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A cohort of 39 patients with confirmed raised intracranial pressure was investigated. Of these patients, 24 (62%) complained of tinnitus and 11 (28%) suffered from paroxysmal rotary vertigo. Intracranial hypertension can occur without the usual headache and visual symptoms. In such cases, the patient may be referred to the otolaryngological clinic and the condition may be mistaken for Menière's disease or a labyrinthine disorder. The Tympanic Membrane Displacement (TMD) technique now provides a non-invasive method of monitoring the intracranial and perilymphatic pressures. This study provides recommendations for the use of TMD techniques in the otolaryngological clinic for screening, diagnosing and monitoring treatment of patients presenting with raised perilymphatic pressure.

Although it has been established that the middle ear muscles contract prior to vocalization, it is not known which muscle is mainly responsible for this activity. Also, there have been contradictory reports about whether this activity in stutterers differs from that of normal speakers. To tackle these questions, extratympanic pressure measurements prior to vocalization are reported for normal speakers and stutterers. This measure allows activity deriving from the two middle ear muscles to be differentiated and for the temporal course to be followed more accurately than by impedance measurement. To establish which muscle is primarily responsible for the pre-vocalization activity, the measured pressure changes prior to vocalization are compared with activity measured in tasks known to involve the stapedius or tensor tympani alone. These data show that in normal speakers and stutterers, the activity that is measured prior to vocalization resembles that of the tensor tympani. Contrary to other reports, there is no difference between normal speakers and stutterers in the time course of this activity.

A new technique based on constant pressure metrology has been developed to measure displacement of the tympanic membrane. Known as the Tympanic Membrane Displacement Measurement System (TMD system), this device is designed to be suitable for application in the audiology clinic. The TMD system resolves volume displacements as small as a nanolitre. Measurements are absolute--being independent of volume and compliance of the external auditory meatus, have a wide dynamic range, and are essentially made under free-field conditions. It employs closed volume metrology which allows the meatal pressure to be varied independently of the ambient pressure. The principle of constant pressure metrology using a standard TDH-39 headphone cone is discussed. Details are provided on the electronics, mechanical hardware, and software used for evaluating aural cardiovascular activity, stapedial muscle reflex, swallowing and Eustachian tube function.