Noise masked thresholds for 800 cps tonal pulses 25 to 400 milliseconds long were measured in masking noise bands from 18 to 1100 cps wide. It was found that the threshold remains constant for equal values of band-width pulse length product. The threshold varies according to a formula proposed on the basis of limited data in an earlier report (T. H. Schafer and C. A. Shewmaker, U. S. Navy Electronics Laboratory Report 372, 1953): S/N = m/BT0.8, where S is the signal power, N is the noise power in the pass band of the filter, B is the band width, T is the pulse length, and m is a constant.
Cerebrospinal fluid (CSF) fistulae almost invariably lead to meningitis, even in the absence of other clinically obvious sequelae of the fistula such as a CSF fluid leak. The only effective means of reducing the risk of meningitis is surgical closure of the fistula. If surgery is to be recommended to patients with CSF fistulae even if they are currently asymptomatic, the morbidity of the procedure must be a principal determinant of the chosen technique. Recovery after the extracranial approach to a CSF fistula is much more rapid than after an intracranial procedure. The extracranial route is also free of the long-term risk of epilepsy which accompanies a craniotomy. The principal disadvantage of the lateral extracranial approach, failure of treatment, has been largely eliminated following studies into the obliteration of simple bony cavities using free adipose grafts. This paper describes our use of the extracranial approach to closure of CSF fistulae of the lateral skull base.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.