| hearing loss, central | Hearing loss due to central nervous system disease, anywhere in the auditory pathways from the cochlear nucleus of the pons to the auditory cortex. (12 Dec 1998) |
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| hearing loss, conductive | Hearing loss due to interference with the acoustic transmission of sound to the cochlea. The interference is in the outer or middle ear. (12 Dec 1998) |
| hearing loss, functional | Hearing loss without a physical basis. (12 Dec 1998) |
| hearing loss, high-frequency | Hearing loss in frequencies above 1000 hertz. (12 Dec 1998) |
| hearing loss, noise-induced | Hearing loss from exposure to noise. The loss is often in the frequency range 4000-6000 hertz. (12 Dec 1998) |
| hearing loss, partial | A condition in which the sense of hearing, although defective, is functional with or without a hearing aid. The hearing level for speech is approximately 40-70 decibels I.s.o. (international organization for standardization) or 30-60 db a.s.a. (american standards association). (12 Dec 1998) |
| hearing loss, sensorineural | Hearing loss resulting from damage to the sensory mechanism internal from the oval and round windows. (12 Dec 1998) |
| Helmholtz theory of hearing | That the basilar membrane of the cochlea acts as a resonating structure, recording low tones from its apical turns and high tones from its basal turns. Synonym: Helmholtz theory of hearing. (05 Mar 2000) |
| sensorineural hearing loss | <neurology> A form of deafness that occurs due to dysfunction of the auditory nerve (cranial nerve VIII). (27 Sep 1997) |
| normal hearing | The ability to perceive sound normally. Synonym: normal hearing. Origin: G. Akousis, hearing (05 Mar 2000) |
| organ of hearing | The content of the cochlea including the portion of the membranous labyrinth containing the spiral organ (cochlear duct) and the perilymphatic channels (scalae) which lie on either side. Synonym: labyrinthus cochlearis, organ of hearing. (05 Mar 2000) |
| analog-digital conversion | The process of converting analog data such as continually measured voltage to discrete, digital form. (12 Dec 1998) |
| angiography, digital subtraction | A method of delineating blood vessels by subtracting a tissue background image from an image of tissue plus intravascular contrast material that attenuates the X-ray photons. The background image is determined from a digitised image taken a few moments before injection of the contrast material. The resulting angiogram is a high-contrast image of the vessel. This subtraction technique allows extraction of a high-intensity signal from the superimposed background information. The image is thus the result of the differential absorption of X-rays by different tissues. (12 Dec 1998) |
| annular part of fibrous digital sheath | One of the two circular fibrous bands of the fibrous sheaths of the fingers and toes attached to the shaft of the proximal and middle phalanges. Synonym: pars annularis vaginae fibrosae, annular pulley, annulus of fibrous sheath, ligamentum annulare digitorum. (05 Mar 2000) |
| radiography, dental, digital | A rapid, low-dose, digital imaging system using a small intraoral sensor instead of radiographic film, an intensifying screen, and a charge-coupled device. It presents the possibility of reduced patient exposure and minimal distortion, although resolution and latitude are inferior to standard dental radiography. A receiver is placed in the mouth, routing signals to a computer which images the signals on a screen or in print. It includes digitizing from X-ray film or any other detector. (12 Dec 1998) |