for intraoperative computer tomographic (CT) visualization of stereotactic probes and for the immediate assessment of the results of therapeutic intervention has brought about the integration of CT and stereotactic surgical sites. In order to perform intraoperative CT imaging, a simple mechanical device has been developed to hold a probe at the target. This device replaces the conventional semicircular arc that was used to guide the probe to the target during stereotactic procedures. Intraoperative imaging during a CT stereotactic procedure was accomplished without significant artifacts.
Subject(s)
Cerebral Ventricles/surgery , Cysts/surgery , Stereotaxic Techniques/instrumentation , Tomography, X-Ray Computed/instrumentation , Brain Diseases/diagnostic imaging , Brain Diseases/surgery , Cysts/diagnostic imaging , Female , Humans , Middle AgedABSTRACT
A method for stereotactic coordinate determination by means of X-ray tomography is presented. A standard stereotactic method has been slightly modified, and the localization procedure has been adapted to CT scanning as well as conventional tomography. The technique allows rapid and accurate determination of the instrument coordinates of the target by the surgeon and may be used in conjunction with any standard CT body scanner or X-ray tomograph.
