Paracusis Willisii

Abstract
This paper describes the investigation of 29 ears in 16 patients with paracusis Willisii. 10 ears with normal hearing were used as control material. The investigation was based on pure tone and speech audiometry in high and low frequency background noise. Background noise causes no real improvement in the threshold of hearing in patients with paracusis Willisii. The masking effect is the same in patients with paracusis Willisii and in persons with normal hearing. Paracusis Willisii cannot therefore be the cause of any objective improvement in the signal-noise ratio. In high and low frequency noise the masking effect on discrimination is the same; low frequency noise is not therefore a condition for the experience of paracusis Willisii. Persons with normal hearing raise their voices in noise in order to be understood and to control their own speech, and this increased speech intensity is of benefit to the patient with paracusis Willisii who is hard of hearing. With increasing intensity of noise the threshold of hearing in patients with paracusis Willisii will approach that of those with normal hearing more and more. Patients with perceptive loss of hearing can also have paracusis Willisii. A condition for the experience of paracusis Willisii is that those who are hard of hearing can bear a high pressure of speech; this means that the cochlear function is good. Noise audiometry would seem to be a satisfactory method of investigating the cochlear function, and in operations for the improvement of hearing it can have prognostic value.

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